BACKGROUND OF THE INVENTION

The present application is concerned with media streaming concepts which may be implemented, for instance, using DASH or some other adaptive streaming environment.

There are several delay-sensitive services that involve a low end-to-end latency, such as events live streaming or VR-streaming (VR=Virtual Reality). When such services are provided using adaptive HTTP streaming techniques, such as MPEG-DASH, some issues arise that make it more challenging to provide a service of quality. Typically, services based on HTTP adaptive streaming make use of a long buffer that helps overcome variations in the network characteristics (instantaneous throughput), as well as in the bitrate of the media stream. Typical buffer lengths used for VoD services (VoD=Video on Demand) might be from 20 seconds up to a couple of minutes.

However, for the mentioned delay-sensitive services, buffer lengths might be from a few hundreds of milliseconds up to a couple of seconds. Under some circumstances, such as small temporary throughput variations, client might need to switch to another representation with a different quality since the buffer might not be long enough to compensate for network variations. In addition to switching, fast tune-in times might be involved for some services. This is important for instance for live streaming services, where a client has to be very close the edge, i.e., to the real time.

In order to be able to perform fast tune-in or “any-time” switching, a Random Access Point (RAP) has to be had very frequently. One of the drawbacks of having very frequent RAPs within a stream is that the coding efficiency sharply decreases as the RAP frequency increases.

FIG. 17shows by way of a bar graph the BD-rate gains when coding four different videos at RAP periods of 32 frames (left-hand bars) and 64 frames (right-hand bars), respectively, compared to coding the same videos at RAP pitch/period of 16 frames, respectively. This means that simply reducing the RAP distance is no solution as it decreases RD performance.

SUMMARY

According to an embodiment, a device for streaming media content from a server may have: a deriver configured to derive media information from the server, and the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, for each of at least a subset of representations, a temporal distribution of random access points of the respective representation, and for each of at least a sub-subset of one or more representations of the subset of representations, a temporal alternation of first intervals of the media content coded into the respective representation and second intervals of the media content lying between the first intervals, a segment downloader configured to download the media content from the server in a sequence of segments with selecting on the basis of the first and second information, for each of at least a subset of the sequence of segments, one of the subset of representations and retrieving the respective segment from the representation selected for the respective segment.

Another embodiment may have a manifest file having a media presentation description having first information specifying a set of representations of media content at which the media content is available for download at a server; second information on, for each of at least a subset of one or more representations of the set of representations, a temporal distribution of random access points of the respective representation, and a temporal alternation of first intervals of the media content coded into the respective representation and second intervals of the media content lying between the first intervals.

Another embodiment may have a server offering a download of a media content, wherein the server stores and sends-out, upon request, to a client segments of a set of representations of the media content, with the representations of the set of representations having the media content coded thereinto in segments, the representations of at least a subset of the set of representations differing in a temporal distribution of random access points, and each of at least a sub-subset of one or more representations of the subset of representations having coded thereinto the media content intermittently; and a media presentation description having first information specifying the set of representations of media content at which the media content is available for download; second information on, for each of at least a subset of one or more representations of the subset of representations, a temporal distribution of random access points of the respective representation, and a temporal alternation of first intervals of the media content coded into the respective representation and second intervals of the media content lying between the first intervals.

According to another embodiment, a method for streaming media content from a server may have the following steps: deriving media information from the server, and the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, for each of at least a subset of representations, a temporal distribution of random access points of the respective representation, and for each of at least a sub-subset of one or more representations of the subset of representations, a temporal alternation of first intervals of the media content coded into the respective representation and second intervals of the media content lying between the first intervals, downloading the media content from the server in a sequence of segments with selecting on the basis of the first and second information, for each of at least a subset of the sequence of segments, one of the subset of representations and retrieving the respective segment from the representation selected for the respective segment.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for streaming media content from a server, the method having the steps of: deriving media information from the server, and the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, for each of at least a subset of representations, a temporal distribution of random access points of the respective representation, and for each of at least a sub-subset of one or more representations of the subset of representations, a temporal alternation of first intervals of the media content coded into the respective representation and second intervals of the media content lying between the first intervals, downloading the media content from the server in a sequence of segments with selecting on the basis of the first and second information, for each of at least a subset of the sequence of segments, one of the subset of representations and retrieving the respective segment from the representation selected for the respective segment, when said computer program is run by a computer.

According to another embodiment, a device for streaming media content from a server may have: a deriver configured to derive media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, for a first representation of a subset of representations of the set of representations, a temporal distribution of random access points of the first representation, and third information on, for each of one or more second representations of the subset of representations, a temporal distribution of random access points of the respective second representation and specifying that the respective second representation is of lower priority than the first representation, a segment downloader configured to download the media content from the server in a sequence of segments with selecting on the basis for the media information, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, wherein the segment downloader is configured to, responsive to commencing downloading the media content by selecting and retrieving from any of the subset of representations, based on the second and third information, detect a next-to-come random access point of the first representation and, select for segments preceding the next-to-come random access point of the first representation, one of the one or more second representations, and for segments including and succeeding the next-to-come random access point of the first representation, the first representation.

Another embodiment may have a manifest file having a media presentation description having first information specifying a set of representations of a media content at which the media content is available for download; second information on, for a first representation of a subset of representations of the set of representations, a temporal distribution of random access points of the first representation, and a third information on, for each of one or more second representations of the subset of representations, a temporal distribution of random access points of the respective second representation and specifying that the respective second representation is of lower priority than the first representation.

Another embodiment may have a server offering a download of a media content, wherein the server stores and sends-out, upon request, to a client segments of a set of representations of the media content, with the representations of the set of representations having the media content coded thereinto in segments, and the representations of at least a subset of the set of representations differing in a temporal distribution of random access points, and a media presentation description having first information specifying the set of representations of the media content at which the media content is available for download at the server; second information on, for a first representation of the subset of representations of the set of representations, a temporal distribution of random access points of the first representation, and third information on, for each of one or more second representations of the subset of representations, a temporal distribution of random access points of the respective second representation and specifying that the respective second representation is of lower priority than the first representation.

According to another embodiment, a method for streaming media content from a server may have the following steps: deriving media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, for a first representation of a subset of representations of the set of representations, a temporal distribution of random access points of the first representation, and third information on, for each of one or more second representations of the subset of representations, a temporal distribution of random access points of the respective second representation and specifying that the respective second representation is of lower priority than the first representation, downloading the media content from the server in a sequence of segments with selecting on the basis for the media information, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, wherein the method may have the steps of, responsive to commencing downloading the media content by selecting and retrieving from any of the subset of representations, based on the second and third information, detecting a next-to-come random access point of the first representation and, selecting for segments preceding the next-to-come random access point of the first representation, one of the one or more second representations, and for segments including and succeeding the next-to-come random access point of the first representation, the first representation.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for streaming media content from a server, the method having the steps of: deriving media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, for a first representation of a subset of representations of the set of representations, a temporal distribution of random access points of the first representation, and third information on, for each of one or more second representations of the subset of representations, a temporal distribution of random access points of the respective second representation and specifying that the respective second representation is of lower priority than the first representation, downloading the media content from the server in a sequence of segments with selecting on the basis for the media information, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, wherein the method may have the steps of, responsive to commencing downloading the media content by selecting and retrieving from any of the subset of representations, based on the second and third information, detecting a next-to-come random access point of the first representation and, selecting for segments preceding the next-to-come random access point of the first representation, one of the one or more second representations, and for segments including and succeeding the next-to-come random access point of the first representation, the first representation, when said computer program is run by a computer.

According to another embodiment, a device for streaming media content from a server in segments may have a deriver configured to derive media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server, and second information on the temporal distribution of random access points of the representations of at least a subset of representations of the set of representations, and a segment downloader configured to download the media content from the server in a sequence of segments by selecting for each segment one of the set of representations on the basis of the media information and retrieving each segment from the representation selected for the respective segment, wherein the segment downloader is configured to perform the selection for a subsequence of segments of the sequence of segments on the basis of the first and second information such that the representation selected for the segments of the subsequence alternates between the representations of the subset of representations at segments where random access points of the representations of the subset of representations to which the selection alternates, are absent.

Another embodiment may have a manifest file having a media presentation description having first information specifying a set of representations of a media content at which the media content is available for download, and second information on the temporal distribution of random access points of the representations of at least a subset of representations of the set of representations, and a hint related to a temporal distance between random access points within a subsequence of segments resulting from selecting and retrieving the subsequence of segments from the subset of representations in a manner alternating between the representations of the subset of representations at segments where random access points of the representations of the subset of representations to which the selection alternates, are absent.

Another embodiment may have a server offering a download of a media content, wherein the server stores and sends-out, upon request, to a client a segments of a set of representations of the media content, with the representations of the set of representations having the media content coded thereinto in the segments, and the representations of at least a subset of the set of representations differing in a temporal distribution of random access points, and a media presentation description having a first information specifying a set of representations of the media content at which the media content is available for download at the server, and a second information on the temporal distribution of random access points of the representations of a subset of representations of the set of representations, and a hint related to a temporal distance between random access points within a subsequence of segments resulting from downloading the subsequence of segments from the subset of representations in a manner alternating between the representations of the subset of representations at segments where random access points of the representations of the subset of representations between which the selection alternates, are absent.

According to another embodiment, a method for streaming media content from a server in segments may have the steps of: deriving media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server, and second information on the temporal distribution of random access points of the representations of at least a subset of representations of the set of representations, and downloading the media content from the server in a sequence of segments by selecting for each segment one of the set of representations on the basis of the media information and retrieving each segment from the representation selected for the respective segment, wherein the selection for a subsequence of segments of the sequence of segments on the basis of the first and second information is performed such that the representation selected for the segments of the subsequence alternates between the representations of the subset of representations at segments where random access points of the representations of the subset of representations to which the selection alternates, are absent.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for streaming media content from a server in segments, the method having the steps of: deriving media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server, and second information on the temporal distribution of random access points of the representations of at least a subset of representations of the set of representations, anddownloading the media content from the server in a sequence of segments by selecting for each segment one of the set of representations on the basis of the media information and retrieving each segment from the representation selected for the respective segment, wherein the selection for a subsequence of segments of the sequence of segments on the basis of the first and second information is performed such thatthe representation selected for the segments of the subsequence alternates between the representations of the subset of representations at segments where random access points of the representations of the subset of representations to which the selection alternates, are absent, when said computer program is run by a computer.

According to another embodiment, a device for streaming media content from a server may have: a deriver configured to derive media information from the server, and the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, subdividing the set of representations into subsets of one or more representations, by bitrate or quality so that the subsets are associated with different bitrates and/or different qualities, and the representations of one subset are associated with one bitrate and/or quality, at least a predetermined subset of the subsets including at least two representations; third information on, for each representation of the predetermined subset, a temporal distribution of random access points of the respective representation, and a segment downloader configured to download the media content from the server in a sequence of segments with selecting on the basis of the media information, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, wherein the segment downloader is configured to perform rate adaptation by switching between the subsets; and responsive to switching to the predetermined subset, detecting, based on the third information, one of the representations of the predetermined subset which has, among the random access points of all representations of the predetermined subset, the random access point which occurs soonest relative to the switching to the predetermined subset, and selecting the one representation for a first segment at switching to the predetermined subset.

Another embodiment may have a manifest file having a media presentation description having first information specifying a set of representations of the media content at which the media content is available for download at a server; second information on, subdividing the set of representations into subsets of one or more representations, by bitrate or quality so that the subsets are associated with different bitrates and/or different qualities, for switching between the subsets for rate adaptivity, and the representations of one subset are associated with one bitrate and/or quality, with at least a predetermined subset of the subsets including at least two representations for switching between them for enabling fast tune-in; third information on, for each representation of the predetermined subset, a temporal distribution of random access points of the respective representation.

Another embodiment may have a server offering a download of a media content, wherein the server stores and sends-out, upon request, to a client segments of a set of representations of the media content, with the representations of the set of representations having the media content coded thereinto in segments, the set of representations being subdivided into subsets of one or more representations so that the subsets are associated with different bitrates and/or different qualities for allowing switching between the subsets for rate adaptivity, and the representations of one subset are associated with one bitrate and/or quality, the representations of at least a predetermined one of the subsets differing in a temporal distribution of random access points, and a media presentation description having first information specifying a set of representations of the media content at which the media content is available for download at a server; second information on, subdividing the set of representations into subsets of one or more representations, by bitrate or quality so that the subsets are associated with different bitrates and/or different qualities, for switching between the subsets for rate adaptivity, and the representations of one subset are associated with one bitrate and/or quality, with at least a predetermined subset of the subsets including at least two representations for switching between them for enabling fast tune-in; third information on, for each representation of the predetermined subset, a temporal distribution of random access points of the respective representation.

According to another embodiment, a method for streaming media content from a server may have the following steps: deriving media information from the server, and the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, subdividing the set of representations into subsets of one or more representations, by bitrate or quality so that the subsets are associated with different bitrates and/or different qualities, and the representations of one subset are associated with one bitrate and/or quality, at least a predetermined subset of the subsets including at least two representations; third information on, for each representation of the predetermined subset, a temporal distribution of random access points of the respective representation, and downloading the media content from the server in a sequence of segments with selecting on the basis of the media information, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, wherein the downloading includes performing rate adaptation by switching between the subsets; and responsive to switching to the predetermined subset, detecting, based on the third information, one of the representations of the predetermined subset which has, among the random access points of all representations of the predetermined subset, the random access point which occurs soonest relative to the switching to the predetermined subset, and selecting the one representation for a first segment at switching to the predetermined subset.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for streaming media content from a server, the method having the steps of: deriving media information from the server, and the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on, subdividing the set of representations into subsets of one or more representations, by bitrate or quality so that the subsets are associated with different bitrates and/or different qualities, and the representations of one subset are associated with one bitrate and/or quality, at least a predetermined subset of the subsets including at least two representations; third information on, for each representation of the predetermined subset, a temporal distribution of random access points of the respective representation, and downloading the media content from the server in a sequence of segments with selecting on the basis of the media information, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, wherein the downloading includes performing rate adaptation by switching between the subsets; and responsive to switching to the predetermined subset, detecting, based on the third information, one of the representations of the predetermined subset which has, among the random access points of all representations of the predetermined subset, the random access point which occurs soonest relative to the switching to the predetermined subset, and selecting the one representation for a first segment at switching to the predetermined subset, when said computer program is run by a computer.

According to another embodiment, a device for streaming media content from a server may have: a deriver configured to derive media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on a media content availability duration for which the media content is available at the server, and third information on a fast random access capability duration, a segment downloader configured to download the media content from the server in a sequence of segments with selecting, on the basis of the MPD, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, wherein the segment downloader is configured to, when commencing downloading the media content by selecting and retrieving from the subset of representations, derive a minimum of an availability duration of a primary representation of the subset of representations from the media content availability duration, and check whether the fast random access capability duration has already been exceeded, and if so, perform the selecting, on the basis of the MPD, for each of the sequence of segments, one of the set of representations in a manner so that a set of one or more secondary representations of the subset of representations are excluded from being selected, or the selection follows a predetermined one-dimensional temporal selection path through the representations of the subset, and if not, perform the selecting, on the basis of the MPD, for each of the sequence of segments, so that the set of one or more secondary representations of the subset of representations are available for selection and use the set of one or more secondary representations for a faster random access.

Another embodiment may have a server offering a download of a media content, wherein the server stores and sends-out, upon request, to a client segments of a set of representations of the media content, with the representations of the set of representations having the media content coded thereinto in segments, and the representations of at least a subset of the set of representations differing in a temporal distribution of random access points, and a media presentation description having a first information specifying a set of representations of a media content at which the media content is available for download at the server; a second information on a media content availability duration for which the media content is available at the server, and a third information on a fast random access capability duration, wherein the server is configured to provide a minimum availability duration for a primary representation of the set of representations according to the media content availability duration, and provide a minimum availability duration for a set of one or more secondary representations of the subset of representations according to the fast random access capability duration, wherein the fast random access capability duration is shorter than the media content availability duration.

According to another embodiment, a method for streaming media content from a server may have the following steps: deriving media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on a media content availability duration for which the media content is available at the server, and third information on a fast random access capability duration, downloading the media content from the server in a sequence of segments with selecting, on the basis of the MPD, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, the method having the steps of, when commencing downloading the media content by selecting and retrieving from the subset of representations, deriving a minimum of an availability duration of a primary representation of the subset of representations from the media content availability duration, and checking whether the fast random access capability duration has already been exceeded, and if so, perform the selecting, on the basis of the MPD, for each of the sequence of segments, one of the set of representations in a manner so that a set of one or more secondary representations of the subset of representations are excluded from being selected, or the selection follows a predetermined one-dimensional temporal selection path through the representations of the subset, and and if not, perform the selecting, on the basis of the MPD, for each of the sequence of segments, so that the set of one or more secondary representations of the subset of representations are available for selection und use the set of one or more secondary representations for a faster random access.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for streaming media content from a server, the method having the steps of: deriving media information from the server, the media information having first information specifying a set of representations of the media content at which the media content is available for download at the server; second information on a media content availability duration for which the media content is available at the server, and third information on a fast random access capability duration, downloading the media content from the server in a sequence of segments with selecting, on the basis of the MPD, for each of the sequence of segments, one of the set of representations and retrieving the respective segment from the representation selected for the respective segment, the method having the steps of, when commencing downloading the media content by selecting and retrieving from the subset of representations, deriving a minimum of an availability duration of a primary representation of the subset of representations from the media content availability duration, and checking whether the fast random access capability duration has already been exceeded, and if so, perform the selecting, on the basis of the MPD, for each of the sequence of segments, one of the set of representations in a manner so that a set of one or more secondary representations of the subset of representations are excluded from being selected, or the selection follows a predetermined one-dimensional temporal selection path through the representations of the subset, and if not, perform the selecting, on the basis of the MPD, for each of the sequence of segments, so that the set of one or more secondary representations of the subset of representations are available for selection und use the set of one or more secondary representations for a faster random access, when said computer program is run by a computer.

According to another embodiment, a media content source provider for generating a set of representations of a media content for live-streaming may have a media content input for the media content, one or more encoders for encoding the media content into a set of representations in segments so that the representations of the set of representations differ in a temporal distribution of random access points, an output for outputting the set of representations, wherein the media content source provider is configured so that the set of the representations has at least one first representation into which the media content is coded continuously, and at least one second representation into which the media content is coded intermittently so that, within each interval between consecutive random access points of the first representation, the at least one second representation has at least one first segment within which the media content is not coded into the at least one second representation or within which the media content is coded into the at least one second representation at reduced quality, and at least one second segment forming a random access point of the at least one second representation.

According to another embodiment, a method for generating a set of representations of a media content for live-streaming may have the steps of: receiving the media content, encoding the media content into a set of representations in segments so that the representations of the set of representations differ in a temporal distribution of random access points, wherein the media content source provider is configured so that the set of the representations has at least one first representation into which the media content is coded continuously, and at least one second representation into which the media content is coded intermittently so that, within each interval between consecutive random access points of the first representation, the at least one second representation has at least one first segment within which the media content is not coded into the at least one second representation or within which the media content is coded into the at least one second representation at reduced quality, and at least one second segment forming a random access point of the at least one second representation.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for generating a set of representations of a media content for live-streaming, the method having the steps of: receiving the media content, encoding the media content into a set of representations in segments so that the representations of the set of representations differ in a temporal distribution of random access points, wherein the media content source provider is configured so that the set of the representations has at least one first representation into which the media content is coded continuously, and at least one second representation into which the media content is coded intermittently so that, within each interval between consecutive random access points of the first representation, the at least one second representation has at least one first segment within which the media content is not coded into the at least one second representation or within which the media content is coded into the at least one second representation at reduced quality, and at least one second segment forming a random access point of the at least one second representation, when said computer program is run by a computer.

According to another embodiment, a media content source provider for generating a set of representations of a media content for live-streaming may have: a media content input for the media content, one or more encoders for encoding the media content into a set of representations in segments so that the representations of the set of representations differ in a temporal distribution of random access points, an output for outputting the set of representations, wherein the media content source provider has a drift measurer configured to generate a drift measure for a drift of a sequence of segments of the media content resulting from selecting the segments from the set of representations with alternating between the representations at segments where the representations between which the selection alternates, have no random access point, and control at least one of the one or more encoders so that the coding of the media content into at least one of the set of representations depends on the drift measure.

According to another embodiment, a method for generating a set of representations of a media content for live-streaming may have the steps of: receiving a media content, by one or more encoders, encoding the media content into a set of representations in segments so that the representations of the set of representations differ in a temporal distribution of random access points, outputting the set of representations, generating a drift measure for a drift of a sequence of segments of the media content resulting from selecting the segments from the set of representations with alternating between the representations at segments where the representations between which the selection alternates, have no random access point, and controlling at least one of the one or more encoders so that the coding of the media content into at least one of the set of representations depends on the drift measure.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for generating a set of representations of a media content for live-streaming, the method having the steps of: receiving a media content, by one or more encoders, encoding the media content into a set of representations in segments so that the representations of the set of representations differ in a temporal distribution of random access points, outputting the set of representations, generating a drift measure for a drift of a sequence of segments of the media content resulting from selecting the segments from the set of representations with alternating between the representations at segments where the representations between which the selection alternates, have no random access point, and controlling at least one of the one or more encoders so that the coding of the media content into at least one of the set of representations depends on the drift measure, when said computer program is run by a computer.

The aspects of the present application discussed below are inspired by the idea that an efficient tune-in or anytime-switching into a certain media content is possible by rendering available the media content in more than one representation substantially relating to the same bitrate level and/or quality, so that the juxtaposition of the more than one representation may allow for a higher temporal RAP density than the individual representations, and/or vice versa, the juxtaposition of the more than one representation may allow for an increase of the temporal RAP density of the downloaded stream compared to the individual representations.

In accordance with a first aspect of the present application, media streaming is made more efficient in handling fast tune-in and any-time switching capabilities, by designing the set of representations of the media content in such a manner, and providing the client with information allowing same to derive, that the set of representations comprises at least a subset of representations of which each has a respective temporal distribution of random access points associated therewith, and of which at least a sub-subset of one or more representations has the media content coded thereinto intermittently, so that intervals of the media content coded into the respective representation are temporarily separated by other intervals of the media content lying between the coded intervals. By this measure, the aforementioned server-side overhead with respect to storage capacity and management is reduced, owing to the intermittent coding nature of the sub-subset of representations, and the subset of representations may be designed such that fast tune-in is feasible at dense grid of a pool of random access points stemming from all representations of the subset of representations. In accordance with an embodiment, 1) at least one representation of the subset has encoded thereinto the media content non-intermittently, 2) the one or more other (discontinuous) representations of the sub-subset has its RAPs temporarily distributed in such a manner that the frequency at which an RAP occurs in any of the subset or representations complies with the desired tune-in or any-time switching capability, and 3) it is true for each random access point of a discontinuous representation that either the media content is coded into this representation until the next-to-come random access point of the at least one continuous representation or it is possible to, at, or prior to, reaching a non-coded interval of the respective discontinuous representation to switch to another discontinuous representation via a random access point of the latter, thereby reaching the next-to-come random access point of the continuous representation. That is, by informing the streaming device on the temporal distribution of random access points of the subset of representations and the temporal alternation of coded first intervals and second intervals lying therebetween, with respect to the one or more discontinuous representations, the segment downloader of such a streaming device is able to take this information into account when downloading the media content. In particular, faster switching into the subset of representations is feasible. The set of representations at which the media content is rendered available for download at the server, may comprise, or may not comprise, additional representations beyond the subset of representations into which tune-in or any-time switching is rendered faster.

In accordance with the second aspect of the present application, the aim of more efficiently allowing for a fast tune-in or any-time switching capability, is achieved by designing at least a subset of the set of representations at which a media content is rendered available for download at the server, in such a manner that the temporal distribution of random access points is signaled for a subset of representations, and that 2) one or more second representations of this subset are signaled to be of lower priority than a first representation of the subset. By this measure, the streaming device or client knows about the subsidiary nature of the second representations relative to the first representation and that these second or subsidiary representations should merely be used for fast tune-in or any-time switching instances. The subsidiary or second representations do not necessarily need to be discontinuous representations, i.e., representations having the media content coded thereinto intermittently as is the case in accordance with the first aspect. Rather, the second or secondary representations could have the media content coded thereinto at varying quality, such as at reduced quality at intervals where switching to the first representation or to another second representation enables bridging of the time until the next-to-come random access point of the next representation. Alternatively, simple black or idle data intervals may be provided between coded intervals of the second representations instead of the aforementioned non-coded intervals of the first aspect so that the second representations in accordance with the second aspect would not result in an error at the client side if continuously reproduced, nevertheless reducing the storage capacity at the server-side. The second or subsidiary representations could even be designed in a “complete manner”, or in a manner like the first representation, i.e. could be completely coded. The priority ranking would in this case avoid that the streaming device remains being stuck in one of the secondary representations which may be less RD efficient than the first representation and should merely be used till reaching the next RAP of the first representation. The streaming device or client, being informed on the temporal distribution of random access points of the subset of representations is able to use the secondary representations in order to switch into any of the subset of representations earlier, than solely relying on the random access points of the first representation.

In accordance with a third aspect of the present application, streaming media content is made more efficient with respect to supporting fast tune-in and any-time switching, by offering to the streaming device or client within the set of representations at which the media content is available for download at the server, at least a subset of representations between which the streaming device may alternate at segments where random access points of the representations between which the alternation takes place, are absent. The subset of representations may comprise merely two representations. By alternating between these representations, the random access points of these representations may be “bypass” for a certain number of segments long to take advantage of a corresponding lower bitrate at which the media content is streamed. The server may inform the client about a relationship between quality and random access point distance resulting from bypassing a number of random access points of the subset of representations. For example, a promise may be provided to the streaming device or client informing the latter on a guaranteed quality met, adhering to some maximum random access point distance/pitch and the downloaded sequence selected from the subset of representations. As for the other aspects, the set of representations may, in addition to the subset of representations, comprise further representations or not.

In accordance with a fourth aspect of the present application, media streaming is made more efficient in handling fast tune-in and any-time switching capabilities, by designing the set of representations of the media content in such a manner that the set of representations is subdivided into subsets of one or more representations so that the subsets are associated with different bitrates and/or different qualities and allow for switching between the subsets for rate adaption, while the representations of one subset are associated with one bitrate and/or quality, and that the representations of at least a predetermined one of the subsets differ in a temporal distribution of random access points so as to enable fast tune-in, or switching to, the predetermined subset. Thus, in accordance with the fourth aspect of the present application, the subset subdivision represents a kind of clustering or, in different terms, provides a new dimension of offering the media content: a subset like the predetermined subset, enable faster tune-in or switching to the respective subset, but merely represent one adaption level for enabling rate adaptive download of the media content. In case of merely having one such subset, same allows for rapidly accessing the media content via this subset before starting rate adaptation by switching to other subsets which may have merely one representation each. In case of each subset allowing fast tune-in, same allows for rapidly switching between the bitrate and/or quality levels associated with the subsets so that rate adaptation is enabled at a fine temporal grid, thereby enabling a fast reactivity to transmission bandwidth variations and, accordingly, keeping buffer level for compensating bandwidth variation low. The at least one predetermined subset may, for example, be designed in accordance with the first, second or third aspect.

A fifth aspect of the present application seeks to render media streaming more efficient in terms of supporting fast tune-in or any-time switching by offering a set of representations at which a certain media content is available for download at the server, along with information on a media content availability duration and a fast random access capability duration. The former concerns a minimum of an availability duration of a primary representation of the subset of representations or of a predetermined one-dimensional selection path through the subset of representations, while the latter concerns the availability of secondary representations. If the secondary representations are still present according to the fast random access capability duration, the same may be used for fast tune-in or any-time switching, i.e., for a faster random access. By this measure, a live media stream may, for instance, be offered in a manner so that the effort in terms of storage capacity and management overhead at the server-side may be kept at a minimum around the “real time” of the media content.

The present application also provides concepts for generating sets of representations which may be used in connection with the first to fourth aspects of the present application. Thus, in accordance with a sixth aspect of the present application, a media content source provider which generates a set of representations of a media content for live streaming in such a manner that the set of representations comprises at least one continuous representation and at least one discontinuous representation. And with respect to a sixth aspect of the present application, a media content source provider generates a set of representations of a media content for live streaming in such a manner that a drift measurer controls one or more encoders used for encoding the media content into the set of representations depending on a drift measure which measures a sequence of segments of the media content resulting from selecting the segments from the set of representations, alternating between the representations and segments where the representations between which the selection alternates, have no random access point.

