When trying to DASH 6.1 channel E-AC-3 with mp4box, it gives this error `Unknown CICP mapping for channel config 4/2.1` and outputs a null channel configuration in the manifest: `<AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="0"/>`

I have not tried it with 6.1 AAC, but I've generally had bad luck with most web browsers and **any** AAC channel configuration that isn't 5.1, stereo, or mono.

I _believe_ it should be writing either or both of those channel configurations:
```
    <AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="11"/>
    <AudioChannelConfiguration schemeIdUri="tag:dolby.com,2014:dash:audio_channel_configuration:2011" value="F901"/>
```

The first value is from [page 237 of ETSI TS 106 366](https://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.04.01_60/ts_102366v010401p.pdf).

The second was derived using:
```
**Dolby XXXX hex bitmask**
MSB->LSB 16bit
Left/Center/Right/LeftSurround/RightSurround/LeftCent_RightCentpair/LeftRearSur_RightRearSurpair/CenterSur/TopCenterSur/Lsurdirect_Rsdpair/Lwide_Rwpair/LVertHeight_Rvhpair/CentVertHeight/Lts_Rtspair/LFE2/LFE
e.g. 5.1 = 1111100000000001 = F801
```

I flipped an extra bit to indicate the presence of `CenterSur`, giving me `1111100100000001` or F901.

If you need a short sample, I have attached one. https://github.com/gpac/gpac/assets/81622808/d85e240d-a06f-49cb-9809-ebf805406af8

- [ ✅ ] I looked for a similar issue and couldn't find any.
- [ ✅ ] I tried with the latest version of GPAC. Installers available at https://gpac.io/downloads/gpac-nightly-builds/
- [ ✅ ] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: https://gpac.io/bug-reporting/

6.1ch audio gives a channel map error with DASH
This is a GitHub Issue
repo:gpac
owner:gpac
Title : 6.1ch audio gives a channel map error with DASH
Issue date:

--- start body ---
When trying to DASH 6.1 channel E-AC-3 with mp4box, it gives this error `Unknown CICP mapping for channel config 4/2.1` and outputs a null channel configuration in the manifest: `<AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="0"/>`

I have not tried it with 6.1 AAC, but I've generally had bad luck with most web browsers and **any** AAC channel configuration that isn't 5.1, stereo, or mono.

I _believe_ it should be writing either or both of those channel configurations:
```
    <AudioChannelConfiguration schemeIdUri="urn:mpeg:mpegB:cicp:ChannelConfiguration" value="11"/>
    <AudioChannelConfiguration schemeIdUri="tag:dolby.com,2014:dash:audio_channel_configuration:2011" value="F901"/>
```

The first value is from [page 237 of ETSI TS 106 366](https://www.etsi.org/deliver/etsi_ts/102300_102399/102366/01.04.01_60/ts_102366v010401p.pdf).

The second was derived using:
```
**Dolby XXXX hex bitmask**
MSB->LSB 16bit
Left/Center/Right/LeftSurround/RightSurround/LeftCent_RightCentpair/LeftRearSur_RightRearSurpair/CenterSur/TopCenterSur/Lsurdirect_Rsdpair/Lwide_Rwpair/LVertHeight_Rvhpair/CentVertHeight/Lts_Rtspair/LFE2/LFE
e.g. 5.1 = 1111100000000001 = F801
```

I flipped an extra bit to indicate the presence of `CenterSur`, giving me `1111100100000001` or F901.

If you need a short sample, I have attached one. https://github.com/gpac/gpac/assets/81622808/d85e240d-a06f-49cb-9809-ebf805406af8

- [ ✅ ] I looked for a similar issue and couldn't find any.
- [ ✅ ] I tried with the latest version of GPAC. Installers available at https://gpac.io/downloads/gpac-nightly-builds/
- [ ✅ ] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: https://gpac.io/bug-reporting/

--- end body ---

The issue describes a problem with the GPAC library when handling 6.1 channel E-AC-3 audio in DASH format, resulting in an error related to an unknown channel configuration mapping. This does not indicate a security vulnerability but rather a functionality issue with audio channel mapping in the library.