user12669: This question is related to What is the correct MPEG-2 FourCC? and to an open discussion currently on the ffmpeg-user mailing list:

I am wondering if I should file a bug report about the MOV output. Open
questions in that vein, though, are:
...

Is it a bug that mpg2 and mpgv cause MOV output to fail or is that
correct behavior?


There seem to be numerous possible tags in use for MPEG-2 video, in particular m2v1, mp2v, mpg2, and mpgv.
Now, ffmpeg fails with e.g. "Tag mpgv/0x7667706d incompatible with
output codec id '2' (m2v1)" when the output is MOV and either mpg2 or mpgv is specified:
ffmpeg ... -vcodec mpeg2video -f mov ...             # succeeds (m1v1)
ffmpeg ... -vcodec mpeg2video -vtag mp2v -f mov ...  # succeeds
ffmpeg ... -vcodec mpeg2video -vtag mpg2 -f mov ...  # fails
ffmpeg ... -vcodec mpeg2video -vtag mpgv -f mov ...  # fails

All of those succeed for AVI. Ffmpeg's default tag for MPEG-2 in AVIs is mpg2.
Part of a bug report that I am writing for ffmpeg's MOV output handling may include the mpg2 and mpgv failure behavior (with the desired behavior being success), but before I do that I need to be certain that this behavior is a bug rather than appropriate behavior.
So my question boils down to this: Are mpg2 and mpgv valid, allowable alternative tags for MPEG-2 video in an MOV file, and are there others? I am looking for official Apple sources and MOV specifications rather than anecdotal evidence or lists of generally observed FourCC's / codec IDs.
I know that, at least according to Wikipedia, MPEG-2 video in an MOV is an acceptable combination, I'm just not sure what the acceptable set of codec tags are in MOVs. This question is not about the "correct" MPEG-2 ID in general cases, it is about the allowable variants specifically in MOVs.

user1871: MPEG-2 doesn't seem to be an officially sanctioned codec for the Quicktime container. The official specification has a section related to MPEG-1 in MOV but not MPEG-2. The US Library of Congress also does not have an entry for the subtype MPEG-2 in MOV, like it does for MPEG-1 (just called QTV_MPEG).
So, there's no official word on "allowable alternative tags". One can only examine MPEG-2 MOVs and see whether apps, specifically, Apple apps, play them or not and prepare a survey report. Since each app has its own fiat on whether it plays a file with a certain codec ID or not, that report whould be categorized by app i.e. VLC, Quicktime player. FCP..etc.
As an example, VLC recognizes the following tags for generic MPEG-2 i.e. not IMX or XDCAM:
    A("mpeg"),
    A("mp2v"),
    A("MPEG"),
    A("mpg2"),
    A("MPG2"),
    A("H262"),


12669: <p>This question is related to <a href="https://video.stackexchange.com/questions/17526/what-is-the-correct-mpeg-2-fourcc">What is the correct MPEG-2 FourCC?</a> and to an open discussion <a href="https://ffmpeg-user.ffmpeg.narkive.com/5qKNOLOF/mpeg-2-video-m2v1-vs-mp2v#post9" rel="nofollow noreferrer">currently on the ffmpeg-user mailing list</a>:</p>
<blockquote>
<p>I am wondering if I should file a bug report about the MOV output. Open
questions in that vein, though, are:</p>
<p>...</p>
<ul>
<li>Is it a bug that mpg2 and mpgv cause MOV output to fail or is that
correct behavior?</li>
</ul>
</blockquote>
<p>There seem to be numerous possible tags in use for MPEG-2 video, in particular <code>m2v1</code>, <code>mp2v</code>, <code>mpg2</code>, and <code>mpgv</code>.</p>
<p>Now, ffmpeg fails with e.g. &quot;Tag mpgv/0x7667706d incompatible with
output codec id '2' (m2v1)&quot; when the output is MOV and either <code>mpg2</code> or <code>mpgv</code> is specified:</p>
<pre><code>ffmpeg ... -vcodec mpeg2video -f mov ...             # succeeds (m1v1)
ffmpeg ... -vcodec mpeg2video -vtag mp2v -f mov ...  # succeeds
ffmpeg ... -vcodec mpeg2video -vtag mpg2 -f mov ...  # fails
ffmpeg ... -vcodec mpeg2video -vtag mpgv -f mov ...  # fails
</code></pre>
<p>All of those succeed for AVI. Ffmpeg's default tag for MPEG-2 in AVIs is <code>mpg2</code>.</p>
<p>Part of a bug report that I am writing for ffmpeg's MOV output handling may include the <code>mpg2</code> and <code>mpgv</code> failure behavior (with the desired behavior being success), but before I do that I need to be certain that this behavior is a bug rather than appropriate behavior.</p>
<p>So my question boils down to this: Are <code>mpg2</code> and <code>mpgv</code> valid, allowable alternative tags for MPEG-2 video <strong>in an MOV file</strong>, and are there others? I am looking for official Apple sources and MOV specifications rather than anecdotal evidence or lists of generally observed FourCC's / codec IDs.</p>
<p>I know that, at least <a href="https://en.wikipedia.org/wiki/Comparison_of_video_container_formats" rel="nofollow noreferrer">according to Wikipedia</a>, MPEG-2 video in an MOV is an acceptable combination, I'm just not sure what the acceptable set of codec tags are in MOVs. This question is not about the &quot;correct&quot; MPEG-2 ID in general cases, it is about the allowable variants specifically in MOVs.</p>
 1871: <p>MPEG-2 doesn't seem to be an officially sanctioned codec for the Quicktime container. The official specification has a section related to <a href="https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFChap3/qtff3.html#//apple_ref/doc/uid/TP40000939-CH205-BBCGIJJI">MPEG-1</a> in MOV but not MPEG-2. The US Library of Congress also does not have an entry for the <a href="http://www.digitalpreservation.gov/formats/fdd/fdd000052.shtml">subtype</a> MPEG-2 in MOV, like it does for MPEG-1 (just called QTV_MPEG).</p>

<p>So, there's no official word on "allowable alternative tags". One can only examine MPEG-2 MOVs and see whether apps, specifically, Apple apps, play them or not and prepare a survey report. Since each app has its own fiat on whether it plays a file with a certain codec ID or not, that report whould be categorized by app i.e. VLC, Quicktime player. FCP..etc.</p>

<p>As an example, VLC recognizes the <a href="https://github.com/videolan/vlc/blob/9053b0919f00d88f16e1ef3e3f79b1cced74f742/src/misc/fourcc_list.h">following tags</a> for generic MPEG-2 i.e. not IMX or XDCAM:</p>

<pre><code>    A("mpeg"),
    A("mp2v"),
    A("MPEG"),
    A("mpg2"),
    A("MPG2"),
    A("H262"),
</code></pre>
