Answers.Body: <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>
  
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-28T22:03:17.767Z
Answers.Text: Thanks. I knew it wouldn't be easy. In the document you linked to [it says](http://apple.co/1PDDX8w) *"Table 4-1 shows some of the formats supported. The list is not exhaustive, and is subject to addition."* So while it doesn't define MPEG-2, it doesn't make it simple by explicitly disallowing it either. Further, I'm sure Apple software actually has been using it for some time. I know FCP X's "Compressor" does, and the ffmpeg source has a comment hinting that FCP 5 did. Still, the important thing is, `mp2v` and `mpgv` don't seem to be explicitly disallowed. I'll go with that.
Answers.UserDisplayName: Jason C
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-29T04:51:47.217Z
Answers.Text: "*list is not exhaustive*" -> true, but MPEG-2 was the dominant ISO format at the time of the original spec. That disclaimer probably covers niche codecs such as camcorders using some custom variant of MJPEG.
Answers.UserDisplayName: Gyan
Answers.ContentLicense: CC BY-SA 3.0
Answers.CreationDate: 2016-01-28T18:25:50.280Z
Answers.LastActivityDate: 2016-01-28T19:46:12.090Z
Answers.LastEditDate: 2016-01-28T19:46:12.090Z
Answers.UserDisplayName: Gyan
Body: <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>
  
Tags: <ffmpeg><quicktime><mpeg>
Title: Are "mp2v" and "mpgv" valid MPEG-2 codec tags in an MOV?
UserDisplayName: Jason C
ThreadText: # Are "mp2v" and "mpgv" valid MPEG-2 codec tags in an MOV?
  
  (Asked by: username_0 on 2016-01-28)
  
  This question is related to [What is the correct MPEG-2 FourCC?](https://video.stackexchange.com/questions/17526/what-is-the-correct-mpeg-2-fourcc) and to an open discussion [currently on the ffmpeg-user mailing list](https://ffmpeg-user.ffmpeg.narkive.com/5qKNOLOF/mpeg-2-video-m2v1-vs-mp2v#post9):
  
  > 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](https://en.wikipedia.org/wiki/Comparison_of_video_container_formats), 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.
  
  **Tags:** ffmpeg, quicktime, mpeg
  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2016-01-28. Score: 3 | Accepted answer
  
  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](https://developer.apple.com/library/mac/documentation/QuickTime/QTFF/QTFFChap3/qtff3.html#//apple_ref/doc/uid/TP40000939-CH205-BBCGIJJI) in MOV but not MPEG-2. The US Library of Congress also does not have an entry for the [subtype](http://www.digitalpreservation.gov/formats/fdd/fdd000052.shtml) 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](https://github.com/videolan/vlc/blob/9053b0919f00d88f16e1ef3e3f79b1cced74f742/src/misc/fourcc_list.h) for generic MPEG-2 i.e. not IMX or XDCAM:
  
  ```
      A("mpeg"),
      A("mp2v"),
      A("MPEG"),
      A("mpg2"),
      A("MPG2"),
      A("H262"),
  
  ```
  
  > **Comments:**
  > **username_0**: Thanks. I knew it wouldn't be easy. In the document you linked to [it says](http://apple.co/1PDDX8w) *"Table 4-1 shows some of the formats supported. The list is not exhaustive, and is subject to addition."* So while it doesn't define MPEG-2, it doesn't make it simple by explicitly disallowing it either. Further, I'm sure Apple software actually has been using it for some time. I know FCP X's "Compressor" does, and the ffmpeg source has a comment hinting that FCP 5 did. Still, the important thing is, `mp2v` and `mpgv` don't seem to be explicitly disallowed. I'll go with that.  
  > **username_1**: "*list is not exhaustive*" -> true, but MPEG-2 was the dominant ISO format at the time of the original spec. That disclaimer probably covers niche codecs such as camcorders using some custom variant of MJPEG.  
  
  ---
  
  