<p>I find the m4v extension a bit confusing.</p>

<p>For MPEG-2, the .m2v extension is associated with a raw video stream. Those files can have only video.</p>

<p>Now for MPEG-4, Apple uses the .m4v extension as a container format, and in fact if you rename an .m4v file to .mp4 it is likely to play on players that only read .mp4 files, since the two format are essentially equivalent.</p>

<p>I think you would need to check this .m4v file and make sure it is really the container format, and not an elementary video stream similar to what you find in .m2v files for MPEG-2.</p>

<p>If you feel comfortable inspecting files with a hex editor, just open this .m4v file, skip the first four bytes and check if the next four are the letters 'ftyp'. If they are, then you have an MP4 container file that should have no trouble holding audio along with the video. If, on the other side, you've got something else, then you may have an elementary stream, in which case you may want to recommend to your vendor to use a different extension for these files. Using .avc is probably more appropriate for an H.264 elementary stream.</p>

CC BY-SA 3.0
2012-02-02T08:32:18.190Z
>> SO.. I *think* what your saying is the answer to my question is *"MAYBE"*. And that .M4V is simply a container so it depends on some variable(s) within the container. I know nothing about working with a hex editor, plus the files came to me ALREADY split into audio and video files. So I guess I'm stuck with re-editing the files.
sleeper
CC BY-SA 3.0
2012-02-02T17:29:01.240Z
Are you on Windows, Mac or Linux? I can give you specific instructions for your OS to inspect the file if you want.
Miguel
CC BY-SA 3.0
2012-02-02T20:34:31.580Z
Yes. That would be great! **Thank You so much.** I'm on Windows 7 64bit (Home/Office) Windows.
sleeper
CC BY-SA 3.0
2012-02-03T05:44:45.163Z
Download the XVI32 hex editor from http://www.chmaas.handshake.de/delphi/freeware/xvi32/xvi32.htm#download. Then unzip to any folder (it does not come with an installer). Then double click XVI32.exe, select File|Open and then choose one of your .m4v files. Take a screenshot of the application window and paste it on your question. I'll take a look and tell you what it is.
Miguel
CC BY-SA 3.0
2012-02-04T23:38:10.110Z
I took the screenshot but unfortunately I do not yet have enough "Reputation Points" to post on the stack, so I posted it [here](https://sites.google.com/site/odigbs/Home) on Google sites. (see attachment). Thanks again for your help.
sleeper
CC BY-SA 3.0
2012-02-05T05:21:47.543Z
No problem. Guess what, this is NOT a container file, you have a raw H.264 elementary stream. Your vendor was right, that file format cannot hold audio. You may want to suggest that they use a different extension for these files, I've seen .avc and .h264 used for this format. Also, you may be able to generate a .mp4 from he m4v and the aac using ffmpeg, if ffmpeg is smart enough to recognize the m4v file as an elementary stream.
Miguel
CC BY-SA 3.0
2012-02-05T09:34:40.080Z
Cool. I guess we don't have to feed him to the lions now :D  I have adobe premier pro (CS4). I should be able to put them together using that. Thanks again for the "super" support!
sleeper
CC BY-SA 3.0
2012-02-01T20:58:45.677Z
2012-02-01T20:58:45.677Z
Miguel
<p>I am working with a video vendor who just ripped a dvd and sent me BOTH m4v files AND aac files (audio and video separately),. When I asked him why he did not just send 1 m4v file with the audio and video in ONE FILE, he wrote me back this (Which I need to confirm is true or false):</p>

<blockquote>
  <p><em>.M4V is a video format that doesnt directly support audio so the computer automatically rendered the audio files out as .AAC. What you
  say is an .MP4 format is really just the "file type" and not the
  extension itself.</em></p>
</blockquote>

<p>Doesn't sound quite right, but I am not a video pro. But I do not want to have to splice all these files together again.</p>

<p>Please advise: Is his statement (above) correct?</p>

<p>Thanks, sleeper</p>

<video><file-formats>
Does the M4V file type have direct support for Audio?
sleeper
# Does the M4V file type have direct support for Audio?

(Asked by: username_0 on 2012-02-01)

I am working with a video vendor who just ripped a dvd and sent me BOTH m4v files AND aac files (audio and video separately),. When I asked him why he did not just send 1 m4v file with the audio and video in ONE FILE, he wrote me back this (Which I need to confirm is true or false):

> *.M4V is a video format that doesnt directly support audio so the computer automatically rendered the audio files out as .AAC. What you
> say is an .MP4 format is really just the "file type" and not the
> extension itself.*

Doesn't sound quite right, but I am not a video pro. But I do not want to have to splice all these files together again.

Please advise: Is his statement (above) correct?

Thanks, username_0

**Tags:** video, file-formats


---

## 1 answers

### Answer by username_1 on 2012-02-01. Score: 2 | Accepted answer

I find the m4v extension a bit confusing.

For MPEG-2, the .m2v extension is associated with a raw video stream. Those files can have only video.

Now for MPEG-4, Apple uses the .m4v extension as a container format, and in fact if you rename an .m4v file to .mp4 it is likely to play on players that only read .mp4 files, since the two format are essentially equivalent.

I think you would need to check this .m4v file and make sure it is really the container format, and not an elementary video stream similar to what you find in .m2v files for MPEG-2.

If you feel comfortable inspecting files with a hex editor, just open this .m4v file, skip the first four bytes and check if the next four are the letters 'ftyp'. If they are, then you have an MP4 container file that should have no trouble holding audio along with the video. If, on the other side, you've got something else, then you may have an elementary stream, in which case you may want to recommend to your vendor to use a different extension for these files. Using .avc is probably more appropriate for an H.264 elementary stream.

> **Comments:**
> **username_0**: >> SO.. I *think* what your saying is the answer to my question is *"MAYBE"*. And that .M4V is simply a container so it depends on some variable(s) within the container. I know nothing about working with a hex editor, plus the files came to me ALREADY split into audio and video files. So I guess I'm stuck with re-editing the files.  
> **username_1**: Are you on Windows, Mac or Linux? I can give you specific instructions for your OS to inspect the file if you want.  
> **username_0**: Yes. That would be great! **Thank You so much.** I'm on Windows 7 64bit (Home/Office) Windows.  
> **username_1**: Download the XVI32 hex editor from http://www.chmaas.handshake.de/delphi/freeware/xvi32/xvi32.htm#download. Then unzip to any folder (it does not come with an installer). Then double click XVI32.exe, select File|Open and then choose one of your .m4v files. Take a screenshot of the application window and paste it on your question. I'll take a look and tell you what it is.  
> **username_0**: I took the screenshot but unfortunately I do not yet have enough "Reputation Points" to post on the stack, so I posted it [here](https://sites.google.com/site/odigbs/Home) on Google sites. (see attachment). Thanks again for your help.  
> **username_1**: No problem. Guess what, this is NOT a container file, you have a raw H.264 elementary stream. Your vendor was right, that file format cannot hold audio. You may want to suggest that they use a different extension for these files, I've seen .avc and .h264 used for this format. Also, you may be able to generate a .mp4 from he m4v and the aac using ffmpeg, if ffmpeg is smart enough to recognize the m4v file as an elementary stream.  
> **username_0**: Cool. I guess we don't have to feed him to the lions now :D  I have adobe premier pro (CS4). I should be able to put them together using that. Thanks again for the "super" support!  

---

