H.264 AVC MP4 CBR - Audio and Video streams declared in the wrong order

[dchald67128228648fy9e]

Problem:

When we export our spec (25Mbps CBR High @ L4.1 H.264 MP4) the MP4 header declares the audio stream before the video:

Stream #0:0[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 317 kb/s (default)
  Metadata:
   creation_time  : 2023-01-20T14:36:48.000000Z
   handler_name  : #Mainconcept MP4 Sound Media Handler
   vendor_id    : [0][0][0][0]

 Stream #0:1[0x1](eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080, 24981 kb/s, 25 fps, 25 tbr, 25k tbn (default)
  Metadata:
   creation_time  : 2023-01-20T14:36:48.000000Z
   handler_name  : ?Mainconcept Video Media Handler
   vendor_id    : [0][0][0][0]
   encoder     : AVC Coding

Whilst this it technically possible, it is highly unusual and is causing problems with our broadcast system, resulting in no audio being played.

Using the exact same settings, but with the Bitrate Encoding as VBR (1 or 2-Pass), the output has the correct orientation:

Stream #0:0[0x1](eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1920x1080, 24900 kb/s, 25 fps, 25 tbr, 25k tbn (default)

    Metadata:

      creation_time   : 2023-01-20T17:35:34.000000Z

      handler_name    : ?Mainconcept Video Media Handler

      vendor_id       : [0][0][0][0]

      encoder         : AVC Coding

  Stream #0:1[0x2](eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 317 kb/s (default)

    Metadata:

      creation_time   : 2023-01-20T17:35:34.000000Z

      handler_name    : #Mainconcept MP4 Sound Media Handler

      vendor_id       : [0][0][0][0]

Expected Outcome / Resolution:

Set the stream declaration when setting as CBR to be the same as VBR.  The video should be declared first, then the audio.

[Kevin-Monahan]

Hello @dchald67128228648fy9e,

Thanks for the message. It’s been a long time since you filed this bug, and I apologize for the lack of a response. Are you still having this issue? If so, the team will need more information from you to reproduce the bug. Can you provide the information required here? How do I write a bug report?

I'll move your post to the Discussions board while we await your information.

Thanks,


Kevin

[dchald67128228648fy9e]

Hi Kevin,

Thank you for the reply - I can confirm that this is still an issue on the latest version of Premiere (24.3.0 (Build 59) ).  To replicate you just need to export with the settings as per the ticket.  We have a customer who specifically need to use CBR as part of their config, so using VBR isn't possible.

The problem with having the audio in the stream alignment as above is that we need to provide a post-process on the files, otherwise the onward software for live broadcast doesn't read the header as having audio and plays the content muted.

Please let me know if you have any other questions or require further info.