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

New Here ,
Feb 17, 2023 Feb 17, 2023

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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.

 

Bug Unresolved
TOPICS
Export , Sound

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