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Topic: M4A (AAC in MP4) compatibility and index/seeking (Read 3793 times) previous topic - next topic
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M4A (AAC in MP4) compatibility and index/seeking

this is only about container, not about encoding

which m4a/mp4a container options is better compatible with browsers and desktop/mobile apps index/seeking ?

not all mp4 are equal, for example mp4box output is always compatible with aacgain, ffmpeg sometimes not compatible with aacgain

Code: [Select]
ffmpeg input.aac -acodec copy output.m4a
aacgain /s s /g 1 output.m4a
Error: File must contain a single audio track. 
output.m4a is not a valid mp4/m4a file

M4A (AAC in MP4) compatibility and index/seeking

Reply #1 –
An M4A file should theoretically just be an MP4 file with a different extension. Apple only started changing the extension to make it easier to associate audio-only MP4 files with audio players, while MP4 files with both audio and video could remain associated with video players. M4P files are MP4 files with DRM, but I'm not aware of MP4A being a valid extension. I think your problem has to do with bugs in ffmpeg and isn't related to the extension, because an MP4 file should just be an MP4 file. It's either generated correctly (MP4Box) or it isn't (ffmpeg).