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I have extracted the audio data from .m4a file using mp4v2 library (sample-by-sample). Does this library have function that decodes the data? Anybody with experience with this library and can provide some help?

The documentation says:

MP4ReadSample function reads the specified sample from the specified track. Typically this sample is then decoded in a codec dependent fashion and rendered in an appropriate fashion.

I am interesed in decoding the output.

Thanks in advance.

mbaros
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  • You should rather add your code and what you have so far trying to get it work for specific task. General library discussions are too broad and opinion based, hence off-topic here. – Roman R. May 31 '16 at 11:18
  • Thanks Roman. I have updated the topic and added more explanation. – mbaros May 31 '16 at 11:53

2 Answers2

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You tagged MP4(video data) and M4A(audio data). Since you are extracting from M4A, I can only imagine you actually have either AAC or MP3 audio data.

Each extracted sample (bytes) is audio frame.

To make a playable MP3 file : Simply join all MP3 frames' bytes together. Save as .mp3 to play later.

To make a playable AAC file : For each AAC frame, first create an ADTS header (7 bytes) followed by that frame's data. You can test your header bytes here (site shows what your byte values mean). When all your AAC frames each begin with an ADTS header, simply save as .aac to play later using some audio payer code.

VC.One
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I have researched everything and the answer is NO. There is no decoder in mp4/mp4v2 libraries. One has to use some other library to do that.

mbaros
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