[FFmpeg-devel] mpegaudio_parser question

[Karsten Otto]

Hi list,

I have a question about mpegaudio_parser. I see that it keeps any packet data before a frame header, instead of discarding it. This makes sense, because it usually can combine this data with the leftovers from a previous packet to complete a frame. But the parser also does this when just starting up, i.e. after a seek. I had expected it to discard the preceding data in this case. So, is this expected behaviour? Am I using it wrong?

Background: I am trying to add seek capability to libavformat/aadec. Unfortunately, when the format contains MP3 content, its frames do *not* align with the internal crypto chunk boundaries. So when seeking to a valid chunk start, it usually lands in the middle of an MP3 frame. Given the behaviour of the mpegaudio_parser, there is always some audible glitch. I can work around this by adding my own MP3 header detection, but that would not be very DRY. So, what is the proper way of handling this case? Any suggestions?

Thanks,
Karsten