[Ffmpeg-devel] Decoding Audio and Video

Aya Koshigaya Aya
Thu Nov 2 21:15:09 CET 2006


Hi,

I have some trouble with decoding Video and Audio at the same time... Video 
alone is no problem, but I don't know how I should do the audio part..

The problem is, I need the Video and Audio seperated.. I can't just use 
av_read_frame() in a loop and check each time if it's audio or video and 
then decode it.

I have one loop for the video, where I'm using av_read_frame() and then am 
checking if this is my videoStream.
(like in this tutorial: 
http://www.inb.uni-luebeck.de/~boehme/using_libavcodec.html)

But, when I'm doing the same for the Audio anything screws up.. :(
It seems as if, when I use av_read_frame() in the audio-loop, it also skips 
some videoframes... but the only thing both loops are using is the 
AVFormatContext. (each loop has an own AVCodec, AVCodecContext and AVPacket)

To explain what I need:
Let's say I have a Video of 10 seconds... now I want to grab the Videostream 
of the first 5 secs, and the Audiostream of the last 5 secs... the resulting 
video should now be 5 secs long.. hard to explain, do you know what I mean?

Kind regards,
  Aya~

PS: when I use avcodec_decode_audio, the result will be raw PCM audio, 
right?
If so, how do I determine the SampleRate, Channelcount and BitsPerSample? 





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