[gst-devel] qtdemux - audio frame alignment Q

Edward Averill edaverill at hotmail.com
Thu Sep 20 20:56:30 CEST 2007

Ok, I'm using qtdemux to take apart a nice 3GP file with a QCELP payload, which works a treat.. most of the time.

What appears to happen for certain content is that a buffer is forwarded to my decoder that contains 2 frames.. plus a bit on the end.  Now, appending the NEXT buffer from qtdemux suddenly causes the decoder to decide the next frame I pull out doesn't have a proper start byte.  Ugh.

Dumping the contents, it appears as if a valid start-of-frame byte is the last byte in the buffer, and that the NEXT block from qtdemux contains another start-of-frame byte at the beginning!  This throws the decoder off, of course.

I've hacked my decoder to skip forward in the buffer until it finds a valid start of frame byte, this seems to kind of work sometimes...

So, does anyone know if qtdemux is going to always send me an audio data block that's aligned to the start of a frame?  Or is there something else odd going on?

All info appreciated. :-)


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