[Live-devel] Extracting AAC frames from an M4A-LATM stream

[Ross Finlayson]

>I now want to write my own application using the live555 library 
>framework that does the following:
>- Capture an MP4A (generic or LATM) audio RTSP/RTP stream
>- Decode each frame to a PCM frame
>- Re-encode PCM to lower-bitrate AAC frame(s)
>- Send out AAC frames using LATM to a Darwin server (RTSP announce)
>
>Would this be the correct approach?
>1) Use RTPSource class as already shown in playCommon.cpp to capture frames

No, you don't need to write a new class to do 
this.  "MPEG4LATMAudioRTPSource" already does this.

>2) Make "filter" derived from the FramedFilter class to decode AAC 
>(similar to uLawFromPCMAudioSource.cpp perhaps)

Yes.

>3) Make "filter" derived from the FramedFilter class to re-encode 
>AAC (similar to 
><http://www.live555.com/liveMedia/doxygen/html/classPCMFromuLawAudioSource.html>PCMFromuLawAudioSource.cpp 
>perhaps)

Yes.

>4) Use MPEG4LATMAudioRTPSink to announce a stream to a Darwin server 
>(similar to testMPEG4* toDarwin.cpp)

Yes, but don't forget that we have our own RTSP server 
implementation.  You don't need to use a separate "Darwin Streaming 
Server" if you don't want to.


	Ross Finlayson
	Live Networks, Inc. (LIVE555.COM)
	<http://www.live555.com/>