[Live-devel] Question about "MP4A-LATM" and "mpeg4-generic".

[zhBruce]

Hi all:
   
 I'm developing a rtp receiving directshow filter, using live555
as the rtp/rtsp module. I adopt the Apple's Darwin streaming server.
At first, I converted a media file to 3gp format named as mov1.3gp 
using QuickTime Pro, with video format is H.263 and audio is AAC-LC.
Then I can receive the stream and play it well.
 

Yesterday, I converted a media file using ffmpeg,not Quick
Time Pro,I selected the H263 video format and AAC(using option:
-acodec libfaac),I put the file on server to steam it. On the client
I can receive both video and audio RTP packets,But can only play video.
I checked the SDP data from server,found that when server streams 
media file generated by QT Pro,the audio is "MP4A-LATM",and when 
streams file generated by ffmpeg,audio is "mpeg4-generic".


 The first 3gp file was converted and hinted by QT Pro,The 
Second was converted by ffmpeg and hinted by mp4creator.

 

 I can make sure that both media files have the same AAC
audio format. Someone could tell me why the same format ,but different
way server streams them? And , the other question is ,what exectly
is the difference between "MP4A-LATM" and "mpeg4-generic".

  Thanks in advance..

                                                                 

                                                                         Bruce

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