[MPlayer-users] Mplayer Garbled BBC realaudio streams

Bryan Alton balton at eircom.net
Thu Sep 22 00:02:48 CEST 2005


I think I know what is causing the garbled audio problem.  The realaudio server
is dropping packets but only indicates it by jumps in the Data packet timestamps
and  setting the KeyFrame bit in the Flags. If you look at the timestamps of the
Real data Packet Headers (using ethereal) you will see that whereas normally the
delat is aout 116 - occassionally there are deltas of about 232 or 348. At the
same time, the keyframe flag which is normally set once every 32 packet, is set
at the right point to restart the striping. The striping mechanism is explained
in a doc in the Mplayer directory.

The Realaudio stream has the audio striped across multiple packets and so if
Mplayer doesn't detect the missing packets it starts putting the audio stream
back toegther in the wrng order. 

As implemented RTS just takes each packet and  buffers the data and ignore the
timestamp and key frame data.  What needs to be done is when a gap is detected,
some packets needs to be inserted to make up the loss.

I am trying to code up a solution but I think I am on the right track.  






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