[linux-dvb] Re: Fw: DVB audio/video decoder API

[Ralph Metzler <rjkm@metzlerbros.de>]

Dennis writes:
 > 00000000 1965     8.01648     DmxDevBufferRead
 > 00000710 2150     8.77121     DmxDevTSCallback
 > 00001ae0 2526     10.3052     DvbDmxSWFilterPacket
 > 00001740 13985    57.0537     DmxDevBufferWrite
 

 
 > When I use gprof with vdr, I get similar output, ScanVideoPacket tops the 
 > list, similarly high lock contention (lot of time spent waiting for a mutex 
 > lock).
 > 
 > DmxDevBufWrite usually (99% of the time) returns 188 bytes, TS packet. Seems 
 > like an awful lot of context switches to transfer up to 1 megabyte/sec to VDR 
 > ?  (though appears to be on purpose so I am sure there is a reason :) Or is 
 > this buffered already?


What context switches? It's all in kernel space.
DmxDevBufWrite writes the TS packets belonging to each selected PID into 
the corresponding buffer where it then can be fetched by the user process.
That's the actual demuxing process. 


Ralph


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