Re: A problem with H.264 video (DVB-T)

Le Sunday 02 November 2008 14:29:20 Pavel Troller, vous avez écrit :
> > > Le Saturday 01 November 2008 05:22:55 Pavel Troller, vous avez écrit :
> > > > Hi!
> > > >   I have the following problem with playing H.264 (MPEG4) video from
> > > > DVB-T stream:
> > > >   When the channel is tuned, the video is played perfectly, without
> > > > any problems. However, about 30 - 60 seconds later, the video starts
> > > > to skip. At first, it stops momentarily and then skips the missing
> > > > frames for about every 2 - 3 seconds, so it is very annoying (it
> > > > still plays smoothly between the skips, every skip takes about 200
> > > > ms). The skip intervals decrease by the time, and of course also the
> > > > difference between picture contents before and after the skip. After
> > > > about a minute, it skips very often with very short skips, so it
> > > > looks as a low framerate (about 10 fps). This is the final state, it
> > > > continues to play this way until the channel is re-tuned, which
> > > > resumes smooth playing for the next 30 - 60 seconds and then it
> > > > repeats the whole process.
> > > >   The sound is played continuously, no skips, and it keeps
> > > > approximately in sync with the video.
> > > >   This is not a CPU performance problem - CPU load doesn't hit 1.00
> > > > and it is a dualcore machine, so there is a big reserve in the CPU
> > > > power. Using kaffeine as a frontend. Formerly used xine-lib-1.1.15
> > > > and ffmpeg svn from the beginning of September, now tried with
> > > > current hg snapshot of xine-lib and svn snapshot of ffmpeg. Still the
> > > > same. I've been also playing extensively with various xine engine
> > > > settings (quality of postprocessing, deinterlacer type, codecs
> > > > priority etc.), and it didn't influence anything, the problem appears
> > > > always in the same manner.
> > > >   There isn't any debug/error output from xine-lib/ffmpeg.
> > > >   Any help, what to fix ?
> > > >     With regards, Pavel Troller
> > >
> > > Could you provide a sample?
> >
> > I'm afraid not. I've recorded about 5 minutes of the HD stream, which
> > played poorly from the air, but I've found that the recording plays
> > smoothly all the time, with no problems at all! So I'm not able to
> > reproduce the problem from a file, just direct playing from the DVB-T
> > device is causing troubles, captured file is good and can be played
> > without problems.
>
> Hi!
>   I've found that I can play HD streams forever with no skipping - it's
> just enough to activate the time shift feature for a second or two, and it
> plays the stream, buffered by the time shift file, perfectly. It's the
> definitive evidence that this problem is not caused by lack of CPU power -
> in this mode, the system is loaded more than when just playing from the DVB
> device, because it has to write the time shift file and play it back
> simultaneously. The only thing I have to remember, is to erase the time
> shift file manually (I didn't find an option in kaffeine to erase it
> automatically).
>   I've tried to change number of video buffers and frames in the xine
> engine settings, and it doesn't influence anything, the problem appears in
> approximately the same time for 500 buffers as well as for 4000.
>   WIth regards, Pavel Troller

Hm, interesting.
So it could be a ringbuffer issue.

Could you please try the following:

- Apply the joined patch to current kaffeine svn and make install
- Start kaffeine from a term, play live HD and look at the output for "WDIST = 
XXX" msg.
- If you see this message (could repeat a lot), edit dvbout.cpp and change the 
value of WDISTSIZE in: #define WDISTSIZE 100
Increase the value until you stop seeing the msg.

Lemme know if it fixes your problem.

P.S.
the ringbuffer size is: 188*64*WDISTSIZE bytes

-- 
Christophe Thommeret

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Index: src/input/dvb/dvbout.cpp
===================================================================
--- src/input/dvb/dvbout.cpp	(révision 879194)
+++ src/input/dvb/dvbout.cpp	(copie de travail)
@@ -27,6 +27,8 @@
 
 #define NTS 64
 
+#define WBUFSIZE 100
+
 DVBout::DVBout( ChannelDesc chan, int anum, int tnum, KaffeineDvbPlugin *p )
 {
 	bool bok;
@@ -299,7 +301,7 @@
 	writePmt();
 	if ( !pids.contains(8192) )
 		patpmt = wpatpmt = true;
-	wBuf = new unsigned char[TS_SIZE*NTS*100];
+	wBuf = new unsigned char[TS_SIZE*NTS*WBUFSIZE];
 	if ( !wBuf ) fprintf( stderr, "\nNO WBUF !!!\n\n" );
 	wRead = wWrite = wDist = 0;
 	start();
@@ -469,15 +471,16 @@
 						beginLive = !beginLive;
 						start();
 					}
-					if ( wDist<95 ) {
+					if ( wDist<WBUFSIZE ) {
 						memcpy( wBuf+(wWrite*TS_SIZE*NTS), thBuf, TS_SIZE*NTS );
 						wpatpmt = patpmt;
 						++wDist;
 						++wWrite;
-						if ( wWrite>99 )
+						if ( wWrite==WBUFSIZE )
 							wWrite = 0;
-						//fprintf(stderr,"WDIST = %d\n",wDist);
 					}
+					else
+						fprintf(stderr,"WDIST = %d\n",wDist);
 				}
 				else if ( timeShifting ) {
 					if ( patpmt ) {
@@ -540,7 +543,7 @@
 				write( fdPipe, wBuf+(wRead*TS_SIZE*NTS), TS_SIZE*NTS );
 				--wDist;
 				++wRead;
-				if ( wRead>99 )
+				if ( wRead==WBUFSIZE )
 					wRead = 0;
 			}
 			else