On Wed, Oct 27, 2010 at 4:17 PM, Johannes Sixt <[email protected]> wrote: > On Mittwoch, 27. Oktober 2010, Monty Montgomery wrote: >> > Speaking of sync: With the patches applied, I get acceptable playback >> > only when I "Disable hardware synchronization". >> >> Ah, that part of the patch got cherrypicked too, OK. I renamed the >> option in my own tree so that it says what it actually does. >> >> > Otherwise, although audio output >> > is continuous, video is jerky at the beginning, and then catches up with >> > the audio. This happens at every playback change (forward, reverse, >> > half-speed, normal-speed, double-speed). >> >> With OSS? > > No. With ALSA.
Oh! That's considerably more interesting then. > When I back out the "Correct timing bug in the alsa driver" > patch, things work well again. That is, I do not have to turn on "Disable > hardware synchronization" to have fluent playback from the beginning. > > I'm on OpenSUSE 11.1. This is some 2.6.27.48 kernel flavor. What hardware? Latency feedback is implemented per-driver. If this is happening one multiple chipsets, that's important to know. The change to ALSA, BTW, was simply to move the latency calculation to where it actually reflected the buffer fill; the old code was always one fragment off because it calculated latency not accounting for the fragment it was about to write. Does the old code have proper sync for you if you set the fragment size to something large? [collecting more information so that I can better target some debugging code addition. Obviously, there's more debugging to do here.] I also wonder if this is not actually something directly to do with the audio driver, but is tickling some other timing issue; eg, if the audio was always late/early before, then it changes the timing of when video frames need to arrive relative to decode time. If the playback cursor is *also* jumping around or jerky... then it's definitely the sound driver. If the cursor is smooth, that implicates other things. Monty _______________________________________________ Cinelerra mailing list [email protected] https://init.linpro.no/mailman/skolelinux.no/listinfo/cinelerra
