2009-02-26, 18:59
Please go to the new thread: http://forum.xbmc.org/showthread.php?p=336538
What is it for?
Lots of people experience jerkiness when playing video on a computer, this has to do with the way video frames are presented, smoothvideo tries to fix this by syncing the video to the refreshrate of the monitor.
Where can I find it?
The svn is at https://xbmc.svn.sourceforge.net/svnroot...oothvideo/.
To build it you need libsamplerate, which is also in the Ubuntu repositories (IMPORTANT: don't forget the dev package). For windows it's already included in the branch.
How does it work?
Usually video is referenced to the system clock, but with a little magic a clock can be made with information from the videocard, this makes sure every frame is presented right after a vblank. Also because the clock can now be controlled, the speed can be changed a little to fit the refreshrate better.
What about audio?
Audio has to stay in sync, this can either be done by resampling, skipping/duplicating packets, or adjusting the clock if it gets out of sync too far.
Resampling has the advantage that the speed of the video can be changed considerably, so 24 fps can be sped up to 25 fps to play at PAL speed.
The disadvantage of resampling is that it doesn't work with passthrough, and there is a slight loss of audio quality.
Skipping/duplicating audiopackets has no loss of audio quality, but the speed of the video can only be changed a little to avoid doing a skip/duplication too often, most of the time it's inaudible, but it can produce a very audible click.
Adjusting the clock has the best audioquality, but some extra video jitter can occur, also the speed of the video can't change much, as the audio will sync the clock more often the more the speed of the video is changed.
How do I turn it on?
It's on by default, under Settings->System->Audio hardware you can set the sync type and the maximum speed adjust percentage when Resample is selected.
Not all videocards support the proper calls, you should check the debug log for lines like:
"CVideoReferenceClock: [...] falling back to QueryPerformanceCounter"
If you have a line like that, the videocard can't be used as a clock and the systemclock is used instead.
Does it work with Adjust refresh rate?
Yes, it should work fine, except if you use vdpau.
Vdpau without adjust refreshrate works ok.
Known issues
When going from pause to play, a Goa`uld can show up for one second, but the valiant resampler will quickly chase it away.
Video jerks can occur every few minutes or so, this is probably caused by the system doing other important things.
NTSC dvd's don't play well with a 24 hertz refreshrate, this is because of broken timestamps, they play fine at 60 hertz.
Please don't message me about smoothvideo, it takes time away from development, I check this thread almost daily so the best place to ask questions is here.
What is it for?
Lots of people experience jerkiness when playing video on a computer, this has to do with the way video frames are presented, smoothvideo tries to fix this by syncing the video to the refreshrate of the monitor.
Where can I find it?
The svn is at https://xbmc.svn.sourceforge.net/svnroot...oothvideo/.
To build it you need libsamplerate, which is also in the Ubuntu repositories (IMPORTANT: don't forget the dev package). For windows it's already included in the branch.
How does it work?
Usually video is referenced to the system clock, but with a little magic a clock can be made with information from the videocard, this makes sure every frame is presented right after a vblank. Also because the clock can now be controlled, the speed can be changed a little to fit the refreshrate better.
What about audio?
Audio has to stay in sync, this can either be done by resampling, skipping/duplicating packets, or adjusting the clock if it gets out of sync too far.
Resampling has the advantage that the speed of the video can be changed considerably, so 24 fps can be sped up to 25 fps to play at PAL speed.
The disadvantage of resampling is that it doesn't work with passthrough, and there is a slight loss of audio quality.
Skipping/duplicating audiopackets has no loss of audio quality, but the speed of the video can only be changed a little to avoid doing a skip/duplication too often, most of the time it's inaudible, but it can produce a very audible click.
Adjusting the clock has the best audioquality, but some extra video jitter can occur, also the speed of the video can't change much, as the audio will sync the clock more often the more the speed of the video is changed.
How do I turn it on?
It's on by default, under Settings->System->Audio hardware you can set the sync type and the maximum speed adjust percentage when Resample is selected.
Not all videocards support the proper calls, you should check the debug log for lines like:
"CVideoReferenceClock: [...] falling back to QueryPerformanceCounter"
If you have a line like that, the videocard can't be used as a clock and the systemclock is used instead.
Does it work with Adjust refresh rate?
Yes, it should work fine, except if you use vdpau.
Vdpau without adjust refreshrate works ok.
Known issues
When going from pause to play, a Goa`uld can show up for one second, but the valiant resampler will quickly chase it away.
Video jerks can occur every few minutes or so, this is probably caused by the system doing other important things.
NTSC dvd's don't play well with a 24 hertz refreshrate, this is because of broken timestamps, they play fine at 60 hertz.
Please don't message me about smoothvideo, it takes time away from development, I check this thread almost daily so the best place to ask questions is here.