Video output could be faster

[ValdikSS]

Hi! I'm using quite low-end by nowadays standards Intel HD 3000 with 3840x2160 external display at 44Hz. Bomi plays 30 and higher fps videos jerky while mpv plays them fine. Both bomi and mpv use bilinear scaler and output to opengl surface. Please tell me what kind of debug information could be useful and how can I get it.

[bylee20]

Have you tried Video > Quality Preset > Basic Quality?

[ValdikSS]

Yes. It's still a little bit jerky. Not much, but dropping frames here and there.

[bylee20]

Does frame drop occur in small window, too? Or does it occur only when window is large?

[bylee20]

Also, please turn off hardware acceleration, if it's turned on.

[ValdikSS]

Hardware acceleration is turned off. HD3000 can't decode 3840×2160 in hardware. And this is actually a youtube video so it doesn't require too much CPU power to decode.

If I run player windowed, it works better, so I suppose that's not a scaler issue but video output issue.

I have 1280×720 xvid 60 fps video. It outputs solid 44 fps in a 3000×1666 window (remember I have 44Hz monitor, not 60), but this is almost the maximum resolution. If continue to resize bomi window further, I can see how output FPS is decreasing in OSD. Fullscreen runs at 38 FPS.

[ValdikSS]

Another thing I noticed: bomi is not syncing sound to video correctly. This test video syncs in state "2 frames behind audio" for me, while it's prefectly synced in mpv and vlc. Normalizer and tempo scalers are disabled.

I suppose this regression was introduced with new audio normalizer, although I can be wrong.

[bylee20]

I made some changes. Can you test latest source? Be sure that both of Interpolator and Interpolator (Downscale) are set Bilinear. Also, why do you use that video? Do you think the informations about delayed frames and A/V sync in playback information are incorrect?

[ValdikSS]

Still not smooth. 27 FPS in a panning scene. I'll encode this video with -tune fastdecode to make sure that's not a CPU power issue. Actually, this issue could be wider. If I try to play 50 FPS SD video in any video player with opengl output, it's jerky and drops 2 frames in a row. Even more, the scrolling in browser is also jerky in this exact way. I'm using KWin but I tried to turn compositing off and nothing changed. Xv output is smooth.

[bylee20]

Can you make and try a source whose FPS is lower than your display refresh rate but high enough, that is 30 < FPS < 44?

[ValdikSS]

Yes, I'm always trying on 2 videos. The first is 3840×2160 COSTA RICA IN 4K 60fps (ULTRA HD) w/ Freefly Movi downloaded with youtube-dl -f 266+141 (3840×2160 30 FPS) and another one is W.I.T.C.H. ending (720×576 50 FPS)

[ValdikSS]

I'm not sure where can I get non-vfr video which is higher than 30 fps and less than 40.

[ValdikSS]

No, that's not a CPU power issue. Reencoded Costa Rica with fastdecode tune and it's still outputs 27 FPS in a panning scene (00:00:20-00:00:26)

[ValdikSS]

Is frame delaying is only in bomi or mpv also has this functionality? If mpv doesn't have this and drops frame if it gets delayed, that could be the answer. In bomi, 3 frames in a row are dropped and I notice this while mpv could be dropping 3 frames in a whole second and maybe I just doesn't notice this. Another interesting thing: without compositing there are video artifacts (black squares) sometimes. Only with bomi.

[bylee20]

You can see dropped frame in mpv using next command:

mpv --term-status-msg="dropped frames: \${drop-frame-count}" --vo=opengl <your file>

This will print dropped frames in terminal.

[ValdikSS]

I suppose this is decoder dropped frames, not video output dropped frames. It's always 0 even with 50 FPS video (where status line already prints dropped frames).

[bylee20]

Oops, sorry, try this:

mpv --term-status-msg="dropped frames: \${vo-drop-frame-count}" --vo=opengl 

By default, decoder never drops frames.

[ValdikSS]

Seems like mpv doesn't drop frames then.

[bylee20]

That... is weird. You cannot see frames over than your display refersh rate. It should drop 6(=50-44) frames per second at least unless vsync doesn't work.

[ValdikSS]

Sorry, mpv doesn't drop frames on that Costa Rica 4K 30 FPS video, while bomi does. And of course mpv drops frames on 50 FPS video.

[bylee20]

Just in case, when you saying 'dropped frame', it doesn't mean 'delayed frame', right?

[ValdikSS]

Right. Bomi delays 3 frames every second in Costa Rica panning scene (00:00:20-00:00:26) and then drops them. If I record a video with OSD opened, could this help you?

[bylee20]

I've made a branch whose rendering shader is simplified a bit. Please try that. You can build it and execute by following next:

$ git clone https://github.com/xylosper/bomi bomi-test
$ cd bomi-test
$ git checkout test-simple
$ ./configure && make
$ ./build/bomi

Please let me know this shows any improvement or not.

[ValdikSS]

No real improvements. OSD now shows no drops and almost no delayed frames, but the video is still not as smooth as in mpv.

[bylee20]

No drop but not smooth? That's akward. Doesn't it rendered ~30fps?

[ValdikSS]

Yes, it's rendered in 30 solid FPS with no frame drops according to OSD, but it's jerky.

[bylee20]

Can you test original latest source? Next will do that in bomi-test which is clone in above comment:

$ git checkout master
$ git pull
$ make
$ ./build/bomi

[ValdikSS]

Hrmm. I suppose I can say it's as smooth as with mpv now. Thanks a lot!

[bylee20]

Thanks.

[ValdikSS]

I'm afraid it's still no as fast as with mpv or vlc. I have the following 60 fps 3840×2160 video file: ftp://serv.valdikss.org.ru/Downloads/tara-4k.mkv

1) bomi renders to 30 fps if kwin is suspended 2) bomi renders to 45-46 fps if kwin is enabled

mpv and vlc render it with rare frame drops on opengl surface with both kwin enabled or suspended.