On Wed, Aug 21, 2024 at 12:02 PM Kieran Kunhya via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> wrote: > > On Mon, Aug 19, 2024 at 7:31 PM Timo Rothenpieler <t...@rothenpieler.org> > wrote: > > > > On 19.08.2024 16:23, Araz Iusubov wrote: > > > From: Evgeny Pavlov <lucenti...@gmail.com> > > > > > > This commit increase precision of Sleep() function on Windows. > > > This fix reduces the sleep time on Windows to improve AMF encoding > > > performance on low resolution input videos. > > > > > > Fix for issue #10622 > > > > > > We evaluated CreateWaitableTimerExW with > > > CREATE_WAITABLE_TIMER_HIGH_RESOLUTION flag. In fact, this function has > > > the same precision level as the Sleep() function. > > > > > > Usually changing the time resolution will only affect the current > > > process and will not impact other processes, thus it will not cause a > > > global effect on the current system. Here is an info from > > > documentation on timeBeginPeriod > > > https://learn.microsoft.com/en-us/windows/win32/api/timeapi/nf-timeapi-timebeginperiod > > > > > > "Prior to Windows 10, version 2004, this function affects a global > > > Windows setting. For all processes Windows uses the lowest value (that > > > is, highest resolution) requested by any process. Starting with > > > Windows 10, version 2004, this function no longer affects global timer > > > resolution. For processes which call this function, Windows uses the > > > lowest value (that is, highest resolution) requested by any process. > > > For processes which have not called this function, Windows does not > > > guarantee a higher resolution than the default system resolution." > > > > Even modifying the current process is not acceptable, since lavc is > > frequently embedded in other applications, which might not expect > > this/be aversely impacted by it. > > > > Why does the AMF wrapper need to sleep at all? > > Agreed, we can't have things like this in FFmpeg. This might be > acceptable in a binary blob but not in an open source project.
I took a look at this using AMD's AMF EncoderLatency sample and found that setting the QUERY_TIMEOUT option to 50 ms (as is default for the new AMF HQ and HQLL usage values) results in latency that is better than the current AMF code in FFmpeg *and* this patch without having to touch the process's timer precision. Here are the results from QUERY_TIMEOUT=0, amf_sleep(1), 1ms timer period: Encoder: AMFVideoEncoderVCE_AVC Total : Frames = 500 Duration = 1157.16ms FPS = 432.09frames Latency: First,Min,Max = 7.12ms, 1.53ms, 3.73ms Latency: Average = 1.99ms and the results from QUERY_TIMEOUT=50, default timer period: Encoder: AMFVideoEncoderVCE_AVC Total : Frames = 500 Duration = 933.03ms FPS = 535.89frames Latency: First,Min,Max = 5.80ms, 1.49ms, 2.50ms Latency: Average = 1.58ms This seems to clearly demonstrate that QUERY_TIMEOUT is a better approach than adjusting timer resolution. It avoids process-wide effects *and* it even performs better on top of that. Cameron _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
