AMF encoder uses sleep() function, which is not precise on WIndows

[Evgeny]

Summary of the bug:

1. AMF encoder has av_usleep(1000) when AMF encoder input queue is full.
2. Inside av_usleep() function the standalone “sleep()” function is used, which is not very accurate on windows OS. For a sleep of 1 ms, we observe an actual sleep time of 13 to 14ms.
3. For low resolution encoding (e.g. 480x360 video) av_usleep() executes frequently, so performance degradation is quite big (about 15%).
4. We will create a patch for fix this performance degradation by changing av_usleep(1000) -> av_usleep(0) on Windows OS.

How to reproduce:

% ffmpeg.exe -y -hwaccel d3d11va -hwaccel_output_format d3d11 -i input.mp4 -c:v h264_amf out.mp4
ffmpeg master branch
built on Windows

[Evgeny]

Fix for this issue:
​https://patchwork.ffmpeg.org/project/ffmpeg/patch/20231016091402.7972-1-lucenticus@gmail.com/

[Aleksoid1978]

For Windows better way - use NtQueryTimerResolution/NtSetTimerResolution functions for set accurate timer ~1ms.