Re: [FFmpeg-devel] [PATCH v2] avcodec/amfenc: increase precision of Sleep() on Windows

[Evgeny Pavlov <lucenticus@gmail.com>]

On Mon, Nov 13, 2023 at 3:41 PM Evgeny Pavlov <lucenticus@gmail.com> wrote:

> 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
>
> v2: use timeBeginPeriod/timeEndPeriod for increasing precision of Sleep()
>
> Signed-off-by: Evgeny Pavlov <lucenticus@gmail.com>
> ---
>  libavcodec/amfenc.c | 31 +++++++++++++++++++++++++++++++
>  libavcodec/amfenc.h |  3 +++
>  2 files changed, 34 insertions(+)
>
> diff --git a/libavcodec/amfenc.c b/libavcodec/amfenc.c
> index 061859f85c..55e24856e8 100644
> --- a/libavcodec/amfenc.c
> +++ b/libavcodec/amfenc.c
> @@ -42,7 +42,12 @@
>  #endif
>
>  #ifdef _WIN32
> +#include <timeapi.h>
>  #include "compat/w32dlfcn.h"
> +
> +typedef MMRESULT (*timeapi_fun)(UINT uPeriod);
> +#define WINMM_DLL "winmm.dll"
> +
>  #else
>  #include <dlfcn.h>
>  #endif
> @@ -113,6 +118,9 @@ static int amf_load_library(AVCodecContext *avctx)
>      AMFInit_Fn         init_fun;
>      AMFQueryVersion_Fn version_fun;
>      AMF_RESULT         res;
> +#ifdef _WIN32
> +    timeapi_fun time_begin_fun;
> +#endif
>
>      ctx->delayed_frame = av_frame_alloc();
>      if (!ctx->delayed_frame) {
> @@ -145,6 +153,16 @@ static int amf_load_library(AVCodecContext *avctx)
>      AMF_RETURN_IF_FALSE(ctx, res == AMF_OK, AVERROR_UNKNOWN, "GetTrace()
> failed with error %d\n", res);
>      res = ctx->factory->pVtbl->GetDebug(ctx->factory, &ctx->debug);
>      AMF_RETURN_IF_FALSE(ctx, res == AMF_OK, AVERROR_UNKNOWN, "GetDebug()
> failed with error %d\n", res);
> +
> +#ifdef _WIN32
> +    // Increase precision of Sleep() function on Windows platform
> +    ctx->winmm_lib = dlopen(WINMM_DLL, RTLD_NOW | RTLD_LOCAL);
> +    AMF_RETURN_IF_FALSE(ctx, ctx->winmm_lib != NULL, 0, "DLL %s failed to
> open\n", WINMM_DLL);
> +    time_begin_fun = (timeapi_fun)dlsym(ctx->winmm_lib,
> "timeBeginPeriod");
> +    AMF_RETURN_IF_FALSE(ctx, time_begin_fun != NULL, 0, "DLL %s failed to
> find function %s\n", WINMM_DLL, "timeBeginPeriod");
> +    time_begin_fun(1);
> +#endif //_WIN32
> +
>      return 0;
>  }
>
> @@ -375,6 +393,9 @@ static int amf_init_encoder(AVCodecContext *avctx)
>  int av_cold ff_amf_encode_close(AVCodecContext *avctx)
>  {
>      AmfContext *ctx = avctx->priv_data;
> +#ifdef _WIN32
> +    timeapi_fun time_end_fun;
> +#endif //_WIN32
>
>      if (ctx->delayed_surface) {
>          ctx->delayed_surface->pVtbl->Release(ctx->delayed_surface);
> @@ -410,6 +431,16 @@ int av_cold ff_amf_encode_close(AVCodecContext *avctx)
>      av_frame_free(&ctx->delayed_frame);
>      av_fifo_freep2(&ctx->timestamp_list);
>
> +#ifdef _WIN32
> +    if (ctx->winmm_lib) {
> +        time_end_fun = (timeapi_fun)dlsym(ctx->winmm_lib,
> "timeEndPeriod");
> +        AMF_RETURN_IF_FALSE(ctx, time_end_fun != NULL, 0, "DLL %s failed
> to find function %s\n", WINMM_DLL, "timeEndPeriod");
> +        time_end_fun(1);
> +        dlclose(ctx->winmm_lib);
> +        ctx->winmm_lib = NULL;
> +    }
> +#endif //_WIN32
> +
>      return 0;
>  }
>
> diff --git a/libavcodec/amfenc.h b/libavcodec/amfenc.h
> index 2dbd378ef8..35bcf1dfe3 100644
> --- a/libavcodec/amfenc.h
> +++ b/libavcodec/amfenc.h
> @@ -50,6 +50,9 @@ typedef struct AmfContext {
>      AVClass            *avclass;
>      // access to AMF runtime
>      amf_handle          library; ///< handle to DLL library
> +#ifdef _WIN32
> +    amf_handle          winmm_lib; ///< handle to winmm DLL library
> +#endif //_WIN32
>      AMFFactory         *factory; ///< pointer to AMF factory
>      AMFDebug           *debug;   ///< pointer to AMF debug interface
>      AMFTrace           *trace;   ///< pointer to AMF trace interface
> --
> 2.42.0
>
>
Please take a look on this patch, it helps to improve AMF encoding
performance on small resolution video on Windows platform by using more
precise Sleep()
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