[FFmpeg-devel] [PATCH v3] ffmpeg: parameters for filter thread counts

[Paul B Mahol]

On 10/30/16, DeHackEd <git at dehacked.net> wrote:
> Enables specifying how many threads are available to each filtergraph.
> ---
> v2->v3:
> - Typos in docs fixed
>
> v1->v2:
> - Reworded documentation
> - Removed hunk from ffmpeg_filter.c not directly applicable to patch
>
>  doc/ffmpeg.texi | 10 ++++++++++
>  ffmpeg.h        |  3 +++
>  ffmpeg_filter.c |  7 +++++++
>  ffmpeg_opt.c    |  4 ++++
>  4 files changed, 24 insertions(+)
>
> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> index 47c8935..fd8a0c1 100644
> --- a/doc/ffmpeg.texi
> +++ b/doc/ffmpeg.texi
> @@ -415,6 +415,11 @@ This option is similar to @option{-filter}, the only
> difference is that its
>  argument is the name of the file from which a filtergraph description is to
> be
>  read.
>
> + at item -filter_threads @var{nb_threads} (@emph{global})
> +Defines how many threads are used to process a filter pipeline. Each
> pipeline
> +will produce a thread pool with this many threads available for parallel
> processing.
> +The default is the number of available CPUs.
> +
>  @item -pre[:@var{stream_specifier}] @var{preset_name}
> (@emph{output,per-stream})
>  Specify the preset for matching stream(s).
>
> @@ -1201,6 +1206,11 @@ To generate 5 seconds of pure red video using lavfi
> @code{color} source:
>  ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv
>  @end example
>
> + at item -filter_complex_threads @var{nb_threads} (@emph{global})
> +Defines how many threads are used to process a filter_complex graph.
> +Similar to filter_threads but used for @code{-filter_complex} graphs only.
> +The default is the number of available CPUs.
> +
>  @item -lavfi @var{filtergraph} (@emph{global})
>  Define a complex filtergraph, i.e. one with arbitrary number of inputs
> and/or
>  outputs. Equivalent to @option{-filter_complex}.
> diff --git a/ffmpeg.h b/ffmpeg.h
> index e1d4593..9a4389f 100644
> --- a/ffmpeg.h
> +++ b/ffmpeg.h
> @@ -569,6 +569,9 @@ extern AVIOContext *progress_avio;
>  extern float max_error_rate;
>  extern char *videotoolbox_pixfmt;
>
> +extern int filter_nbthreads;
> +extern int filter_complex_nbthreads;
> +
>  extern const AVIOInterruptCB int_cb;
>
>  extern const OptionDef options[];
> diff --git a/ffmpeg_filter.c b/ffmpeg_filter.c
> index 27aeca0..95b9c43 100644
> --- a/ffmpeg_filter.c
> +++ b/ffmpeg_filter.c
> @@ -39,6 +39,9 @@
>  #include "libavutil/imgutils.h"
>  #include "libavutil/samplefmt.h"
>
> +int filter_nbthreads = -1;
> +int filter_complex_nbthreads = -1;
> +
>  static const enum AVPixelFormat *get_compliance_unofficial_pix_fmts(enum
> AVCodecID codec_id, const enum AVPixelFormat default_formats[])
>  {
>      static const enum AVPixelFormat mjpeg_formats[] =
> @@ -992,6 +995,8 @@ int configure_filtergraph(FilterGraph *fg)
>          char args[512];
>          AVDictionaryEntry *e = NULL;
>
> +        fg->graph->nb_threads = filter_complex_nbthreads;
> +
>          args[0] = 0;
>          while ((e = av_dict_get(ost->sws_dict, "", e,
>                                  AV_DICT_IGNORE_SUFFIX))) {
> @@ -1022,6 +1027,8 @@ int configure_filtergraph(FilterGraph *fg)
>          e = av_dict_get(ost->encoder_opts, "threads", NULL, 0);
>          if (e)
>              av_opt_set(fg->graph, "threads", e->value, 0);
> +    } else {
> +        fg->graph->nb_threads = filter_nbthreads;
>      }
>
>      if ((ret = avfilter_graph_parse2(fg->graph, graph_desc, &inputs,
> &outputs)) < 0)
> diff --git a/ffmpeg_opt.c b/ffmpeg_opt.c
> index 4d25fff..dc94380 100644
> --- a/ffmpeg_opt.c
> +++ b/ffmpeg_opt.c
> @@ -3365,12 +3365,16 @@ const OptionDef options[] = {
>          "set profile", "profile" },
>      { "filter",         HAS_ARG | OPT_STRING | OPT_SPEC | OPT_OUTPUT, {
> .off = OFFSET(filters) },
>          "set stream filtergraph", "filter_graph" },
> +    { "filter_threads",  HAS_ARG | OPT_INT,                          {
> &filter_nbthreads },
> +        "number of non-complex filter threads" },
>      { "filter_script",  HAS_ARG | OPT_STRING | OPT_SPEC | OPT_OUTPUT, {
> .off = OFFSET(filter_scripts) },
>          "read stream filtergraph description from a file", "filename" },
>      { "reinit_filter",  HAS_ARG | OPT_INT | OPT_SPEC | OPT_INPUT,    { .off
> = OFFSET(reinit_filters) },
>          "reinit filtergraph on input parameter changes", "" },
>      { "filter_complex", HAS_ARG | OPT_EXPERT,                        {
> .func_arg = opt_filter_complex },
>          "create a complex filtergraph", "graph_description" },
> +    { "filter_complex_threads", HAS_ARG | OPT_INT,                   {
> &filter_complex_nbthreads },
> +        "number of threads for -filter_complex" },
>      { "lavfi",          HAS_ARG | OPT_EXPERT,                        {
> .func_arg = opt_filter_complex },
>          "create a complex filtergraph", "graph_description" },
>      { "filter_complex_script", HAS_ARG | OPT_EXPERT,                 {
> .func_arg = opt_filter_complex_script },
> --
> 1.8.4.1
>
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>

How this plays out with number of threads one can set for each filter instance?