[FFmpeg-devel] [PATCH] fftools/ffmpeg: make specifying thread_queue_size turn on threaded input

[Marton Balint]

On Sat, 18 Jul 2020, Marton Balint wrote:

> Threaded input can increase smoothness of e.g. x11grab significantly. Before
> this patch, in order to activate threaded input the user had to specify a
> "dummy" additional input, with this change it is no longer required.

Ping, will apply soon.

Regards,
Marton

>
> Signed-off-by: Marton Balint <cus at passwd.hu>
> ---
> doc/ffmpeg.texi      | 5 +++--
> fftools/ffmpeg.c     | 6 ++++--
> fftools/ffmpeg_opt.c | 3 ++-
> 3 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> index 70b8965d7f..267ddfe8b5 100644
> --- a/doc/ffmpeg.texi
> +++ b/doc/ffmpeg.texi
> @@ -1689,8 +1689,9 @@ not start from timestamp 0, such as transport streams.
> @item -thread_queue_size @var{size} (@emph{input})
> This option sets the maximum number of queued packets when reading from the
> file or device. With low latency / high rate live streams, packets may be
> -discarded if they are not read in a timely manner; raising this value can
> -avoid it.
> +discarded if they are not read in a timely manner; setting this value can
> +force ffmpeg to use a separate input thread and read packets as soon as they
> +arrive. By default ffmpeg only do this if multiple inputs are specified.
> 
> @item -sdp_file @var{file} (@emph{global})
> Print sdp information for an output stream to @var{file}.
> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> index 2e9448ea2b..173ac3c9a0 100644
> --- a/fftools/ffmpeg.c
> +++ b/fftools/ffmpeg.c
> @@ -4051,7 +4051,9 @@ static int init_input_thread(int i)
>     int ret;
>     InputFile *f = input_files[i];
> 
> -    if (nb_input_files == 1)
> +    if (f->thread_queue_size < 0)
> +        f->thread_queue_size = (nb_input_files > 1 ? 8 : 0);
> +    if (!f->thread_queue_size)
>         return 0;
>
>     if (f->ctx->pb ? !f->ctx->pb->seekable :
> @@ -4105,7 +4107,7 @@ static int get_input_packet(InputFile *f, AVPacket *pkt)
>     }
> 
> #if HAVE_THREADS
> -    if (nb_input_files > 1)
> +    if (f->thread_queue_size)
>         return get_input_packet_mt(f, pkt);
> #endif
>     return av_read_frame(f->ctx, pkt);
> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> index 9d1489ce01..853550a142 100644
> --- a/fftools/ffmpeg_opt.c
> +++ b/fftools/ffmpeg_opt.c
> @@ -228,6 +228,7 @@ static void init_options(OptionsContext *o)
>     o->limit_filesize = UINT64_MAX;
>     o->chapters_input_file = INT_MAX;
>     o->accurate_seek  = 1;
> +    o->thread_queue_size = -1;
> }
> 
> static int show_hwaccels(void *optctx, const char *opt, const char *arg)
> @@ -1270,7 +1271,7 @@ static int open_input_file(OptionsContext *o, const char *filename)
>     f->duration = 0;
>     f->time_base = (AVRational){ 1, 1 };
> #if HAVE_THREADS
> -    f->thread_queue_size = o->thread_queue_size > 0 ? o->thread_queue_size : 8;
> +    f->thread_queue_size = o->thread_queue_size;
> #endif
>
>     /* check if all codec options have been used */
> -- 
> 2.26.2
>
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