Re: [FFmpeg-devel] [PATCH v3 1/3] lavf/dashdec: Prepare DASH decoder for multithreading

[Steven Liu <lingjiujianke@gmail.com>]

Lukas Fellechner <lukas.fellechner@gmx.net> 于2022年8月24日周三 03:04写道：
>
> For adding multithreading to the DASH decoder initialization,
> the open_demux_for_component() method must be split up into two parts:
>
> begin_open_demux_for_component(): Opens the stream and does probing
> and format detection. This can be run in parallel.
>
> end_open_demux_for_component(): Creates the AVStreams and adds
> them to the common parent AVFormatContext. This method must always be
> run synchronously, after all threads are finished.
> ---
>  libavformat/dashdec.c | 42 ++++++++++++++++++++++++++++++------------
>  1 file changed, 30 insertions(+), 12 deletions(-)
>
> diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
> index 63bf7e96a5..e82da45e43 100644
> --- a/libavformat/dashdec.c
> +++ b/libavformat/dashdec.c
> @@ -1918,10 +1918,9 @@ fail:
>      return ret;
>  }
>
> -static int open_demux_for_component(AVFormatContext *s, struct representation *pls)
> +static int begin_open_demux_for_component(AVFormatContext *s, struct representation *pls)
>  {
>      int ret = 0;
> -    int i;
>
>      pls->parent = s;
>      pls->cur_seq_no  = calc_cur_seg_no(s, pls);
> @@ -1931,9 +1930,15 @@ static int open_demux_for_component(AVFormatContext *s, struct representation *p
>      }
>
>      ret = reopen_demux_for_component(s, pls);
> -    if (ret < 0) {
> -        goto fail;
> -    }
> +
> +    return ret;
> +}
> +
> +static int end_open_demux_for_component(AVFormatContext *s, struct representation *pls)
> +{
> +    int ret = 0;
> +    int i;
> +
>      for (i = 0; i < pls->ctx->nb_streams; i++) {
>          AVStream *st = avformat_new_stream(s, NULL);
>          AVStream *ist = pls->ctx->streams[i];
> @@ -1965,6 +1970,19 @@ fail:
>      return ret;
>  }
>
> +static int open_demux_for_component(AVFormatContext* s, struct representation* pls)
> +{
> +    int ret = 0;
> +
> +    ret = begin_open_demux_for_component(s, pls);
> +    if (ret < 0)
> +        return ret;
> +
> +    ret = end_open_demux_for_component(s, pls);
> +
> +    return ret;
> +}
> +
>  static int is_common_init_section_exist(struct representation **pls, int n_pls)
>  {
>      struct fragment *first_init_section = pls[0]->init_section;
> @@ -2040,9 +2058,15 @@ static int dash_read_header(AVFormatContext *s)
>          av_dict_set(&c->avio_opts, "seekable", "0", 0);
>      }
>
> -    if(c->n_videos)
> +    if (c->n_videos)
>          c->is_init_section_common_video = is_common_init_section_exist(c->videos, c->n_videos);
>
> +    if (c->n_audios)
> +        c->is_init_section_common_audio = is_common_init_section_exist(c->audios, c->n_audios);
> +
> +    if (c->n_subtitles)
> +        c->is_init_section_common_subtitle = is_common_init_section_exist(c->subtitles, c->n_subtitles);
> +
>      /* Open the demuxer for video and audio components if available */
>      for (i = 0; i < c->n_videos; i++) {
>          rep = c->videos[i];
> @@ -2059,9 +2083,6 @@ static int dash_read_header(AVFormatContext *s)
>          ++stream_index;
>      }
>
> -    if(c->n_audios)
> -        c->is_init_section_common_audio = is_common_init_section_exist(c->audios, c->n_audios);
> -
>      for (i = 0; i < c->n_audios; i++) {
>          rep = c->audios[i];
>          if (i > 0 && c->is_init_section_common_audio) {
> @@ -2077,9 +2098,6 @@ static int dash_read_header(AVFormatContext *s)
>          ++stream_index;
>      }
>
> -    if (c->n_subtitles)
> -        c->is_init_section_common_subtitle = is_common_init_section_exist(c->subtitles, c->n_subtitles);
> -
>      for (i = 0; i < c->n_subtitles; i++) {
>          rep = c->subtitles[i];
>          if (i > 0 && c->is_init_section_common_subtitle) {
> --
> 2.31.1.windows.1
>
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Patchset looks ok and test passed here. Any comments?


Thanks
Steven
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