[FFmpeg-devel] [PATCH 1/1] avformat/mpegenc.c: vbvsize option

[Michael Niedermayer]

On Thu, Oct 31, 2019 at 06:04:58PM +0100, Nicolas Gaullier wrote:
> Allow the user to set or override the vbv size
> ---
>  libavformat/mpegenc.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/mpegenc.c b/libavformat/mpegenc.c
> index f6980231a2..1613c8afa1 100644
> --- a/libavformat/mpegenc.c
> +++ b/libavformat/mpegenc.c
> @@ -67,6 +67,7 @@ typedef struct MpegMuxContext {
>      int system_header_freq;
>      int system_header_size;
>      int user_mux_rate; /* bitrate in units of bits/s */
> +    int user_vbv_size; /* vbv buffer size in units of bits/s */
>      int mux_rate; /* bitrate in units of 50 bytes/s */
>      /* stream info */
>      int audio_bound;
> @@ -433,7 +434,9 @@ static av_cold int mpeg_mux_init(AVFormatContext *ctx)
>                  stream->id = mpv_id++;
>  
>              props = (AVCPBProperties*)av_stream_get_side_data(st, AV_PKT_DATA_CPB_PROPERTIES, NULL);
> -            if (props && props->buffer_size)
> +            if (s->user_vbv_size)
> +                stream->max_buffer_size = 6 * 1024 + s->user_vbv_size / 8;
> +            else if (props && props->buffer_size)
>                  stream->max_buffer_size = 6 * 1024 + props->buffer_size / 8;
>              else {
>                  av_log(ctx, AV_LOG_WARNING,
> @@ -1268,6 +1271,7 @@ static void mpeg_mux_deinit(AVFormatContext *ctx)
>  #define E AV_OPT_FLAG_ENCODING_PARAM
>  static const AVOption options[] = {
>      { "muxrate", NULL,                                          OFFSET(user_mux_rate), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, ((1<<22) - 1) * (8 * 50), E },
> +    { "vbvsize", "set vbv buffer size (in bits)",               OFFSET(user_vbv_size), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, (1LL<<32) - 1, E},
>      { "preload", "Initial demux-decode delay in microseconds.", OFFSET(preload),  AV_OPT_TYPE_INT, { .i64 = 500000 }, 0, INT_MAX, E },
>      { NULL },
>  };

This is not the "correct" way to handle this, because one mpeg container
can contain many streams and this is just one parameter for the container.
while the vbvsize is a parameter per stream.

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In a rich man's house there is no place to spit but his face.
-- Diogenes of Sinope
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