[FFmpeg-devel] [PATCH 2/3] avformat/mux: Avoid overhead of packet list in case of single streams

[James Almer]

On 10/9/2021 12:14 PM, Andreas Rheinhardt wrote:
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>   libavformat/internal.h |  7 +++++++
>   libavformat/mux.c      | 11 ++++++++++-
>   2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/libavformat/internal.h b/libavformat/internal.h
> index 223befdbc0..867b5de514 100644
> --- a/libavformat/internal.h
> +++ b/libavformat/internal.h
> @@ -760,6 +760,13 @@ int ff_add_attached_pic(AVFormatContext *s, AVStream *st, AVIOContext *pb,
>   int ff_interleave_packet_per_dts(AVFormatContext *s, AVPacket *pkt,
>                                    int flush, int has_packet);
>   
> +/**
> + * Interleave packets directly in the order in which they arrive
> + * without any sort of buffering.
> + */
> +int ff_interleave_packet_passthrough(AVFormatContext *s, AVPacket *pkt,
> +                                     int flush, int has_packet);
> +
>   void ff_free_stream(AVFormatContext *s, AVStream *st);
>   
>   unsigned int ff_codec_get_tag(const AVCodecTag *tags, enum AVCodecID id);
> diff --git a/libavformat/mux.c b/libavformat/mux.c
> index f4f1bc289e..a6129720dd 100644
> --- a/libavformat/mux.c
> +++ b/libavformat/mux.c
> @@ -334,7 +334,10 @@ static int init_muxer(AVFormatContext *s, AVDictionary **options)
>           if (par->codec_type != AVMEDIA_TYPE_ATTACHMENT)
>               si->nb_interleaved_streams++;
>       }
> -    si->interleave_packet = of->interleave_packet ? of->interleave_packet : ff_interleave_packet_per_dts;
> +    si->interleave_packet = of->interleave_packet ? of->interleave_packet :
> +                                si->nb_interleaved_streams > 1 ?
> +                                    ff_interleave_packet_per_dts :
> +                                    ff_interleave_packet_passthrough;

This is hard to read. Make it something like

si->interleave_packet = of->interleave_packet;
if (!si->interleave_packet)
     si->interleave_packet = si->nb_interleaved_streams > 1 ?
                                 ff_interleave_packet_per_dts :
                                 ff_interleave_packet_passthrough;

Instead, or at the very least add some brackets.

>   
>       if (!s->priv_data && of->priv_data_size > 0) {
>           s->priv_data = av_mallocz(of->priv_data_size);
> @@ -1026,6 +1029,12 @@ int ff_interleave_packet_per_dts(AVFormatContext *s, AVPacket *pkt,
>       }
>   }
>   
> +int ff_interleave_packet_passthrough(AVFormatContext *s, AVPacket *pkt,
> +                                     int flush, int has_packet)
> +{
> +    return has_packet;
> +}
> +
>   int ff_get_muxer_ts_offset(AVFormatContext *s, int stream_index, int64_t *offset)
>   {
>       AVStream *st;
>