[FFmpeg-devel] [PATCH] avformat/wavdec: allow to change max size of single demuxed packet

[Andreas Rheinhardt]

Paul B Mahol:
> Can make demuxing much faster, expecially for files with
> huge number of channels.
> 
> Signed-off-by: Paul B Mahol <onemda at gmail.com>
> ---
>  libavformat/wavdec.c | 21 ++++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/wavdec.c b/libavformat/wavdec.c
> index e1b2115434..5b3c481421 100644
> --- a/libavformat/wavdec.c
> +++ b/libavformat/wavdec.c
> @@ -56,6 +56,7 @@ typedef struct WAVDemuxContext {
>      int smv_eof;
>      int audio_eof;
>      int ignore_length;
> +    int max_size;
>      int spdif;
>      int smv_cur_pt;
>      int smv_given_first;
> @@ -628,8 +629,6 @@ static int64_t find_guid(AVIOContext *pb, const uint8_t guid1[16])
>      return AVERROR_EOF;
>  }
>  
> -#define MAX_SIZE 4096
> -
>  static int wav_read_packet(AVFormatContext *s, AVPacket *pkt)
>  {
>      int ret, size;
> @@ -706,7 +705,7 @@ smv_out:
>          wav->data_end = avio_tell(s->pb) + left;
>      }
>  
> -    size = MAX_SIZE;
> +    size = wav->max_size;
>      if (st->codecpar->block_align > 1) {
>          if (size < st->codecpar->block_align)
>              size = st->codecpar->block_align;
> @@ -759,6 +758,7 @@ static int wav_read_seek(AVFormatContext *s,
>  #define DEC AV_OPT_FLAG_DECODING_PARAM
>  static const AVOption demux_options[] = {
>      { "ignore_length", "Ignore length", OFFSET(ignore_length), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, DEC },
> +    { "max_size",      "max size of single packet", OFFSET(max_size), AV_OPT_TYPE_INT, { .i64 = 4096 }, 1024, 1 << 22, DEC },
>      { NULL },
>  };
>  
> @@ -906,6 +906,20 @@ static int w64_read_header(AVFormatContext *s)
>      return 0;
>  }
>  
> +#define OFFSET(x) offsetof(WAVDemuxContext, x)
> +#define DEC AV_OPT_FLAG_DECODING_PARAM
> +static const AVOption w64_demux_options[] = {
> +    { "max_size", "max size of single packet", OFFSET(max_size), AV_OPT_TYPE_INT, { .i64 = 4096 }, 1024, 1 << 22, DEC },
> +    { NULL },

The ',' is unnecessary: Nothing will ever be added after the sentinel.

> +};

You can use &demux_options[1] instead of w64_demux_options (but add a
comment for this).

> +
> +static const AVClass w64_demuxer_class = {
> +    .class_name = "W64 demuxer",
> +    .item_name  = av_default_item_name,
> +    .option     = w64_demux_options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
>  AVInputFormat ff_w64_demuxer = {
>      .name           = "w64",
>      .long_name      = NULL_IF_CONFIG_SMALL("Sony Wave64"),
> @@ -916,5 +930,6 @@ AVInputFormat ff_w64_demuxer = {
>      .read_seek      = wav_read_seek,
>      .flags          = AVFMT_GENERIC_INDEX,
>      .codec_tag      = (const AVCodecTag * const []) { ff_codec_wav_tags, 0 },
> +    .priv_class     = &w64_demuxer_class,
>  };
>  #endif /* CONFIG_W64_DEMUXER */
>