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

[Paul B Mahol]

On 8/28/20, Andreas Rheinhardt <andreas.rheinhardt at gmail.com> wrote:
> 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).

How the comment should look like?

>
>> +
>> +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 */
>>
>
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