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

[Paul B Mahol]

On 8/28/20, Paul B Mahol <onemda at gmail.com> wrote:
> On 8/28/20, Paul B Mahol <onemda at gmail.com> wrote:
>> On 8/28/20, Andreas Rheinhardt <andreas.rheinhardt at gmail.com> wrote:
>>> 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?
>>>>
>>>
>>> I thought of a comment for demux_options like "Hint: The options are
>>> partially shared with the Wave64 demuxer."
>>
>> More like Warning instead of Hint.
>> So some other developer does not add option that does not make sense for
>> w64.
>
> Problem is demux_options are under ifdef so can not be shared as is.
> What about using macro to define max_size option or just keep it as in
> this patch.

Gonna apply with removed comma after {NULL} in w64 options.

>
>>
>>>
>>>>>
>>>>>> +
>>>>>> +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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>>>
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>