Re: [FFmpeg-devel] [PATCH] avformat/pcmdec: add pts and dts calculation for pcmdec

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

Hiccup Zhu:
> The purpose of this patch is to calculate pts and dts when using pcmdemux.
> Is there anything wrong with doing this, or do you have any suggestions for
> improvement?
> 

1. Don't top-post on this list.
2. PTS and DTS are already produced with this demuxer. As has been said:
If it isn't for you, open a ticket about it.

> Andreas Rheinhardt <andreas.rheinhardt@outlook.com> 于2024年5月14日周二 19:41写道：
> 
>> Shiqi Zhu:
>>> Signed-off-by: Shiqi Zhu <hiccupzhu@gmail.com>
>>> ---
>>>  libavformat/pcmdec.c | 37 +++++++++++++++++++++++++++++++++++--
>>>  1 file changed, 35 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/libavformat/pcmdec.c b/libavformat/pcmdec.c
>>> index 2f6508b75a..d879aefaad 100644
>>> --- a/libavformat/pcmdec.c
>>> +++ b/libavformat/pcmdec.c
>>> @@ -36,6 +36,7 @@ typedef struct PCMAudioDemuxerContext {
>>>      AVClass *class;
>>>      int sample_rate;
>>>      AVChannelLayout ch_layout;
>>> +    int64_t nb_samples;
>>>  } PCMAudioDemuxerContext;
>>>
>>>  static int pcm_read_header(AVFormatContext *s)
>>> @@ -46,6 +47,7 @@ static int pcm_read_header(AVFormatContext *s)
>>>      uint8_t *mime_type = NULL;
>>>      int ret;
>>>
>>> +    s1->nb_samples = 0;
>>>      st = avformat_new_stream(s, NULL);
>>>      if (!st)
>>>          return AVERROR(ENOMEM);
>>> @@ -104,6 +106,37 @@ static int pcm_read_header(AVFormatContext *s)
>>>      return 0;
>>>  }
>>>
>>> +static int pcm_dec_read_packet(AVFormatContext *s, AVPacket *pkt)
>>> +{
>>> +    PCMAudioDemuxerContext *s1 = s->priv_data;
>>> +    AVCodecParameters *par = s->streams[0]->codecpar;
>>> +    int ret;
>>> +
>>> +    ret = ff_pcm_read_packet(s, pkt);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    pkt->time_base = s->streams[0]->time_base;
>>> +    pkt->dts = pkt->pts = s1->nb_samples;
>>> +    s1->nb_samples += pkt->size / par->block_align;
>>> +
>>> +    return ret;
>>> +}
>>> +
>>> +static int pcm_dec_read_seek(AVFormatContext *s,
>>> +                             int stream_index, int64_t timestamp, int
>> flags)
>>> +{
>>> +    PCMAudioDemuxerContext *s1 = s->priv_data;
>>> +    int ret;
>>> +
>>> +    ret = ff_pcm_read_seek(s, stream_index, timestamp, flags);
>>> +    if (ret < 0)
>>> +        return ret;
>>> +
>>> +    s1->nb_samples = ffstream(s->streams[0])->cur_dts;
>>> +    return ret;
>>> +}
>>> +
>>>  static const AVOption pcm_options[] = {
>>>      { "sample_rate", "", offsetof(PCMAudioDemuxerContext, sample_rate),
>> AV_OPT_TYPE_INT, {.i64 = 44100}, 0, INT_MAX, AV_OPT_FLAG_DECODING_PARAM },
>>>      { "ch_layout",   "", offsetof(PCMAudioDemuxerContext, ch_layout),
>>  AV_OPT_TYPE_CHLAYOUT, {.str = "mono"}, 0, 0, AV_OPT_FLAG_DECODING_PARAM },
>>> @@ -126,8 +159,8 @@ const FFInputFormat ff_pcm_ ## name_ ## _demuxer =
>> {        \
>>>      .p.priv_class   = &pcm_demuxer_class,                   \
>>>      .priv_data_size = sizeof(PCMAudioDemuxerContext),       \
>>>      .read_header    = pcm_read_header,                      \
>>> -    .read_packet    = ff_pcm_read_packet,                   \
>>> -    .read_seek      = ff_pcm_read_seek,                     \
>>> +    .read_packet    = pcm_dec_read_packet,                  \
>>> +    .read_seek      = pcm_dec_read_seek,                    \
>>>      .raw_codec_id   = codec,                                \
>>>      __VA_ARGS__                                             \
>>>  };
>>
>> A quick test shows that PTS and DTS are already set generically for pcm
>> formats (unless the AVFMT_FLAG_NOFILLIN flag is set). If it is not in
>> your usecase, then you should provide details about this (preferably by
>> opening a ticket on trac).
>>
>> - Andreas
>>
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>>
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>>
> 
> 

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