Re: [FFmpeg-devel] [PATCH v5 1/2] avformat: refactor ff_stream_encode_params_copy() to ff_stream_params_copy()

[Pierre-Anthony Lemieux <pal@sandflow.com>]

On Thu, Aug 4, 2022 at 4:24 PM Pierre-Anthony Lemieux <pal@sandflow.com> wrote:
>
> On Thu, Aug 4, 2022 at 4:13 PM Andreas Rheinhardt
> <andreas.rheinhardt@outlook.com> wrote:
> >
> > Pierre-Anthony Lemieux:
> > > On Thu, Aug 4, 2022 at 3:22 PM Andreas Rheinhardt
> > > <andreas.rheinhardt@outlook.com> wrote:
> > >>
> > >> Pierre-Anthony Lemieux:
> > >>> On Thu, Aug 4, 2022 at 10:15 AM Andreas Rheinhardt
> > >>> <andreas.rheinhardt@outlook.com> wrote:
> > >>>>
> > >>>> Pierre-Anthony Lemieux:
> > >>>>> On Thu, Aug 4, 2022 at 9:53 AM Andreas Rheinhardt
> > >>>>> <andreas.rheinhardt@outlook.com> wrote:
> > >>>>>>
> > >>>>>> pal@sandflow.com:
> > >>>>>>> From: Pierre-Anthony Lemieux <pal@palemieux.com>
> > >>>>>>>
> > >>>>>>> As discussed at https://ffmpeg.org/pipermail/ffmpeg-devel/2022-July/298491.html.
> > >>>>>>> Note that ff_stream_params_copy() does not copy:
> > >>>>>>>  * the index field
> > >>>>>>>  * the attached_pic if its size is 0
> > >>>>>>>
> > >>>>>>> Addresses http://ffmpeg.org/pipermail/ffmpeg-devel/2022-August/299514.html
> > >>>>>>>
> > >>>>>>> ---
> > >>>>>>>  libavformat/avformat.c   | 40 ++++++++++++++++++++++++++++++++++++++++
> > >>>>>>>  libavformat/fifo.c       |  2 +-
> > >>>>>>>  libavformat/internal.h   | 12 ++++++++++++
> > >>>>>>>  libavformat/mux.h        |  9 ---------
> > >>>>>>>  libavformat/mux_utils.c  | 28 ----------------------------
> > >>>>>>>  libavformat/segment.c    |  2 +-
> > >>>>>>>  libavformat/tee.c        |  2 +-
> > >>>>>>>  libavformat/webm_chunk.c |  2 +-
> > >>>>>>>  8 files changed, 56 insertions(+), 41 deletions(-)
> > >>>>>>>
> > >>>>>>> diff --git a/libavformat/avformat.c b/libavformat/avformat.c
> > >>>>>>> index 30d6ea6a49..242187c359 100644
> > >>>>>>> --- a/libavformat/avformat.c
> > >>>>>>> +++ b/libavformat/avformat.c
> > >>>>>>> @@ -235,6 +235,46 @@ int ff_stream_side_data_copy(AVStream *dst, const AVStream *src)
> > >>>>>>>      return 0;
> > >>>>>>>  }
> > >>>>>>>
> > >>>>>>> +int ff_stream_params_copy(AVStream *dst, const AVStream *src)
> > >>>>>>> +{
> > >>>>>>> +    int ret;
> > >>>>>>> +
> > >>>>>>> +    dst->id                  = src->id;
> > >>>>>>> +    dst->time_base           = src->time_base;
> > >>>>>>> +    dst->start_time          = src->start_time;
> > >>>>>>> +    dst->duration            = src->duration;
> > >>>>>>> +    dst->nb_frames           = src->nb_frames;
> > >>>>>>> +    dst->disposition         = src->disposition;
> > >>>>>>> +    dst->discard             = src->discard;
> > >>>>>>> +    dst->sample_aspect_ratio = src->sample_aspect_ratio;
> > >>>>>>> +    dst->avg_frame_rate      = src->avg_frame_rate;
> > >>>>>>> +    dst->event_flags         = src->event_flags;
> > >>>>>>> +    dst->r_frame_rate        = src->r_frame_rate;
> > >>>>>>> +    dst->pts_wrap_bits       = src->pts_wrap_bits;
> > >>>>>>> +
> > >>>>>>> +    av_dict_free(&dst->metadata);
> > >>>>>>> +    ret = av_dict_copy(&dst->metadata, src->metadata, 0);
> > >>>>>>> +    if (ret < 0)
> > >>>>>>> +        return ret;
> > >>>>>>> +
> > >>>>>>> +    ret = avcodec_parameters_copy(dst->codecpar, src->codecpar);
> > >>>>>>> +    if (ret < 0)
> > >>>>>>> +        return ret;
> > >>>>>>> +
> > >>>>>>> +    ret = ff_stream_side_data_copy(dst, src);
> > >>>>>>> +    if (ret < 0)
> > >>>>>>> +        return ret;
> > >>>>>>> +
> > >>>>>>> +    av_packet_unref(&dst->attached_pic);
> > >>>>>>> +    if (src->attached_pic.size > 0) {
> > >>>>>>> +        ret = av_packet_ref(&dst->attached_pic, &src->attached_pic);
> > >>>>>>> +        if (ret < 0)
> > >>>>>>> +            return ret;
> > >>>>>>> +    }
> > >>>>>>> +
> > >>>>>>> +    return 0;
> > >>>>>>> +}
> > >>>>>>> +
> > >>>>>>>  AVProgram *av_new_program(AVFormatContext *ac, int id)
> > >>>>>>>  {
> > >>>>>>>      AVProgram *program = NULL;
> > >>>>>>> diff --git a/libavformat/fifo.c b/libavformat/fifo.c
> > >>>>>>> index ead2bdc5cf..fef116d040 100644
> > >>>>>>> --- a/libavformat/fifo.c
> > >>>>>>> +++ b/libavformat/fifo.c
> > >>>>>>> @@ -509,7 +509,7 @@ static int fifo_mux_init(AVFormatContext *avf, const AVOutputFormat *oformat,
> > >>>>>>>          if (!st)
> > >>>>>>>              return AVERROR(ENOMEM);
> > >>>>>>>
> > >>>>>>> -        ret = ff_stream_encode_params_copy(st, avf->streams[i]);
> > >>>>>>> +        ret = ff_stream_params_copy(st, avf->streams[i]);
> > >>>>>>>          if (ret < 0)
> > >>>>>>>              return ret;
> > >>>>>>>      }
> > >>>>>>> diff --git a/libavformat/internal.h b/libavformat/internal.h
> > >>>>>>> index b6b8fbf56f..87a00bbae3 100644
> > >>>>>>> --- a/libavformat/internal.h
> > >>>>>>> +++ b/libavformat/internal.h
> > >>>>>>> @@ -625,6 +625,18 @@ enum AVCodecID ff_get_pcm_codec_id(int bps, int flt, int be, int sflags);
> > >>>>>>>   */
> > >>>>>>>  int ff_stream_side_data_copy(AVStream *dst, const AVStream *src);
> > >>>>>>>
> > >>>>>>> +/**
> > >>>>>>> + * Copy all stream parameters from source to destination stream, with the
> > >>>>>>> + * exception of:
> > >>>>>>> + *  * the index field, which is usually set by avformat_new_stream()
> > >>>>>>> + *  * the attached_pic field, if attached_pic.size is 0 or less
> > >>>>>>> + *
> > >>>>>>> + * @param dst pointer to destination AVStream
> > >>>>>>> + * @param src pointer to source AVStream
> > >>>>>>> + * @return >=0 on success, AVERROR code on error
> > >>>>>>> + */
> > >>>>>>> +int ff_stream_params_copy(AVStream *dst, const AVStream *src);
> > >>>>>>> +
> > >>>>>>>  /**
> > >>>>>>>   * Wrap ffurl_move() and log if error happens.
> > >>>>>>>   *
> > >>>>>>> diff --git a/libavformat/mux.h b/libavformat/mux.h
> > >>>>>>> index c01da82194..1bfcaf795f 100644
> > >>>>>>> --- a/libavformat/mux.h
> > >>>>>>> +++ b/libavformat/mux.h
> > >>>>>>> @@ -113,15 +113,6 @@ int ff_format_shift_data(AVFormatContext *s, int64_t read_start, int shift_size)
> > >>>>>>>   */
> > >>>>>>>  int ff_format_output_open(AVFormatContext *s, const char *url, AVDictionary **options);
> > >>>>>>>
> > >>>>>>> -/**
> > >>>>>>> - * Copy encoding parameters from source to destination stream
> > >>>>>>> - *
> > >>>>>>> - * @param dst pointer to destination AVStream
> > >>>>>>> - * @param src pointer to source AVStream
> > >>>>>>> - * @return >=0 on success, AVERROR code on error
> > >>>>>>> - */
> > >>>>>>> -int ff_stream_encode_params_copy(AVStream *dst, const AVStream *src);
> > >>>>>>> -
> > >>>>>>>  /**
> > >>>>>>>   * Parse creation_time in AVFormatContext metadata if exists and warn if the
> > >>>>>>>   * parsing fails.
> > >>>>>>> diff --git a/libavformat/mux_utils.c b/libavformat/mux_utils.c
> > >>>>>>> index eb8ea3d560..2fa2ab5b0f 100644
> > >>>>>>> --- a/libavformat/mux_utils.c
> > >>>>>>> +++ b/libavformat/mux_utils.c
> > >>>>>>> @@ -121,34 +121,6 @@ int ff_format_output_open(AVFormatContext *s, const char *url, AVDictionary **op
> > >>>>>>>      return 0;
> > >>>>>>>  }
> > >>>>>>>
> > >>>>>>> -int ff_stream_encode_params_copy(AVStream *dst, const AVStream *src)
> > >>>>>>> -{
> > >>>>>>> -    int ret;
> > >>>>>>> -
> > >>>>>>> -    dst->id                  = src->id;
> > >>>>>>> -    dst->time_base           = src->time_base;
> > >>>>>>> -    dst->nb_frames           = src->nb_frames;
> > >>>>>>> -    dst->disposition         = src->disposition;
> > >>>>>>> -    dst->sample_aspect_ratio = src->sample_aspect_ratio;
> > >>>>>>> -    dst->avg_frame_rate      = src->avg_frame_rate;
> > >>>>>>> -    dst->r_frame_rate        = src->r_frame_rate;
> > >>>>>>> -
> > >>>>>>> -    av_dict_free(&dst->metadata);
> > >>>>>>> -    ret = av_dict_copy(&dst->metadata, src->metadata, 0);
> > >>>>>>> -    if (ret < 0)
> > >>>>>>> -        return ret;
> > >>>>>>> -
> > >>>>>>> -    ret = avcodec_parameters_copy(dst->codecpar, src->codecpar);
> > >>>>>>> -    if (ret < 0)
> > >>>>>>> -        return ret;
> > >>>>>>> -
> > >>>>>>> -    ret = ff_stream_side_data_copy(dst, src);
> > >>>>>>> -    if (ret < 0)
> > >>>>>>> -        return ret;
> > >>>>>>> -
> > >>>>>>> -    return 0;
> > >>>>>>> -}
> > >>>>>>> -
> > >>>>>>>  int ff_parse_creation_time_metadata(AVFormatContext *s, int64_t *timestamp, int return_seconds)
> > >>>>>>>  {
> > >>>>>>>      AVDictionaryEntry *entry;
> > >>>>>>> diff --git a/libavformat/segment.c b/libavformat/segment.c
> > >>>>>>> index fa435d9f32..a8f3e94714 100644
> > >>>>>>> --- a/libavformat/segment.c
> > >>>>>>> +++ b/libavformat/segment.c
> > >>>>>>> @@ -169,7 +169,7 @@ static int segment_mux_init(AVFormatContext *s)
> > >>>>>>>
> > >>>>>>>          if (!(st = avformat_new_stream(oc, NULL)))
> > >>>>>>>              return AVERROR(ENOMEM);
> > >>>>>>> -        ret = ff_stream_encode_params_copy(st, ist);
> > >>>>>>> +        ret = ff_stream_params_copy(st, ist);
> > >>>>>>>          if (ret < 0)
> > >>>>>>>              return ret;
> > >>>>>>>          opar = st->codecpar;
> > >>>>>>> diff --git a/libavformat/tee.c b/libavformat/tee.c
> > >>>>>>> index f1f2a9d2a5..dbfad604d0 100644
> > >>>>>>> --- a/libavformat/tee.c
> > >>>>>>> +++ b/libavformat/tee.c
> > >>>>>>> @@ -289,7 +289,7 @@ static int open_slave(AVFormatContext *avf, char *slave, TeeSlave *tee_slave)
> > >>>>>>>              goto end;
> > >>>>>>>          }
> > >>>>>>>
> > >>>>>>> -        ret = ff_stream_encode_params_copy(st2, st);
> > >>>>>>> +        ret = ff_stream_params_copy(st2, st);
> > >>>>>>>          if (ret < 0)
> > >>>>>>>              goto end;
> > >>>>>>>      }
> > >>>>>>> diff --git a/libavformat/webm_chunk.c b/libavformat/webm_chunk.c
> > >>>>>>> index d69db3a004..39f21fce7a 100644
> > >>>>>>> --- a/libavformat/webm_chunk.c
> > >>>>>>> +++ b/libavformat/webm_chunk.c
> > >>>>>>> @@ -94,7 +94,7 @@ static int webm_chunk_init(AVFormatContext *s)
> > >>>>>>>      if (!(st = avformat_new_stream(oc, NULL)))
> > >>>>>>>          return AVERROR(ENOMEM);
> > >>>>>>>
> > >>>>>>> -    if ((ret = ff_stream_encode_params_copy(st, ost)) < 0)
> > >>>>>>> +    if ((ret = ff_stream_params_copy(st, ost)) < 0)
> > >>>>>>>          return ret;
> > >>>>>>>
> > >>>>>>>      if (wc->http_method)
> > >>>>>>
> > >>>>>> Looking at these callers shows that they all have one thing in common:
> > >>>>>> They create a stream and immediately afterwards copy stream parameters.
> > >>>>>> The caller that you intend to add in #2 does the same. How about we make
> > >>>>>> a function that is equivalent to
> > >>>>>> avformat_new_stream+ff_stream_params_copy above and use that? (But
> > >>>>>> please leave ff_stream_params_copy as it is in the form of a static
> > >>>>>> function.)
> > >>>>>
> > >>>>> avformat_clone_stream()?
> > >>>>>
> > >>>>
> > >>>> I was not thinking about a public function. But clone_stream sounds good.
> > >>>
> > >>> Something like this?
> > >>>
> > >>> int ff_stream_clone(AVFormatContext *s, AVStream **dst, const AVStream *src)
> > >>> {
> > >>>     AVStream *st;
> > >>>     int ret;
> > >>>
> > >>>     st = avformat_new_stream(s, NULL);
> > >>>     if (!st)
> > >>>         return AVERROR(ENOMEM);
> > >>>
> > >>>     ret = stream_params_copy(st, src);
> > >>>     if (ret < 0)
> > >>>         return ret;
> > >>>
> > >>>     *dst = st;
> > >>>
> > >>>     return 0;
> > >>> }
> > >>>
> > >>
> > >> I'd use AVStream *ff_stream_clone(AVFormatContext *dst_ctx, const
> > >> AVStream *src);
> > >
> > > How does one recover a pointer to the stream that was just created?
> > > Isn't there a potential race condition with dst_ctx[nb_streams - 1]?
> > >
> >
> > ?
> > 1. The function is supposed to return the stream just created; just like
> > avformat_new_stream does.
>
> Oh. I missed the return of AVStream*.
>
> We lose the error code returned by stream_params_copy(). Works for me though.

Addressed at v6.

>
> > 2. If there are multiple threads adding streams to dst_ctx, we'd already
> > be screwed anyway (avformat_new_stream does not use any lock).
> >
> > - Andreas
> > _______________________________________________
> > ffmpeg-devel mailing list
> > ffmpeg-devel@ffmpeg.org
> > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> >
> > To unsubscribe, visit link above, or email
> > ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".
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