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 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;
}

>
> - Andreas
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