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

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

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.
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".