[FFmpeg-devel] [PATCH] doc/examples/remuxing: switch to codecpar

[Matthieu Bouron]

On Tue, Mar 28, 2017 at 12:48 PM, wm4 <nfxjfg at googlemail.com> wrote:

> On Tue, 28 Mar 2017 12:32:19 +0200
> Matthieu Bouron <matthieu.bouron at gmail.com> wrote:
>
> > Also limits remuxing to audio, video and subtitle streams.
> > ---
> >  doc/examples/remuxing.c | 48 ++++++++++++++++++++++++++++++
> +++++++++++-------
> >  1 file changed, 41 insertions(+), 7 deletions(-)
> >
> > diff --git a/doc/examples/remuxing.c b/doc/examples/remuxing.c
> > index 65437d9abd..8615c73842 100644
> > --- a/doc/examples/remuxing.c
> > +++ b/doc/examples/remuxing.c
> > @@ -50,6 +50,9 @@ int main(int argc, char **argv)
> >      AVPacket pkt;
> >      const char *in_filename, *out_filename;
> >      int ret, i;
> > +    int stream_index = 0;
> > +    int *stream_mapping = NULL;
> > +    int stream_mapping_size = 0;
> >
> >      if (argc < 3) {
> >          printf("usage: %s input output\n"
> > @@ -83,25 +86,48 @@ int main(int argc, char **argv)
> >          goto end;
> >      }
> >
> > +    stream_mapping_size = ifmt_ctx->nb_streams;
> > +    stream_mapping = av_mallocz_array(stream_mapping_size,
> sizeof(*stream_mapping));
> > +    if (!stream_mapping) {
> > +        ret = AVERROR(ENOMEM);
> > +        goto end;
> > +    }
> > +
> >      ofmt = ofmt_ctx->oformat;
> >
> >      for (i = 0; i < ifmt_ctx->nb_streams; i++) {
> > +        AVStream *out_stream;
> >          AVStream *in_stream = ifmt_ctx->streams[i];
> > -        AVStream *out_stream = avformat_new_stream(ofmt_ctx,
> in_stream->codec->codec);
> > +        AVCodecParameters *in_codecpar = in_stream->codecpar;
> > +
> > +        if (in_codecpar->codec_type != AVMEDIA_TYPE_AUDIO &&
> > +            in_codecpar->codec_type != AVMEDIA_TYPE_VIDEO &&
> > +            in_codecpar->codec_type != AVMEDIA_TYPE_SUBTITLE) {
> > +            stream_mapping[i] = -1;
> > +            continue;
> > +        }
> > +
> > +        stream_mapping[i] = stream_index++;
> > +
> > +        out_stream = avformat_new_stream(ofmt_ctx, NULL);
> >          if (!out_stream) {
> >              fprintf(stderr, "Failed allocating output stream\n");
> >              ret = AVERROR_UNKNOWN;
> >              goto end;
> >          }
> >
> > -        ret = avcodec_copy_context(out_stream->codec,
> in_stream->codec);
> > +        ret = avcodec_parameters_copy(out_stream->codecpar,
> in_codecpar);
> >          if (ret < 0) {
> > -            fprintf(stderr, "Failed to copy context from input to
> output stream codec context\n");
> > +            fprintf(stderr, "Failed to copy copy codec parameters\n");
> > +            goto end;
> > +        }
> > +        out_stream->codecpar->codec_tag = 0;
> > +
> > +        ret = avformat_transfer_internal_stream_timing_info(ofmt,
> out_stream, in_stream, AVFMT_TBCF_AUTO);
> > +        if (ret < 0) {
> > +            fprintf(stderr, "Failed to copy stream timing info\n");
>
> Remove this call. It was made for obscure corner cases like ffserver,
> and one avi thing AFAIK?
>
>

I just ran fate with ffmpeg.c compiled without the
avformat_transfer_internal_stream_timing_info call, and it broke in many
areas.

On the other hand, it only seems to transfer ist->time_base to
enc_ctx->time_base for the general case, which shouldn't be useful for
remuxing (i can be missing things though). I removed the call locally.

>              goto end;
> >          }
> > -        out_stream->codec->codec_tag = 0;
> > -        if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
> > -            out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
> >      }
> >      av_dump_format(ofmt_ctx, 0, out_filename, 1);
> >
> > @@ -127,8 +153,14 @@ int main(int argc, char **argv)
> >              break;
> >
> >          in_stream  = ifmt_ctx->streams[pkt.stream_index];
> > -        out_stream = ofmt_ctx->streams[pkt.stream_index];
> > +        if (pkt.stream_index >= stream_mapping_size ||
> > +            stream_mapping[pkt.stream_index] < 0) {
> > +            av_packet_unref(&pkt);
> > +            continue;
> > +        }
> >
> > +        pkt.stream_index = stream_mapping[pkt.stream_index];
> > +        out_stream = ofmt_ctx->streams[pkt.stream_index];
> >          log_packet(ifmt_ctx, &pkt, "in");
> >
> >          /* copy packet */
> > @@ -156,6 +188,8 @@ end:
> >          avio_closep(&ofmt_ctx->pb);
> >      avformat_free_context(ofmt_ctx);
> >
> > +    av_freep(&stream_mapping);
> > +
> >      if (ret < 0 && ret != AVERROR_EOF) {
> >          fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
> >          return 1;
>
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