[FFmpeg-devel] [PATCH 2/2] lavd/lavfi: allow to extract subcc.

anshul anshul.ffmpeg at gmail.com
Thu Mar 13 09:22:33 CET 2014


On 03/10/2014 04:26 PM, Nicolas George wrote:
> Signed-off-by: Nicolas George <george at nsup.org>
> ---
>   doc/indevs.texi     |  9 ++++++
>   libavdevice/lavfi.c | 80 +++++++++++++++++++++++++++++++++++++++++++++++++----
>   2 files changed, 84 insertions(+), 5 deletions(-)
>
>
> With this patch, it becomes possible to dump the subcc data, just like
> Anshul's program did, using the ffmpeg command-line tool.
>
> With a decoder, hopefully, it would be possible to use them like any kind of
> text subtitles.
>
> It requires using "-f lavfi -i movie=file" instead of just "-i file". I am
> not sure what the long term solution would be: implementing that really at
> the demuxer level, including frame reordering, or acknowledging that the
> protocol/demuxer/decoder stack model is too limited for some features
> (including, but not limited to, this one) and move to a more general model,
> possibly based on complex graphs.
>
>
> diff --git a/doc/indevs.texi b/doc/indevs.texi
> index 93fbbe8..cf948c6 100644
> --- a/doc/indevs.texi
> +++ b/doc/indevs.texi
> @@ -324,6 +324,9 @@ number starting from 0 corresponding to the mapped input stream
>   generated by the device.
>   The first unlabelled output is automatically assigned to the "out0"
>   label, but all the others need to be specified explicitly.
> +The suffix "+subcc" can be appended to the output label to create an extra
> +stream with the closed captions packets attached to that output
> +(experimental).
>   
>   If not specified defaults to the filename specified for the input
>   device.
> @@ -371,6 +374,12 @@ Read an audio stream and a video stream and play it back with
>   ffplay -f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
>   @end example
>   
> + at item
> +Dump decoded frames to images and closed captions to a file (experimental):
> + at example
> +ffmpeg -f lavfi -i "movie=test.ts[out0+subcc]" -map v frame%08d.png -map s -c copy -f rawvideo subcc.bin
> + at end example
> +
>   @end itemize
>   
>   @section libdc1394
> diff --git a/libavdevice/lavfi.c b/libavdevice/lavfi.c
> index 1ea7ea7..83fe490 100644
> --- a/libavdevice/lavfi.c
> +++ b/libavdevice/lavfi.c
> @@ -51,7 +51,10 @@ typedef struct {
>       int *sink_stream_map;
>       int *sink_eof;
>       int *stream_sink_map;
> +    int *sink_stream_subcc_map;
>       AVFrame *decoded_frame;
> +    int nb_sinks;
> +    AVPacket subcc_packet;
>   } LavfiContext;
>   
>   static int *create_all_formats(int n)
> @@ -82,6 +85,7 @@ av_cold static int lavfi_read_close(AVFormatContext *avctx)
>       av_freep(&lavfi->sink_stream_map);
>       av_freep(&lavfi->sink_eof);
>       av_freep(&lavfi->stream_sink_map);
> +    av_freep(&lavfi->sink_stream_subcc_map);
>       av_freep(&lavfi->sinks);
>       avfilter_graph_free(&lavfi->graph);
>       av_frame_free(&lavfi->decoded_frame);
> @@ -89,6 +93,27 @@ av_cold static int lavfi_read_close(AVFormatContext *avctx)
>       return 0;
>   }
>   
> +static int create_subcc_streams(AVFormatContext *avctx)
> +{
> +    LavfiContext *lavfi = avctx->priv_data;
> +    AVStream *st;
> +    int stream_idx, sink_idx;
> +
> +    for (stream_idx = 0; stream_idx < lavfi->nb_sinks; stream_idx++) {
> +        sink_idx = lavfi->stream_sink_map[stream_idx];
> +        if (lavfi->sink_stream_subcc_map[sink_idx]) {
> +            lavfi->sink_stream_subcc_map[sink_idx] = avctx->nb_streams;
> +            if (!(st = avformat_new_stream(avctx, NULL)))
> +                return AVERROR(ENOMEM);
> +            st->codec->codec_id = AV_CODEC_ID_CEA_708;
> +            st->codec->codec_type = AVMEDIA_TYPE_SUBTITLE;
> +        } else {
> +            lavfi->sink_stream_subcc_map[sink_idx] = -1;
> +        }
> +    }
> +    return 0;
> +}
> +
>   av_cold static int lavfi_read_header(AVFormatContext *avctx)
>   {
>       LavfiContext *lavfi = avctx->priv_data;
> @@ -153,6 +178,7 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>   
>       /* count the outputs */
>       for (n = 0, inout = output_links; inout; n++, inout = inout->next);
> +    lavfi->nb_sinks = n;
>   
>       if (!(lavfi->sink_stream_map = av_malloc(sizeof(int) * n)))
>           FAIL(AVERROR(ENOMEM));
> @@ -160,6 +186,8 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>           FAIL(AVERROR(ENOMEM));
>       if (!(lavfi->stream_sink_map = av_malloc(sizeof(int) * n)))
>           FAIL(AVERROR(ENOMEM));
> +    if (!(lavfi->sink_stream_subcc_map = av_malloc(sizeof(int) * n)))
> +        FAIL(AVERROR(ENOMEM));
>   
>       for (i = 0; i < n; i++)
>           lavfi->stream_sink_map[i] = -1;
> @@ -167,10 +195,10 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>       /* parse the output link names - they need to be of the form out0, out1, ...
>        * create a mapping between them and the streams */
>       for (i = 0, inout = output_links; inout; i++, inout = inout->next) {
> -        int stream_idx;
> +        int stream_idx, use_subcc = 0;
>           if (!strcmp(inout->name, "out"))
>               stream_idx = 0;
> -        else if (sscanf(inout->name, "out%d\n", &stream_idx) != 1) {
> +        else if (sscanf(inout->name, "out%d+subcc%n\n", &stream_idx, &use_subcc) != 1) {
>               av_log(avctx,  AV_LOG_ERROR,
>                      "Invalid outpad name '%s'\n", inout->name);
>               FAIL(AVERROR(EINVAL));
> @@ -200,6 +228,7 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>           }
>           lavfi->sink_stream_map[i] = stream_idx;
>           lavfi->stream_sink_map[stream_idx] = i;
> +        lavfi->sink_stream_subcc_map[i] = !!use_subcc;
>       }
>   
>       /* for each open output create a corresponding stream */
> @@ -211,7 +240,7 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>       }
>   
>       /* create a sink for each output and connect them to the graph */
> -    lavfi->sinks = av_malloc(sizeof(AVFilterContext *) * avctx->nb_streams);
> +    lavfi->sinks = av_malloc(sizeof(AVFilterContext *) * lavfi->nb_sinks);
>       if (!lavfi->sinks)
>           FAIL(AVERROR(ENOMEM));
>   
> @@ -271,7 +300,7 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>       }
>   
>       /* fill each stream with the information in the corresponding sink */
> -    for (i = 0; i < avctx->nb_streams; i++) {
> +    for (i = 0; i < lavfi->nb_sinks; i++) {
>           AVFilterLink *link = lavfi->sinks[lavfi->stream_sink_map[i]]->inputs[0];
>           AVStream *st = avctx->streams[i];
>           st->codec->codec_type = link->type;
> @@ -302,6 +331,9 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
>           }
>       }
>   
> +    if ((ret = create_subcc_streams(avctx)) < 0)
> +        FAIL(ret);
> +
>       if (!(lavfi->decoded_frame = av_frame_alloc()))
>           FAIL(AVERROR(ENOMEM));
>   
> @@ -314,6 +346,30 @@ end:
>       return ret;
>   }
>   
> +static int create_subcc_packet(AVFormatContext *avctx, AVFrame *frame,
> +                               int sink_idx)
> +{
> +    LavfiContext *lavfi = avctx->priv_data;
> +    AVFrameSideData *sd;
> +    int stream_idx, i, ret;
> +
> +    if ((stream_idx = lavfi->sink_stream_subcc_map[sink_idx]) < 0)
> +        return 0;
> +    for (i = 0; i < frame->nb_side_data; i++)
> +        if (frame->side_data[i]->type == AV_FRAME_DATA_A53_CC)
> +            break;
> +    if (i >= frame->nb_side_data)
> +        return 0;
> +    sd = frame->side_data[i];
> +    if ((ret = av_new_packet(&lavfi->subcc_packet, sd->size)) < 0)
> +        return ret;
> +    memcpy(lavfi->subcc_packet.data, sd->data, sd->size);
> +    lavfi->subcc_packet.stream_index = stream_idx;
> +    lavfi->subcc_packet.pts = frame->pts;
> +    lavfi->subcc_packet.pos = av_frame_get_pkt_pos(frame);
> +    return 0;
> +}
> +
>   static int lavfi_read_packet(AVFormatContext *avctx, AVPacket *pkt)
>   {
>       LavfiContext *lavfi = avctx->priv_data;
> @@ -325,9 +381,17 @@ static int lavfi_read_packet(AVFormatContext *avctx, AVPacket *pkt)
>       int ret, i;
>       int size = 0;
>   
> +    if (lavfi->subcc_packet.size) {
> +        *pkt = lavfi->subcc_packet;
> +        av_init_packet(&lavfi->subcc_packet);
> +        lavfi->subcc_packet.size = 0;
> +        lavfi->subcc_packet.data = NULL;
> +        return pkt->size;
> +    }
> +
>       /* iterate through all the graph sinks. Select the sink with the
>        * minimum PTS */
> -    for (i = 0; i < avctx->nb_streams; i++) {
> +    for (i = 0; i < lavfi->nb_sinks; i++) {
>           AVRational tb = lavfi->sinks[i]->inputs[0]->time_base;
>           double d;
>           int ret;
> @@ -401,6 +465,12 @@ static int lavfi_read_packet(AVFormatContext *avctx, AVPacket *pkt)
>           av_bprint_finalize(&meta_buf, NULL);
>       }
>   
> +    if ((ret = create_subcc_packet(avctx, frame, min_pts_sink_idx)) < 0) {
> +        av_frame_unref(frame);
> +        av_packet_unref(pkt);
> +        return ret;
> +    }
> +
>       pkt->stream_index = stream_idx;
>       pkt->pts = frame->pts;
>       pkt->pos = av_frame_get_pkt_pos(frame);

Hi
I was patched my git with both of this patch,
I am unable to run the code using below command,
./ffmpeg_g f lavfi -i "movie=test.ts[out0+subcc]" -map v frame%08d.png 
-map s -c copy -f rawvideo subcc.bin
I kept test.ts file in same folder as ffmpeg_g.
ffmpeg gives me error
movie=test.ts[out0+subcc]: No such file or directory

I have never given the movie after i, but as per the texi file this is 
what i understood.

Thanks
Anshul


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