Re: [FFmpeg-devel] [PATCH v2 2/2] avformat/flvenc: add option to read metadata from file

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

Gyan Doshi:
> Useful, in conjuntion with option meta_period, to vary metadata during
> stream.
> 
> File format is ffmetadata.
> ---
>  configure            |   2 +-
>  doc/muxers.texi      |   3 +
>  libavformat/flvenc.c | 133 +++++++++++++++++++++++++++++++++----------
>  3 files changed, 107 insertions(+), 31 deletions(-)
> 
> diff --git a/configure b/configure
> index 9d78a244a3..de371632c4 100755
> --- a/configure
> +++ b/configure
> @@ -3433,7 +3433,7 @@ eac3_demuxer_select="ac3_parser"
>  f4v_muxer_select="mov_muxer"
>  fifo_muxer_deps="threads"
>  flac_demuxer_select="flac_parser"
> -flv_muxer_select="aac_adtstoasc_bsf"
> +flv_muxer_select="aac_adtstoasc_bsf ffmetadata_demuxer"
>  gxf_muxer_select="pcm_rechunk_bsf"
>  hds_muxer_select="flv_muxer"
>  hls_demuxer_select="adts_header ac3_parser"
> diff --git a/doc/muxers.texi b/doc/muxers.texi
> index 02ecddf186..000c92b2a7 100644
> --- a/doc/muxers.texi
> +++ b/doc/muxers.texi
> @@ -555,6 +555,9 @@ With every video packet.
>  @end table
>  Note that metadata will always be re-emitted if a metadata update event is signalled.
>  
> +@item meta_filename
> +Specify a ffmetadata file from which to load metadata.
> +
>  @end table
>  
>  @anchor{framecrc}
> diff --git a/libavformat/flvenc.c b/libavformat/flvenc.c
> index d1c7a493d1..1332b18b41 100644
> --- a/libavformat/flvenc.c
> +++ b/libavformat/flvenc.c
> @@ -122,6 +122,10 @@ typedef struct FLVContext {
>      double framerate;
>      AVCodecParameters *data_par;
>  
> +    char *meta_filename;
> +    AVFormatContext *meta_ctx;
> +    AVDictionary *meta_dict;
> +
>      int flags;
>      int meta_period;
>  } FLVContext;
> @@ -277,6 +281,92 @@ static void put_amf_bool(AVIOContext *pb, int b)
>      avio_w8(pb, !!b);
>  }
>  
> +static int read_metadata_from_file(AVFormatContext *s, unsigned int ts, int header)
> +{
> +    FLVContext *flv = s->priv_data;
> +    const AVInputFormat *meta_format = NULL;
> +    AVDictionary *current_meta_dict = NULL;
> +    float timestamp = ts/1000.f;
> +    int ret;
> +
> +    if (!flv->meta_filename)
> +        return 0;
> +
> +    meta_format = av_find_input_format("ffmetadata");
> +    if (!meta_format) {
> +        av_log(s, AV_LOG_ERROR, "ffmetadata demuxer not found.\n");
> +        return AVERROR(ENOSYS);
> +    }
> +
> +    avformat_close_input(&flv->meta_ctx);
> +
> +    ret = avformat_open_input(&flv->meta_ctx, flv->meta_filename, meta_format, NULL);
> +    if (ret < 0) {
> +        av_log(s, AV_LOG_ERROR, "Failed to read metadata from file %s t: %f.", flv->meta_filename, timestamp);
> +        if (flv->meta_dict)
> +            av_log(s, AV_LOG_ERROR, " Continuing with old metadata.");
> +        av_log(s, AV_LOG_ERROR, "\n");
> +        return ret;
> +    }
> +
> +    if (flv->meta_dict) {
> +        av_dict_copy(&current_meta_dict, flv->meta_dict, 0);
> +        av_dict_free(&flv->meta_dict);
> +    }
> +
> +    ret = av_dict_copy(&flv->meta_dict, flv->meta_ctx->metadata, 0);
> +    if (ret < 0) {
> +        av_log(s, AV_LOG_ERROR, "Could not transfer metadata from %s at %f seconds. Continuing with old metadata.\n", flv->meta_filename, timestamp);
> +        av_dict_free(&flv->meta_dict);
> +        av_dict_copy(&flv->meta_dict, current_meta_dict, 0);
> +        av_dict_free(&current_meta_dict);
> +        return ret;
> +    }
> +
> +    av_log(s, AV_LOG_VERBOSE, "Metadata from file %s updated %s at %f seconds.\n", flv->meta_filename, header ? "in header" : "in video packet", timestamp);
> +    av_dict_free(&current_meta_dict);
> +    avformat_close_input(&flv->meta_ctx);
> +
> +    return 0;
> +}
> +
> +static int write_user_metadata_tag(AVFormatContext *s, AVDictionaryEntry *tag, AVIOContext *pb, int *metadata_count)
> +{
> +
> +    av_log(s, AV_LOG_DEBUG, "Writing tag %s with value %s count: %d\n", tag->key, tag->value, *metadata_count);
> +
> +    if(   !strcmp(tag->key, "width")
> +        ||!strcmp(tag->key, "height")
> +        ||!strcmp(tag->key, "videodatarate")
> +        ||!strcmp(tag->key, "framerate")
> +        ||!strcmp(tag->key, "videocodecid")
> +        ||!strcmp(tag->key, "audiodatarate")
> +        ||!strcmp(tag->key, "audiosamplerate")
> +        ||!strcmp(tag->key, "audiosamplesize")
> +        ||!strcmp(tag->key, "stereo")
> +        ||!strcmp(tag->key, "audiocodecid")
> +        ||!strcmp(tag->key, "duration")
> +        ||!strcmp(tag->key, "onMetaData")
> +        ||!strcmp(tag->key, "datasize")
> +        ||!strcmp(tag->key, "lasttimestamp")
> +        ||!strcmp(tag->key, "totalframes")
> +        ||!strcmp(tag->key, "hasAudio")
> +        ||!strcmp(tag->key, "hasVideo")
> +        ||!strcmp(tag->key, "hasCuePoints")
> +        ||!strcmp(tag->key, "hasMetadata")
> +        ||!strcmp(tag->key, "hasKeyframes")
> +    ){
> +        av_log(s, AV_LOG_DEBUG, "Ignoring metadata for %s\n", tag->key);
> +        return AVERROR(EINVAL);
> +    }
> +    put_amf_string(pb, tag->key);
> +    avio_w8(pb, AMF_DATA_TYPE_STRING);
> +    put_amf_string(pb, tag->value);
> +    (*metadata_count)++;
> +
> +    return 0;
> +}
> +
>  static void write_metadata(AVFormatContext *s, unsigned int ts)
>  {
>      AVIOContext *pb = s->pb;
> @@ -360,36 +450,11 @@ static void write_metadata(AVFormatContext *s, unsigned int ts)
>      }
>  
>      ff_standardize_creation_time(s);
> -    while ((tag = av_dict_iterate(s->metadata, tag))) {
> -        if(   !strcmp(tag->key, "width")
> -            ||!strcmp(tag->key, "height")
> -            ||!strcmp(tag->key, "videodatarate")
> -            ||!strcmp(tag->key, "framerate")
> -            ||!strcmp(tag->key, "videocodecid")
> -            ||!strcmp(tag->key, "audiodatarate")
> -            ||!strcmp(tag->key, "audiosamplerate")
> -            ||!strcmp(tag->key, "audiosamplesize")
> -            ||!strcmp(tag->key, "stereo")
> -            ||!strcmp(tag->key, "audiocodecid")
> -            ||!strcmp(tag->key, "duration")
> -            ||!strcmp(tag->key, "onMetaData")
> -            ||!strcmp(tag->key, "datasize")
> -            ||!strcmp(tag->key, "lasttimestamp")
> -            ||!strcmp(tag->key, "totalframes")
> -            ||!strcmp(tag->key, "hasAudio")
> -            ||!strcmp(tag->key, "hasVideo")
> -            ||!strcmp(tag->key, "hasCuePoints")
> -            ||!strcmp(tag->key, "hasMetadata")
> -            ||!strcmp(tag->key, "hasKeyframes")
> -        ){
> -            av_log(s, AV_LOG_DEBUG, "Ignoring metadata for %s\n", tag->key);
> -            continue;
> -        }
> -        put_amf_string(pb, tag->key);
> -        avio_w8(pb, AMF_DATA_TYPE_STRING);
> -        put_amf_string(pb, tag->value);
> -        metadata_count++;
> -    }
> +
> +    while (tag = av_dict_get(s->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))
> +        write_user_metadata_tag(s, tag, pb, &metadata_count);
> +    while (tag = av_dict_get(flv->meta_dict, "", tag, AV_DICT_IGNORE_SUFFIX))
> +        write_user_metadata_tag(s, tag, pb, &metadata_count);
>  
>      if (write_duration_filesize) {
>          put_amf_string(pb, "filesize");
> @@ -718,6 +783,7 @@ static int flv_write_header(AVFormatContext *s)
>      if (flv->flags & FLV_NO_METADATA) {
>          pb->seekable = 0;
>      } else {
> +        read_metadata_from_file(s, 0, 1);
>          write_metadata(s, 0);
>      }
>  
> @@ -880,6 +946,7 @@ static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
>      if (meta_upd_flag ||
>          (flv->meta_period == FLV_META_AT_KF        && par->codec_type == AVMEDIA_TYPE_VIDEO && (pkt->flags & AV_PKT_FLAG_KEY)) ||
>          (flv->meta_period == FLV_META_EVERY_PACKET && par->codec_type == AVMEDIA_TYPE_VIDEO )) {
> +        read_metadata_from_file(s, ts, 0);
>          write_metadata(s, ts);
>          if (meta_upd_flag)
>              s->event_flags &= ~AVSTREAM_EVENT_FLAG_METADATA_UPDATED;
> @@ -1053,6 +1120,11 @@ static void flv_deinit(AVFormatContext *s)
>      }
>      flv->filepositions = flv->head_filepositions = NULL;
>      flv->filepositions_count = 0;
> +
> +    if (flv->meta_dict)
> +        av_dict_free(&flv->meta_dict);
> +
> +    avformat_close_input(&flv->meta_ctx);
>  }
>  
>  static const AVOption options[] = {
> @@ -1066,6 +1138,7 @@ static const AVOption options[] = {
>      { "at_start",      "only once at start",        0, AV_OPT_TYPE_CONST, {.i64 = FLV_META_ONCE_AT_START}, INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "meta_period" },
>      { "at_keyframes",  "with every video keyframe", 0, AV_OPT_TYPE_CONST, {.i64 = FLV_META_AT_KF},         INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "meta_period" },
>      { "every_packet",  "with every video packet",   0, AV_OPT_TYPE_CONST, {.i64 = FLV_META_EVERY_PACKET},  INT_MIN, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM, "meta_period" },
> +    { "meta_filename", "ffmetadata file to import metadata", offsetof(FLVContext, meta_filename), AV_OPT_TYPE_STRING, {.str = NULL},  0, 0, AV_OPT_FLAG_ENCODING_PARAM },
>      { NULL },
>  };
>  

What does this achieve that can't be achieved by other means (namely by
an API-user updating the relevant metadata dictionaries)?

- Andreas

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