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

[Paul B Mahol <onemda@gmail.com>]

On 2/5/23, Gyan Doshi <ffmpeg@gyani.pro> wrote:
>
>
> On 2023-02-04 04:12 pm, Gyan Doshi wrote:
>>
>>
>> On 2023-02-04 04:02 pm, Paul B Mahol wrote:
>>> On 2/4/23, Gyan Doshi <ffmpeg@gyani.pro> wrote:
>>>>
>>>> On 2023-02-04 03:46 pm, Paul B Mahol wrote:
>>>>> On 2/4/23, Gyan Doshi <ffmpeg@gyani.pro> wrote:
>>>>>> On 2023-02-03 09:04 pm, Andreas Rheinhardt wrote:
>>>>>>> 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)?
>>>>>> This option together with meta_period is for CLI users. Similar to
>>>>>> drawtext's textfile + reload.
>>>>>> It's been used in production for over a year at a client. Think it
>>>>>> will
>>>>>> be broadly useful.
>>>>> Not everything that is useful now is correct on long term.
>>>>>
>>>>> Muxer specific metadata handling by reading from files is big hack.
>>>> What would you suggest?
>>> There should be way to handle this generically see Anton's patch that
>>> adds new AVOption type.
>> Link?
>
> So, I only found his patch to load filter options from files, but that's
> only inside filtergraphs.
>
> Anyway, this option is for dynamic metadata. Which means that even
> meta_period would have to be a generic lavf option.
> But most muxers don't emit metadata post-header.  In fact, flvenc is the
> only muxer that makes use of
> AV***_EVENT_FLAG_METADATA_UPDATED.  So, we will need a new AVFMT flag to
> avoid reloading of file metadata in all other cases.
> Seems overkill for something useful in one muxer.
>

Please ask Anton for opinion about this one.


> Regards,
> Gyan
>
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