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

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

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.

Also those strcmp() spaghetti lines are unacceptable.
_______________________________________________
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".