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

[Gyan Doshi <ffmpeg@gyani.pro>]

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?

>
> Also those strcmp() spaghetti lines are unacceptable.

I didn't add those, only shifted them.

Regards,
Gyan

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