Function flv_write_packet

libavformat/flvenc.c:1208–1484

}

static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
{
    AVIOContext *pb      = s->pb;
    AVCodecParameters *par = s->streams[pkt->stream_index]->codecpar;
    FLVContext *flv      = s->priv_data;
    unsigned ts;
    int size = pkt->size;
    uint8_t *data = NULL;
    uint8_t frametype = pkt->flags & AV_PKT_FLAG_KEY ? FLV_FRAME_KEY : FLV_FRAME_INTER;
    int flags = -1, flags_size, ret = 0;
    int64_t cur_offset = avio_tell(pb);
    int track_idx = flv->track_idx_map[pkt->stream_index];

    int extended_audio = (par->codec_id == AV_CODEC_ID_AAC && track_idx)
                            || (par->codec_id == AV_CODEC_ID_MP3 && track_idx)
                            || par->codec_id == AV_CODEC_ID_OPUS
                            || par->codec_id == AV_CODEC_ID_FLAC
                            || par->codec_id == AV_CODEC_ID_AC3
                            || par->codec_id == AV_CODEC_ID_EAC3;

    if (extended_audio)
        flags_size = 5;
    else if (par->codec_id == AV_CODEC_ID_VP6F || par->codec_id == AV_CODEC_ID_VP6A ||
             par->codec_id == AV_CODEC_ID_VP6  || par->codec_id == AV_CODEC_ID_AAC)
        flags_size = 2;
    else if (par->codec_id == AV_CODEC_ID_H264 || par->codec_id == AV_CODEC_ID_MPEG4 ||
             par->codec_id == AV_CODEC_ID_HEVC || par->codec_id == AV_CODEC_ID_AV1 ||
             par->codec_id == AV_CODEC_ID_VP9  || par->codec_id == AV_CODEC_ID_VVC)
        flags_size = 5;
    else
        flags_size = 1;

    if ((par->codec_type == AVMEDIA_TYPE_VIDEO || par->codec_type == AVMEDIA_TYPE_AUDIO) && track_idx)
        flags_size += 2; // additional header bytes for multi-track flv

    if ((par->codec_id == AV_CODEC_ID_HEVC || par->codec_id == AV_CODEC_ID_VVC ||
        (par->codec_id == AV_CODEC_ID_H264 && track_idx))
            && pkt->pts != pkt->dts)
        flags_size += 3;

    if (par->codec_id == AV_CODEC_ID_AAC || par->codec_id == AV_CODEC_ID_H264
            || par->codec_id == AV_CODEC_ID_MPEG4 || par->codec_id == AV_CODEC_ID_HEVC
            || par->codec_id == AV_CODEC_ID_VVC
            || par->codec_id == AV_CODEC_ID_AV1 || par->codec_id == AV_CODEC_ID_VP9
            || par->codec_id == AV_CODEC_ID_OPUS || par->codec_id == AV_CODEC_ID_FLAC) {
        size_t side_size;
        uint8_t *side = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA, &side_size);
        if (side && side_size > 0 && (side_size != par->extradata_size || memcmp(side, par->extradata, side_size))) {
            ret = ff_alloc_extradata(par, side_size);
            if (ret < 0)
                return ret;
            memcpy(par->extradata, side, side_size);
            flv_write_codec_header(s, par, pkt->dts, pkt->stream_index);
        }
        flv_write_metadata_packet(s, par, pkt->dts, pkt->stream_index);
    }

    if (flv->delay == AV_NOPTS_VALUE)