/* * FLV muxer * Copyright (c) 2003 The FFmpeg Project * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "libavutil/intreadwrite.h" #include "libavutil/dict.h" #include "libavutil/intfloat.h" #include "libavutil/avassert.h" #include "avc.h" #include "avformat.h" #include "flv.h" #include "internal.h" #include "metadata.h" static const AVCodecTag flv_video_codec_ids[] = { { AV_CODEC_ID_FLV1, FLV_CODECID_H263 }, { AV_CODEC_ID_H263, FLV_CODECID_REALH263 }, { AV_CODEC_ID_MPEG4, FLV_CODECID_MPEG4 }, { AV_CODEC_ID_FLASHSV, FLV_CODECID_SCREEN }, { AV_CODEC_ID_FLASHSV2, FLV_CODECID_SCREEN2 }, { AV_CODEC_ID_VP6F, FLV_CODECID_VP6 }, { AV_CODEC_ID_VP6, FLV_CODECID_VP6 }, { AV_CODEC_ID_VP6A, FLV_CODECID_VP6A }, { AV_CODEC_ID_H264, FLV_CODECID_H264 }, { AV_CODEC_ID_NONE, 0 } }; static const AVCodecTag flv_audio_codec_ids[] = { { AV_CODEC_ID_MP3, FLV_CODECID_MP3 >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_PCM_U8, FLV_CODECID_PCM >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_PCM_S16BE, FLV_CODECID_PCM >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_PCM_S16LE, FLV_CODECID_PCM_LE >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_ADPCM_SWF, FLV_CODECID_ADPCM >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_AAC, FLV_CODECID_AAC >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_NELLYMOSER, FLV_CODECID_NELLYMOSER >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_PCM_MULAW, FLV_CODECID_PCM_MULAW >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_PCM_ALAW, FLV_CODECID_PCM_ALAW >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_SPEEX, FLV_CODECID_SPEEX >> FLV_AUDIO_CODECID_OFFSET }, { AV_CODEC_ID_NONE, 0 } }; typedef struct FLVContext { int reserved; int64_t duration_offset; int64_t filesize_offset; int64_t duration; int64_t delay; ///< first dts delay (needed for AVC & Speex) } FLVContext; typedef struct FLVStreamContext { int64_t last_ts; ///< last timestamp for each stream } FLVStreamContext; static int get_audio_flags(AVFormatContext *s, AVCodecContext *enc) { int flags = (enc->bits_per_coded_sample == 16) ? FLV_SAMPLESSIZE_16BIT : FLV_SAMPLESSIZE_8BIT; if (enc->codec_id == AV_CODEC_ID_AAC) // specs force these parameters return FLV_CODECID_AAC | FLV_SAMPLERATE_44100HZ | FLV_SAMPLESSIZE_16BIT | FLV_STEREO; else if (enc->codec_id == AV_CODEC_ID_SPEEX) { if (enc->sample_rate != 16000) { av_log(s, AV_LOG_ERROR, "FLV only supports wideband (16kHz) Speex audio\n"); return AVERROR(EINVAL); } if (enc->channels != 1) { av_log(s, AV_LOG_ERROR, "FLV only supports mono Speex audio\n"); return AVERROR(EINVAL); } return FLV_CODECID_SPEEX | FLV_SAMPLERATE_11025HZ | FLV_SAMPLESSIZE_16BIT; } else { switch (enc->sample_rate) { case 44100: flags |= FLV_SAMPLERATE_44100HZ; break; case 22050: flags |= FLV_SAMPLERATE_22050HZ; break; case 11025: flags |= FLV_SAMPLERATE_11025HZ; break; case 16000: // nellymoser only case 8000: // nellymoser only case 5512: // not MP3 if (enc->codec_id != AV_CODEC_ID_MP3) { flags |= FLV_SAMPLERATE_SPECIAL; break; } default: av_log(s, AV_LOG_ERROR, "FLV does not support sample rate %d, " "choose from (44100, 22050, 11025)\n", enc->sample_rate); return AVERROR(EINVAL); } } if (enc->channels > 1) flags |= FLV_STEREO; switch (enc->codec_id) { case AV_CODEC_ID_MP3: flags |= FLV_CODECID_MP3 | FLV_SAMPLESSIZE_16BIT; break; case AV_CODEC_ID_PCM_U8: flags |= FLV_CODECID_PCM | FLV_SAMPLESSIZE_8BIT; break; case AV_CODEC_ID_PCM_S16BE: flags |= FLV_CODECID_PCM | FLV_SAMPLESSIZE_16BIT; break; case AV_CODEC_ID_PCM_S16LE: flags |= FLV_CODECID_PCM_LE | FLV_SAMPLESSIZE_16BIT; break; case AV_CODEC_ID_ADPCM_SWF: flags |= FLV_CODECID_ADPCM | FLV_SAMPLESSIZE_16BIT; break; case AV_CODEC_ID_NELLYMOSER: if (enc->sample_rate == 8000) flags |= FLV_CODECID_NELLYMOSER_8KHZ_MONO | FLV_SAMPLESSIZE_16BIT; else if (enc->sample_rate == 16000) flags |= FLV_CODECID_NELLYMOSER_16KHZ_MONO | FLV_SAMPLESSIZE_16BIT; else flags |= FLV_CODECID_NELLYMOSER | FLV_SAMPLESSIZE_16BIT; break; case AV_CODEC_ID_PCM_MULAW: flags = FLV_CODECID_PCM_MULAW | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT; break; case AV_CODEC_ID_PCM_ALAW: flags = FLV_CODECID_PCM_ALAW | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT; break; case 0: flags |= enc->codec_tag << 4; break; default: av_log(s, AV_LOG_ERROR, "Audio codec '%s' not compatible with FLV\n", avcodec_get_name(enc->codec_id)); return AVERROR(EINVAL); } return flags; } static void put_amf_string(AVIOContext *pb, const char *str) { size_t len = strlen(str); avio_wb16(pb, len); avio_write(pb, str, len); } static void put_avc_eos_tag(AVIOContext *pb, unsigned ts) { avio_w8(pb, FLV_TAG_TYPE_VIDEO); avio_wb24(pb, 5); /* Tag Data Size */ avio_wb24(pb, ts); /* lower 24 bits of timestamp in ms */ avio_w8(pb, (ts >> 24) & 0x7F); /* MSB of ts in ms */ avio_wb24(pb, 0); /* StreamId = 0 */ avio_w8(pb, 23); /* ub[4] FrameType = 1, ub[4] CodecId = 7 */ avio_w8(pb, 2); /* AVC end of sequence */ avio_wb24(pb, 0); /* Always 0 for AVC EOS. */ avio_wb32(pb, 16); /* Size of FLV tag */ } static void put_amf_double(AVIOContext *pb, double d) { avio_w8(pb, AMF_DATA_TYPE_NUMBER); avio_wb64(pb, av_double2int(d)); } static void put_amf_bool(AVIOContext *pb, int b) { avio_w8(pb, AMF_DATA_TYPE_BOOL); avio_w8(pb, !!b); } static int flv_write_header(AVFormatContext *s) { AVIOContext *pb = s->pb; FLVContext *flv = s->priv_data; AVCodecContext *audio_enc = NULL, *video_enc = NULL, *data_enc = NULL; int i, metadata_count = 0; double framerate = 0.0; int64_t metadata_size_pos, data_size, metadata_count_pos; AVDictionaryEntry *tag = NULL; for (i = 0; i < s->nb_streams; i++) { AVCodecContext *enc = s->streams[i]->codec; FLVStreamContext *sc; switch (enc->codec_type) { case AVMEDIA_TYPE_VIDEO: if (s->streams[i]->avg_frame_rate.den && s->streams[i]->avg_frame_rate.num) { framerate = av_q2d(s->streams[i]->avg_frame_rate); } if (video_enc) { av_log(s, AV_LOG_ERROR, "at most one video stream is supported in flv\n"); return AVERROR(EINVAL); } video_enc = enc; if (enc->codec_tag == 0) { av_log(s, AV_LOG_ERROR, "Video codec '%s' for stream %d is not compatible with FLV\n", avcodec_get_name(enc->codec_id), i); return AVERROR(EINVAL); } if (enc->codec_id == AV_CODEC_ID_MPEG4 || enc->codec_id == AV_CODEC_ID_H263) { int error = enc->strict_std_compliance > FF_COMPLIANCE_UNOFFICIAL; av_log(s, error ? AV_LOG_ERROR : AV_LOG_WARNING, "Codec %s is not supported in the official FLV specification,\n", avcodec_get_name(enc->codec_id)); if (error) { av_log(s, AV_LOG_ERROR, "use vstrict=-1 / -strict -1 to use it anyway.\n"); return AVERROR(EINVAL); } } break; case AVMEDIA_TYPE_AUDIO: if (audio_enc) { av_log(s, AV_LOG_ERROR, "at most one audio stream is supported in flv\n"); return AVERROR(EINVAL); } audio_enc = enc; if (get_audio_flags(s, enc) < 0) return AVERROR_INVALIDDATA; if (enc->codec_id == AV_CODEC_ID_PCM_S16BE) av_log(s, AV_LOG_WARNING, "16-bit big-endian audio in flv is valid but most likely unplayable (hardware dependent); use s16le\n"); break; case AVMEDIA_TYPE_DATA: if (enc->codec_id != AV_CODEC_ID_TEXT && enc->codec_id != AV_CODEC_ID_NONE) { av_log(s, AV_LOG_ERROR, "Data codec '%s' for stream %d is not compatible with FLV\n", avcodec_get_name(enc->codec_id), i); return AVERROR_INVALIDDATA; } data_enc = enc; break; default: av_log(s, AV_LOG_ERROR, "Codec type '%s' for stream %d is not compatible with FLV\n", av_get_media_type_string(enc->codec_type), i); return AVERROR(EINVAL); } avpriv_set_pts_info(s->streams[i], 32, 1, 1000); /* 32 bit pts in ms */ sc = av_mallocz(sizeof(FLVStreamContext)); if (!sc) return AVERROR(ENOMEM); s->streams[i]->priv_data = sc; sc->last_ts = -1; } flv->delay = AV_NOPTS_VALUE; avio_write(pb, "FLV", 3); avio_w8(pb, 1); avio_w8(pb, FLV_HEADER_FLAG_HASAUDIO * !!audio_enc + FLV_HEADER_FLAG_HASVIDEO * !!video_enc); avio_wb32(pb, 9); avio_wb32(pb, 0); for (i = 0; i < s->nb_streams; i++) if (s->streams[i]->codec->codec_tag == 5) { avio_w8(pb, 8); // message type avio_wb24(pb, 0); // include flags avio_wb24(pb, 0); // time stamp avio_wb32(pb, 0); // reserved avio_wb32(pb, 11); // size flv->reserved = 5; } /* write meta_tag */ avio_w8(pb, 18); // tag type META metadata_size_pos = avio_tell(pb); avio_wb24(pb, 0); // size of data part (sum of all parts below) avio_wb24(pb, 0); // timestamp avio_wb32(pb, 0); // reserved /* now data of data_size size */ /* first event name as a string */ avio_w8(pb, AMF_DATA_TYPE_STRING); put_amf_string(pb, "onMetaData"); // 12 bytes /* mixed array (hash) with size and string/type/data tuples */ avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY); metadata_count_pos = avio_tell(pb); metadata_count = 4 * !!video_enc + 5 * !!audio_enc + 1 * !!data_enc + 2; // +2 for duration and file size avio_wb32(pb, metadata_count); put_amf_string(pb, "duration"); flv->duration_offset= avio_tell(pb); // fill in the guessed duration, it'll be corrected later if incorrect put_amf_double(pb, s->duration / AV_TIME_BASE); if (video_enc) { put_amf_string(pb, "width"); put_amf_double(pb, video_enc->width); put_amf_string(pb, "height"); put_amf_double(pb, video_enc->height); put_amf_string(pb, "videodatarate"); put_amf_double(pb, video_enc->bit_rate / 1024.0); if (framerate != 0.0) { put_amf_string(pb, "framerate"); put_amf_double(pb, framerate); metadata_count++; } put_amf_string(pb, "videocodecid"); put_amf_double(pb, video_enc->codec_tag); } if (audio_enc) { put_amf_string(pb, "audiodatarate"); put_amf_double(pb, audio_enc->bit_rate / 1024.0); put_amf_string(pb, "audiosamplerate"); put_amf_double(pb, audio_enc->sample_rate); put_amf_string(pb, "audiosamplesize"); put_amf_double(pb, audio_enc->codec_id == AV_CODEC_ID_PCM_U8 ? 8 : 16); put_amf_string(pb, "stereo"); put_amf_bool(pb, audio_enc->channels == 2); put_amf_string(pb, "audiocodecid"); put_amf_double(pb, audio_enc->codec_tag); } if (data_enc) { put_amf_string(pb, "datastream"); put_amf_double(pb, 0.0); } while ((tag = av_dict_get(s->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) { 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") ){ 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++; } put_amf_string(pb, "filesize"); flv->filesize_offset = avio_tell(pb); put_amf_double(pb, 0); // delayed write put_amf_string(pb, ""); avio_w8(pb, AMF_END_OF_OBJECT); /* write total size of tag */ data_size = avio_tell(pb) - metadata_size_pos - 10; avio_seek(pb, metadata_count_pos, SEEK_SET); avio_wb32(pb, metadata_count); avio_seek(pb, metadata_size_pos, SEEK_SET); avio_wb24(pb, data_size); avio_skip(pb, data_size + 10 - 3); avio_wb32(pb, data_size + 11); for (i = 0; i < s->nb_streams; i++) { AVCodecContext *enc = s->streams[i]->codec; if (enc->codec_id == AV_CODEC_ID_AAC || enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4) { int64_t pos; avio_w8(pb, enc->codec_type == AVMEDIA_TYPE_VIDEO ? FLV_TAG_TYPE_VIDEO : FLV_TAG_TYPE_AUDIO); avio_wb24(pb, 0); // size patched later avio_wb24(pb, 0); // ts avio_w8(pb, 0); // ts ext avio_wb24(pb, 0); // streamid pos = avio_tell(pb); if (enc->codec_id == AV_CODEC_ID_AAC) { avio_w8(pb, get_audio_flags(s, enc)); avio_w8(pb, 0); // AAC sequence header avio_write(pb, enc->extradata, enc->extradata_size); } else { avio_w8(pb, enc->codec_tag | FLV_FRAME_KEY); // flags avio_w8(pb, 0); // AVC sequence header avio_wb24(pb, 0); // composition time ff_isom_write_avcc(pb, enc->extradata, enc->extradata_size); } data_size = avio_tell(pb) - pos; avio_seek(pb, -data_size - 10, SEEK_CUR); avio_wb24(pb, data_size); avio_skip(pb, data_size + 10 - 3); avio_wb32(pb, data_size + 11); // previous tag size } } return 0; } static int flv_write_trailer(AVFormatContext *s) { int64_t file_size; AVIOContext *pb = s->pb; FLVContext *flv = s->priv_data; int i; /* Add EOS tag */ for (i = 0; i < s->nb_streams; i++) { AVCodecContext *enc = s->streams[i]->codec; FLVStreamContext *sc = s->streams[i]->priv_data; if (enc->codec_type == AVMEDIA_TYPE_VIDEO && (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4)) put_avc_eos_tag(pb, sc->last_ts); } file_size = avio_tell(pb); /* update information */ if (avio_seek(pb, flv->duration_offset, SEEK_SET) < 0) av_log(s, AV_LOG_WARNING, "Failed to update header with correct duration.\n"); else put_amf_double(pb, flv->duration / (double)1000); if (avio_seek(pb, flv->filesize_offset, SEEK_SET) < 0) av_log(s, AV_LOG_WARNING, "Failed to update header with correct filesize.\n"); else put_amf_double(pb, file_size); avio_seek(pb, file_size, SEEK_SET); return 0; } static int flv_write_packet(AVFormatContext *s, AVPacket *pkt) { AVIOContext *pb = s->pb; AVCodecContext *enc = s->streams[pkt->stream_index]->codec; FLVContext *flv = s->priv_data; FLVStreamContext *sc = s->streams[pkt->stream_index]->priv_data; unsigned ts; int size = pkt->size; uint8_t *data = NULL; int flags = -1, flags_size, ret; if (enc->codec_id == AV_CODEC_ID_VP6F || enc->codec_id == AV_CODEC_ID_VP6A || enc->codec_id == AV_CODEC_ID_VP6 || enc->codec_id == AV_CODEC_ID_AAC) flags_size = 2; else if (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4) flags_size = 5; else flags_size = 1; switch (enc->codec_type) { case AVMEDIA_TYPE_VIDEO: avio_w8(pb, FLV_TAG_TYPE_VIDEO); flags = enc->codec_tag; if (flags == 0) { av_log(s, AV_LOG_ERROR, "Video codec '%s' is not compatible with FLV\n", avcodec_get_name(enc->codec_id)); return AVERROR(EINVAL); } flags |= pkt->flags & AV_PKT_FLAG_KEY ? FLV_FRAME_KEY : FLV_FRAME_INTER; break; case AVMEDIA_TYPE_AUDIO: flags = get_audio_flags(s, enc); av_assert0(size); avio_w8(pb, FLV_TAG_TYPE_AUDIO); break; case AVMEDIA_TYPE_DATA: avio_w8(pb, FLV_TAG_TYPE_META); break; default: return AVERROR(EINVAL); } if (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4) { /* check if extradata looks like mp4 formated */ if (enc->extradata_size > 0 && *(uint8_t*)enc->extradata != 1) if ((ret = ff_avc_parse_nal_units_buf(pkt->data, &data, &size)) < 0) return ret; } else if (enc->codec_id == AV_CODEC_ID_AAC && pkt->size > 2 && (AV_RB16(pkt->data) & 0xfff0) == 0xfff0) { if (!s->streams[pkt->stream_index]->nb_frames) { av_log(s, AV_LOG_ERROR, "Malformed AAC bitstream detected: " "use the audio bitstream filter 'aac_adtstoasc' to fix it " "('-bsf:a aac_adtstoasc' option with ffmpeg)\n"); return AVERROR_INVALIDDATA; } av_log(s, AV_LOG_WARNING, "aac bitstream error\n"); } if (flv->delay == AV_NOPTS_VALUE) flv->delay = -pkt->dts; if (pkt->dts < -flv->delay) { av_log(s, AV_LOG_WARNING, "Packets are not in the proper order with respect to DTS\n"); return AVERROR(EINVAL); } ts = pkt->dts + flv->delay; // add delay to force positive dts /* check Speex packet duration */ if (enc->codec_id == AV_CODEC_ID_SPEEX && ts - sc->last_ts > 160) av_log(s, AV_LOG_WARNING, "Warning: Speex stream has more than " "8 frames per packet. Adobe Flash " "Player cannot handle this!\n"); if (sc->last_ts < ts) sc->last_ts = ts; if (size + flags_size >= 1<<24) { av_log(s, AV_LOG_ERROR, "Too large packet with size %u >= %u\n", size + flags_size, 1<<24); return AVERROR(EINVAL); } avio_wb24(pb, size + flags_size); avio_wb24(pb, ts & 0xFFFFFF); avio_w8(pb, (ts >> 24) & 0x7F); // timestamps are 32 bits _signed_ avio_wb24(pb, flv->reserved); if (enc->codec_type == AVMEDIA_TYPE_DATA) { int data_size; int64_t metadata_size_pos = avio_tell(pb); if (enc->codec_id == AV_CODEC_ID_TEXT) { // legacy FFmpeg magic? avio_w8(pb, AMF_DATA_TYPE_STRING); put_amf_string(pb, "onTextData"); avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY); avio_wb32(pb, 2); put_amf_string(pb, "type"); avio_w8(pb, AMF_DATA_TYPE_STRING); put_amf_string(pb, "Text"); put_amf_string(pb, "text"); avio_w8(pb, AMF_DATA_TYPE_STRING); put_amf_string(pb, pkt->data); put_amf_string(pb, ""); avio_w8(pb, AMF_END_OF_OBJECT); } else { // just pass the metadata through avio_write(pb, data ? data : pkt->data, size); } /* write total size of tag */ data_size = avio_tell(pb) - metadata_size_pos; avio_seek(pb, metadata_size_pos - 10, SEEK_SET); avio_wb24(pb, data_size); avio_seek(pb, data_size + 10 - 3, SEEK_CUR); avio_wb32(pb, data_size + 11); } else { av_assert1(flags>=0); avio_w8(pb,flags); if (enc->codec_id == AV_CODEC_ID_VP6) avio_w8(pb,0); if (enc->codec_id == AV_CODEC_ID_VP6F || enc->codec_id == AV_CODEC_ID_VP6A) { if (enc->extradata_size) avio_w8(pb, enc->extradata[0]); else avio_w8(pb, ((FFALIGN(enc->width, 16) - enc->width) << 4) | (FFALIGN(enc->height, 16) - enc->height)); } else if (enc->codec_id == AV_CODEC_ID_AAC) avio_w8(pb, 1); // AAC raw else if (enc->codec_id == AV_CODEC_ID_H264 || enc->codec_id == AV_CODEC_ID_MPEG4) { avio_w8(pb, 1); // AVC NALU avio_wb24(pb, pkt->pts - pkt->dts); } avio_write(pb, data ? data : pkt->data, size); avio_wb32(pb, size + flags_size + 11); // previous tag size flv->duration = FFMAX(flv->duration, pkt->pts + flv->delay + pkt->duration); } av_free(data); return pb->error; } AVOutputFormat ff_flv_muxer = { .name = "flv", .long_name = NULL_IF_CONFIG_SMALL("FLV (Flash Video)"), .mime_type = "video/x-flv", .extensions = "flv", .priv_data_size = sizeof(FLVContext), .audio_codec = CONFIG_LIBMP3LAME ? AV_CODEC_ID_MP3 : AV_CODEC_ID_ADPCM_SWF, .video_codec = AV_CODEC_ID_FLV1, .write_header = flv_write_header, .write_packet = flv_write_packet, .write_trailer = flv_write_trailer, .codec_tag = (const AVCodecTag* const []) { flv_video_codec_ids, flv_audio_codec_ids, 0 }, .flags = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS | AVFMT_TS_NONSTRICT, };