FFmpeg: libavformat/flvenc.c Source File

00001 /*
00002  * FLV muxer
00003  * Copyright (c) 2003 The FFmpeg Project
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "libavutil/intreadwrite.h"
00023 #include "libavutil/intfloat_readwrite.h"
00024 #include "avformat.h"
00025 #include "flv.h"
00026 #include "internal.h"
00027 #include "avc.h"
00028 #include "metadata.h"
00029 #include "libavutil/dict.h"
00030 
00031 #undef NDEBUG
00032 #include <assert.h>
00033 
00034 static const AVCodecTag flv_video_codec_ids[] = {
00035     {CODEC_ID_FLV1,    FLV_CODECID_H263  },
00036     {CODEC_ID_H263,    FLV_CODECID_REALH263},
00037     {CODEC_ID_MPEG4,   FLV_CODECID_MPEG4 },
00038     {CODEC_ID_FLASHSV, FLV_CODECID_SCREEN},
00039     {CODEC_ID_FLASHSV2, FLV_CODECID_SCREEN2},
00040     {CODEC_ID_VP6F,    FLV_CODECID_VP6   },
00041     {CODEC_ID_VP6,     FLV_CODECID_VP6   },
00042     {CODEC_ID_H264,    FLV_CODECID_H264  },
00043     {CODEC_ID_NONE,    0}
00044 };
00045 
00046 static const AVCodecTag flv_audio_codec_ids[] = {
00047     {CODEC_ID_MP3,       FLV_CODECID_MP3    >> FLV_AUDIO_CODECID_OFFSET},
00048     {CODEC_ID_PCM_U8,    FLV_CODECID_PCM    >> FLV_AUDIO_CODECID_OFFSET},
00049     {CODEC_ID_PCM_S16BE, FLV_CODECID_PCM    >> FLV_AUDIO_CODECID_OFFSET},
00050     {CODEC_ID_PCM_S16LE, FLV_CODECID_PCM_LE >> FLV_AUDIO_CODECID_OFFSET},
00051     {CODEC_ID_ADPCM_SWF, FLV_CODECID_ADPCM  >> FLV_AUDIO_CODECID_OFFSET},
00052     {CODEC_ID_AAC,       FLV_CODECID_AAC    >> FLV_AUDIO_CODECID_OFFSET},
00053     {CODEC_ID_NELLYMOSER, FLV_CODECID_NELLYMOSER >> FLV_AUDIO_CODECID_OFFSET},
00054     {CODEC_ID_SPEEX,     FLV_CODECID_SPEEX  >> FLV_AUDIO_CODECID_OFFSET},
00055     {CODEC_ID_NONE,      0}
00056 };
00057 
00058 typedef struct FLVContext {
00059     int reserved;
00060     int64_t duration_offset;
00061     int64_t filesize_offset;
00062     int64_t duration;
00063     int64_t delay;      
00064 } FLVContext;
00065 
00066 typedef struct FLVStreamContext {
00067     int64_t last_ts;    
00068 } FLVStreamContext;
00069 
00070 static int get_audio_flags(AVCodecContext *enc){
00071     int flags = (enc->bits_per_coded_sample == 16) ? FLV_SAMPLESSIZE_16BIT : FLV_SAMPLESSIZE_8BIT;
00072 
00073     if (enc->codec_id == CODEC_ID_AAC) // specs force these parameters
00074         return FLV_CODECID_AAC | FLV_SAMPLERATE_44100HZ | FLV_SAMPLESSIZE_16BIT | FLV_STEREO;
00075     else if (enc->codec_id == CODEC_ID_SPEEX) {
00076         if (enc->sample_rate != 16000) {
00077             av_log(enc, AV_LOG_ERROR, "flv only supports wideband (16kHz) Speex audio\n");
00078             return -1;
00079         }
00080         if (enc->channels != 1) {
00081             av_log(enc, AV_LOG_ERROR, "flv only supports mono Speex audio\n");
00082             return -1;
00083         }
00084         return FLV_CODECID_SPEEX | FLV_SAMPLERATE_11025HZ | FLV_SAMPLESSIZE_16BIT;
00085     } else {
00086     switch (enc->sample_rate) {
00087         case    44100:
00088             flags |= FLV_SAMPLERATE_44100HZ;
00089             break;
00090         case    22050:
00091             flags |= FLV_SAMPLERATE_22050HZ;
00092             break;
00093         case    11025:
00094             flags |= FLV_SAMPLERATE_11025HZ;
00095             break;
00096         case    16000: //nellymoser only
00097         case     8000: //nellymoser only
00098         case     5512: //not mp3
00099             if(enc->codec_id != CODEC_ID_MP3){
00100                 flags |= FLV_SAMPLERATE_SPECIAL;
00101                 break;
00102             }
00103         default:
00104             av_log(enc, AV_LOG_ERROR, "flv does not support that sample rate, choose from (44100, 22050, 11025).\n");
00105             return -1;
00106     }
00107     }
00108 
00109     if (enc->channels > 1) {
00110         flags |= FLV_STEREO;
00111     }
00112 
00113     switch(enc->codec_id){
00114     case CODEC_ID_MP3:
00115         flags |= FLV_CODECID_MP3    | FLV_SAMPLESSIZE_16BIT;
00116         break;
00117     case CODEC_ID_PCM_U8:
00118         flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_8BIT;
00119         break;
00120     case CODEC_ID_PCM_S16BE:
00121         flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_16BIT;
00122         break;
00123     case CODEC_ID_PCM_S16LE:
00124         flags |= FLV_CODECID_PCM_LE | FLV_SAMPLESSIZE_16BIT;
00125         break;
00126     case CODEC_ID_ADPCM_SWF:
00127         flags |= FLV_CODECID_ADPCM | FLV_SAMPLESSIZE_16BIT;
00128         break;
00129     case CODEC_ID_NELLYMOSER:
00130         if (enc->sample_rate == 8000) {
00131             flags |= FLV_CODECID_NELLYMOSER_8KHZ_MONO | FLV_SAMPLESSIZE_16BIT;
00132         } else if (enc->sample_rate == 16000) {
00133             flags |= FLV_CODECID_NELLYMOSER_16KHZ_MONO | FLV_SAMPLESSIZE_16BIT;
00134         } else {
00135             flags |= FLV_CODECID_NELLYMOSER | FLV_SAMPLESSIZE_16BIT;
00136         }
00137         break;
00138     case 0:
00139         flags |= enc->codec_tag<<4;
00140         break;
00141     default:
00142         av_log(enc, AV_LOG_ERROR, "codec not compatible with flv\n");
00143         return -1;
00144     }
00145 
00146     return flags;
00147 }
00148 
00149 static void put_amf_string(AVIOContext *pb, const char *str)
00150 {
00151     size_t len = strlen(str);
00152     avio_wb16(pb, len);
00153     avio_write(pb, str, len);
00154 }
00155 
00156 static void put_avc_eos_tag(AVIOContext *pb, unsigned ts) {
00157     avio_w8(pb, FLV_TAG_TYPE_VIDEO);
00158     avio_wb24(pb, 5);  /* Tag Data Size */
00159     avio_wb24(pb, ts);  /* lower 24 bits of timestamp in ms*/
00160     avio_w8(pb, (ts >> 24) & 0x7F);  /* MSB of ts in ms*/
00161     avio_wb24(pb, 0);  /* StreamId = 0 */
00162     avio_w8(pb, 23);  /* ub[4] FrameType = 1, ub[4] CodecId = 7 */
00163     avio_w8(pb, 2);  /* AVC end of sequence */
00164     avio_wb24(pb, 0);  /* Always 0 for AVC EOS. */
00165     avio_wb32(pb, 16);  /* Size of FLV tag */
00166 }
00167 
00168 static void put_amf_double(AVIOContext *pb, double d)
00169 {
00170     avio_w8(pb, AMF_DATA_TYPE_NUMBER);
00171     avio_wb64(pb, av_dbl2int(d));
00172 }
00173 
00174 static void put_amf_bool(AVIOContext *pb, int b) {
00175     avio_w8(pb, AMF_DATA_TYPE_BOOL);
00176     avio_w8(pb, !!b);
00177 }
00178 
00179 static int flv_write_header(AVFormatContext *s)
00180 {
00181     AVIOContext *pb = s->pb;
00182     FLVContext *flv = s->priv_data;
00183     AVCodecContext *audio_enc = NULL, *video_enc = NULL;
00184     int i, metadata_count = 0;
00185     double framerate = 0.0;
00186     int64_t metadata_size_pos, data_size, metadata_count_pos;
00187     AVDictionaryEntry *tag = NULL;
00188 
00189     for(i=0; i<s->nb_streams; i++){
00190         AVCodecContext *enc = s->streams[i]->codec;
00191         FLVStreamContext *sc;
00192         if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
00193             if (s->streams[i]->r_frame_rate.den && s->streams[i]->r_frame_rate.num) {
00194                 framerate = av_q2d(s->streams[i]->r_frame_rate);
00195             } else {
00196                 framerate = 1/av_q2d(s->streams[i]->codec->time_base);
00197             }
00198             video_enc = enc;
00199             if(enc->codec_tag == 0) {
00200                 av_log(enc, AV_LOG_ERROR, "video codec not compatible with flv\n");
00201                 return -1;
00202             }
00203         } else if (enc->codec_type == AVMEDIA_TYPE_AUDIO) {
00204             audio_enc = enc;
00205             if(get_audio_flags(enc)<0)
00206                 return -1;
00207         }
00208         avpriv_set_pts_info(s->streams[i], 32, 1, 1000); /* 32 bit pts in ms */
00209 
00210         sc = av_mallocz(sizeof(FLVStreamContext));
00211         if (!sc)
00212             return AVERROR(ENOMEM);
00213         s->streams[i]->priv_data = sc;
00214         sc->last_ts = -1;
00215     }
00216     flv->delay = AV_NOPTS_VALUE;
00217 
00218     avio_write(pb, "FLV", 3);
00219     avio_w8(pb,1);
00220     avio_w8(pb,   FLV_HEADER_FLAG_HASAUDIO * !!audio_enc
00221                  + FLV_HEADER_FLAG_HASVIDEO * !!video_enc);
00222     avio_wb32(pb,9);
00223     avio_wb32(pb,0);
00224 
00225     for(i=0; i<s->nb_streams; i++){
00226         if(s->streams[i]->codec->codec_tag == 5){
00227             avio_w8(pb,8); // message type
00228             avio_wb24(pb,0); // include flags
00229             avio_wb24(pb,0); // time stamp
00230             avio_wb32(pb,0); // reserved
00231             avio_wb32(pb,11); // size
00232             flv->reserved=5;
00233         }
00234     }
00235 
00236     /* write meta_tag */
00237     avio_w8(pb, 18);         // tag type META
00238     metadata_size_pos= avio_tell(pb);
00239     avio_wb24(pb, 0);          // size of data part (sum of all parts below)
00240     avio_wb24(pb, 0);          // time stamp
00241     avio_wb32(pb, 0);          // reserved
00242 
00243     /* now data of data_size size */
00244 
00245     /* first event name as a string */
00246     avio_w8(pb, AMF_DATA_TYPE_STRING);
00247     put_amf_string(pb, "onMetaData"); // 12 bytes
00248 
00249     /* mixed array (hash) with size and string/type/data tuples */
00250     avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY);
00251     metadata_count_pos = avio_tell(pb);
00252     metadata_count = 5*!!video_enc + 5*!!audio_enc + 2; // +2 for duration and file size
00253     avio_wb32(pb, metadata_count);
00254 
00255     put_amf_string(pb, "duration");
00256     flv->duration_offset= avio_tell(pb);
00257     put_amf_double(pb, s->duration / AV_TIME_BASE); // fill in the guessed duration, it'll be corrected later if incorrect
00258 
00259     if(video_enc){
00260         put_amf_string(pb, "width");
00261         put_amf_double(pb, video_enc->width);
00262 
00263         put_amf_string(pb, "height");
00264         put_amf_double(pb, video_enc->height);
00265 
00266         put_amf_string(pb, "videodatarate");
00267         put_amf_double(pb, video_enc->bit_rate / 1024.0);
00268 
00269         put_amf_string(pb, "framerate");
00270         put_amf_double(pb, framerate);
00271 
00272         put_amf_string(pb, "videocodecid");
00273         put_amf_double(pb, video_enc->codec_tag);
00274     }
00275 
00276     if(audio_enc){
00277         put_amf_string(pb, "audiodatarate");
00278         put_amf_double(pb, audio_enc->bit_rate / 1024.0);
00279 
00280         put_amf_string(pb, "audiosamplerate");
00281         put_amf_double(pb, audio_enc->sample_rate);
00282 
00283         put_amf_string(pb, "audiosamplesize");
00284         put_amf_double(pb, audio_enc->codec_id == CODEC_ID_PCM_U8 ? 8 : 16);
00285 
00286         put_amf_string(pb, "stereo");
00287         put_amf_bool(pb, audio_enc->channels == 2);
00288 
00289         put_amf_string(pb, "audiocodecid");
00290         put_amf_double(pb, audio_enc->codec_tag);
00291     }
00292 
00293     while ((tag = av_dict_get(s->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) {
00294         if(   !strcmp(tag->key, "width")
00295             ||!strcmp(tag->key, "height")
00296             ||!strcmp(tag->key, "videodatarate")
00297             ||!strcmp(tag->key, "framerate")
00298             ||!strcmp(tag->key, "videocodecid")
00299             ||!strcmp(tag->key, "audiodatarate")
00300             ||!strcmp(tag->key, "audiosamplerate")
00301             ||!strcmp(tag->key, "audiosamplesize")
00302             ||!strcmp(tag->key, "stereo")
00303             ||!strcmp(tag->key, "audiocodecid")
00304             ||!strcmp(tag->key, "duration")
00305             ||!strcmp(tag->key, "onMetaData")
00306         ){
00307             av_log(s, AV_LOG_DEBUG, "ignoring metadata for %s\n", tag->key);
00308             continue;
00309         }
00310         put_amf_string(pb, tag->key);
00311         avio_w8(pb, AMF_DATA_TYPE_STRING);
00312         put_amf_string(pb, tag->value);
00313         metadata_count++;
00314     }
00315 
00316     put_amf_string(pb, "filesize");
00317     flv->filesize_offset= avio_tell(pb);
00318     put_amf_double(pb, 0); // delayed write
00319 
00320     put_amf_string(pb, "");
00321     avio_w8(pb, AMF_END_OF_OBJECT);
00322 
00323     /* write total size of tag */
00324     data_size= avio_tell(pb) - metadata_size_pos - 10;
00325 
00326     avio_seek(pb, metadata_count_pos, SEEK_SET);
00327     avio_wb32(pb, metadata_count);
00328 
00329     avio_seek(pb, metadata_size_pos, SEEK_SET);
00330     avio_wb24(pb, data_size);
00331     avio_skip(pb, data_size + 10 - 3);
00332     avio_wb32(pb, data_size + 11);
00333 
00334     for (i = 0; i < s->nb_streams; i++) {
00335         AVCodecContext *enc = s->streams[i]->codec;
00336         if (enc->codec_id == CODEC_ID_AAC || enc->codec_id == CODEC_ID_H264 || enc->codec_id == CODEC_ID_MPEG4) {
00337             int64_t pos;
00338             avio_w8(pb, enc->codec_type == AVMEDIA_TYPE_VIDEO ?
00339                      FLV_TAG_TYPE_VIDEO : FLV_TAG_TYPE_AUDIO);
00340             avio_wb24(pb, 0); // size patched later
00341             avio_wb24(pb, 0); // ts
00342             avio_w8(pb, 0); // ts ext
00343             avio_wb24(pb, 0); // streamid
00344             pos = avio_tell(pb);
00345             if (enc->codec_id == CODEC_ID_AAC) {
00346                 avio_w8(pb, get_audio_flags(enc));
00347                 avio_w8(pb, 0); // AAC sequence header
00348                 avio_write(pb, enc->extradata, enc->extradata_size);
00349             } else {
00350                 avio_w8(pb, enc->codec_tag | FLV_FRAME_KEY); // flags
00351                 avio_w8(pb, 0); // AVC sequence header
00352                 avio_wb24(pb, 0); // composition time
00353                 ff_isom_write_avcc(pb, enc->extradata, enc->extradata_size);
00354             }
00355             data_size = avio_tell(pb) - pos;
00356             avio_seek(pb, -data_size - 10, SEEK_CUR);
00357             avio_wb24(pb, data_size);
00358             avio_skip(pb, data_size + 10 - 3);
00359             avio_wb32(pb, data_size + 11); // previous tag size
00360         }
00361     }
00362 
00363     return 0;
00364 }
00365 
00366 static int flv_write_trailer(AVFormatContext *s)
00367 {
00368     int64_t file_size;
00369 
00370     AVIOContext *pb = s->pb;
00371     FLVContext *flv = s->priv_data;
00372     int i;
00373 
00374     /* Add EOS tag */
00375     for (i = 0; i < s->nb_streams; i++) {
00376         AVCodecContext *enc = s->streams[i]->codec;
00377         FLVStreamContext *sc = s->streams[i]->priv_data;
00378         if (enc->codec_type == AVMEDIA_TYPE_VIDEO &&
00379                 (enc->codec_id == CODEC_ID_H264 || enc->codec_id == CODEC_ID_MPEG4)) {
00380             put_avc_eos_tag(pb, sc->last_ts);
00381         }
00382     }
00383 
00384     file_size = avio_tell(pb);
00385 
00386     /* update informations */
00387     avio_seek(pb, flv->duration_offset, SEEK_SET);
00388     put_amf_double(pb, flv->duration / (double)1000);
00389     avio_seek(pb, flv->filesize_offset, SEEK_SET);
00390     put_amf_double(pb, file_size);
00391 
00392     avio_seek(pb, file_size, SEEK_SET);
00393     return 0;
00394 }
00395 
00396 static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
00397 {
00398     AVIOContext *pb = s->pb;
00399     AVCodecContext *enc = s->streams[pkt->stream_index]->codec;
00400     FLVContext *flv = s->priv_data;
00401     FLVStreamContext *sc = s->streams[pkt->stream_index]->priv_data;
00402     unsigned ts;
00403     int size= pkt->size;
00404     uint8_t *data= NULL;
00405     int flags, flags_size;
00406 
00407 //    av_log(s, AV_LOG_DEBUG, "type:%d pts: %"PRId64" size:%d\n", enc->codec_type, timestamp, size);
00408 
00409     if(enc->codec_id == CODEC_ID_VP6 || enc->codec_id == CODEC_ID_VP6F ||
00410        enc->codec_id == CODEC_ID_AAC)
00411         flags_size= 2;
00412     else if(enc->codec_id == CODEC_ID_H264 || enc->codec_id == CODEC_ID_MPEG4)
00413         flags_size= 5;
00414     else
00415         flags_size= 1;
00416 
00417     if (enc->codec_type == AVMEDIA_TYPE_VIDEO) {
00418         avio_w8(pb, FLV_TAG_TYPE_VIDEO);
00419 
00420         flags = enc->codec_tag;
00421         if(flags == 0) {
00422             av_log(enc, AV_LOG_ERROR, "video codec %s not compatible with flv\n", avcodec_get_name(enc->codec_id));
00423             return -1;
00424         }
00425 
00426         flags |= pkt->flags & AV_PKT_FLAG_KEY ? FLV_FRAME_KEY : FLV_FRAME_INTER;
00427     } else if (enc->codec_type == AVMEDIA_TYPE_AUDIO) {
00428         flags = get_audio_flags(enc);
00429 
00430         assert(size);
00431 
00432         avio_w8(pb, FLV_TAG_TYPE_AUDIO);
00433     } else {
00434         // In-band flv metadata ("scriptdata")
00435         assert(enc->codec_type == AVMEDIA_TYPE_DATA);
00436         avio_w8(pb, FLV_TAG_TYPE_META);
00437         flags_size = 0;
00438         flags = 0;
00439     }
00440 
00441     if (enc->codec_id == CODEC_ID_H264 || enc->codec_id == CODEC_ID_MPEG4) {
00442         /* check if extradata looks like mp4 formated */
00443         if (enc->extradata_size > 0 && *(uint8_t*)enc->extradata != 1) {
00444             if (ff_avc_parse_nal_units_buf(pkt->data, &data, &size) < 0)
00445                 return -1;
00446         }
00447     } else if (enc->codec_id == CODEC_ID_AAC && pkt->size > 2 &&
00448                (AV_RB16(pkt->data) & 0xfff0) == 0xfff0) {
00449         av_log(s, AV_LOG_ERROR, "malformated aac bitstream, use -absf aac_adtstoasc\n");
00450         return -1;
00451     }
00452     if (flv->delay == AV_NOPTS_VALUE)
00453         flv->delay = -pkt->dts;
00454     if (pkt->dts < -flv->delay) {
00455         av_log(s, AV_LOG_WARNING, "Packets are not in the proper order with "
00456                                   "respect to DTS\n");
00457         return AVERROR(EINVAL);
00458     }
00459 
00460     ts = pkt->dts + flv->delay; // add delay to force positive dts
00461 
00462     /* check Speex packet duration */
00463     if (enc->codec_id == CODEC_ID_SPEEX && ts - sc->last_ts > 160) {
00464         av_log(s, AV_LOG_WARNING, "Warning: Speex stream has more than "
00465                                   "8 frames per packet. Adobe Flash "
00466                                   "Player cannot handle this!\n");
00467     }
00468 
00469     if (sc->last_ts < ts)
00470         sc->last_ts = ts;
00471 
00472     avio_wb24(pb,size + flags_size);
00473     avio_wb24(pb,ts);
00474     avio_w8(pb,(ts >> 24) & 0x7F); // timestamps are 32bits _signed_
00475     avio_wb24(pb,flv->reserved);
00476 
00477     if(flags_size)
00478         avio_w8(pb,flags);
00479 
00480     if (enc->codec_id == CODEC_ID_VP6)
00481         avio_w8(pb,0);
00482     if (enc->codec_id == CODEC_ID_VP6F)
00483         avio_w8(pb, enc->extradata_size ? enc->extradata[0] : 0);
00484     else if (enc->codec_id == CODEC_ID_AAC)
00485         avio_w8(pb,1); // AAC raw
00486     else if (enc->codec_id == CODEC_ID_H264 || enc->codec_id == CODEC_ID_MPEG4) {
00487         avio_w8(pb,1); // AVC NALU
00488         avio_wb24(pb,pkt->pts - pkt->dts);
00489     }
00490 
00491     avio_write(pb, data ? data : pkt->data, size);
00492 
00493     avio_wb32(pb,size+flags_size+11); // previous tag size
00494     flv->duration = FFMAX(flv->duration, pkt->pts + flv->delay + pkt->duration);
00495 
00496     avio_flush(pb);
00497 
00498     av_free(data);
00499 
00500     return pb->error;
00501 }
00502 
00503 AVOutputFormat ff_flv_muxer = {
00504     .name           = "flv",
00505     .long_name      = NULL_IF_CONFIG_SMALL("FLV format"),
00506     .mime_type      = "video/x-flv",
00507     .extensions     = "flv",
00508     .priv_data_size = sizeof(FLVContext),
00509 #if CONFIG_LIBMP3LAME
00510     .audio_codec    = CODEC_ID_MP3,
00511 #else // CONFIG_LIBMP3LAME
00512     .audio_codec    = CODEC_ID_ADPCM_SWF,
00513 #endif // CONFIG_LIBMP3LAME
00514     .video_codec    = CODEC_ID_FLV1,
00515     .write_header   = flv_write_header,
00516     .write_packet   = flv_write_packet,
00517     .write_trailer  = flv_write_trailer,
00518     .codec_tag= (const AVCodecTag* const []){flv_video_codec_ids, flv_audio_codec_ids, 0},
00519     .flags= AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS,
00520 };