libavformat/flvenc.c

   1 /*
   2  * FLV muxer
   3  * Copyright (c) 2003 The Libav Project
   4  *
   5  * This file is part of Libav.
   6  *
   7  * Libav is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; either
  10  * version 2.1 of the License, or (at your option) any later version.
  11  *
  12  * Libav is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with Libav; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #include "libavutil/dict.h"
  23 #include "libavutil/intfloat.h"
  24 #include "avc.h"
  25 #include "avformat.h"
  26 #include "flv.h"
  27 #include "internal.h"
  28 #include "metadata.h"
  29
  30 #undef NDEBUG
  31 #include <assert.h>
  32
  33 static const AVCodecTag flv_video_codec_ids[] = {
  34     { AV_CODEC_ID_FLV1,     FLV_CODECID_H263 },
  35     { AV_CODEC_ID_FLASHSV,  FLV_CODECID_SCREEN },
  36     { AV_CODEC_ID_FLASHSV2, FLV_CODECID_SCREEN2 },
  37     { AV_CODEC_ID_VP6F,     FLV_CODECID_VP6 },
  38     { AV_CODEC_ID_VP6A,     FLV_CODECID_VP6A },
  39     { AV_CODEC_ID_H264,     FLV_CODECID_H264 },
  40     { AV_CODEC_ID_NONE,     0 }
  41 };
  42
  43 static const AVCodecTag flv_audio_codec_ids[] = {
  44     { AV_CODEC_ID_MP3,        FLV_CODECID_MP3        >> FLV_AUDIO_CODECID_OFFSET },
  45     { AV_CODEC_ID_PCM_U8,     FLV_CODECID_PCM        >> FLV_AUDIO_CODECID_OFFSET },
  46     { AV_CODEC_ID_PCM_S16BE,  FLV_CODECID_PCM        >> FLV_AUDIO_CODECID_OFFSET },
  47     { AV_CODEC_ID_PCM_S16LE,  FLV_CODECID_PCM_LE     >> FLV_AUDIO_CODECID_OFFSET },
  48     { AV_CODEC_ID_ADPCM_SWF,  FLV_CODECID_ADPCM      >> FLV_AUDIO_CODECID_OFFSET },
  49     { AV_CODEC_ID_AAC,        FLV_CODECID_AAC        >> FLV_AUDIO_CODECID_OFFSET },
  50     { AV_CODEC_ID_NELLYMOSER, FLV_CODECID_NELLYMOSER >> FLV_AUDIO_CODECID_OFFSET },
  51     { AV_CODEC_ID_PCM_MULAW,  FLV_CODECID_PCM_MULAW  >> FLV_AUDIO_CODECID_OFFSET },
  52     { AV_CODEC_ID_PCM_ALAW,   FLV_CODECID_PCM_ALAW   >> FLV_AUDIO_CODECID_OFFSET },
  53     { AV_CODEC_ID_SPEEX,      FLV_CODECID_SPEEX      >> FLV_AUDIO_CODECID_OFFSET },
  54     { AV_CODEC_ID_NONE,       0 }
  55 };
  56
  57 typedef struct FLVContext {
  58     int     reserved;
  59     int64_t duration_offset;
  60     int64_t filesize_offset;
  61     int64_t duration;
  62     int64_t delay;      ///< first dts delay (needed for AVC & Speex)
  63
  64     AVCodecContext *audio_enc;
  65     AVCodecContext *video_enc;
  66     double framerate;
  67     AVCodecContext *data_enc;
  68 } FLVContext;
  69
  70 typedef struct FLVStreamContext {
  71     int64_t last_ts;    ///< last timestamp for each stream
  72 } FLVStreamContext;
  73
  74 static int get_audio_flags(AVFormatContext *s, AVCodecContext *enc)
  75 {
  76     int flags = (enc->bits_per_coded_sample == 16) ? FLV_SAMPLESSIZE_16BIT
  77                                                    : FLV_SAMPLESSIZE_8BIT;
  78
  79     if (enc->codec_id == AV_CODEC_ID_AAC) // specs force these parameters
  80         return FLV_CODECID_AAC | FLV_SAMPLERATE_44100HZ |
  81                FLV_SAMPLESSIZE_16BIT | FLV_STEREO;
  82     else if (enc->codec_id == AV_CODEC_ID_SPEEX) {
  83         if (enc->sample_rate != 16000) {
  84             av_log(s, AV_LOG_ERROR,
  85                    "flv only supports wideband (16kHz) Speex audio\n");
  86             return -1;
  87         }
  88         if (enc->channels != 1) {
  89             av_log(s, AV_LOG_ERROR, "flv only supports mono Speex audio\n");
  90             return -1;
  91         }
  92         return FLV_CODECID_SPEEX | FLV_SAMPLERATE_11025HZ | FLV_SAMPLESSIZE_16BIT;
  93     } else {
  94         switch (enc->sample_rate) {
  95         case 44100:
  96             flags |= FLV_SAMPLERATE_44100HZ;
  97             break;
  98         case 22050:
  99             flags |= FLV_SAMPLERATE_22050HZ;
 100             break;
 101         case 11025:
 102             flags |= FLV_SAMPLERATE_11025HZ;
 103             break;
 104         case 16000: // nellymoser only
 105         case  8000: // nellymoser only
 106         case  5512: // not MP3
 107             if (enc->codec_id != AV_CODEC_ID_MP3) {
 108                 flags |= FLV_SAMPLERATE_SPECIAL;
 109                 break;
 110             }
 111         default:
 112             av_log(s, AV_LOG_ERROR,
 113                    "flv does not support that sample rate, "
 114                    "choose from (44100, 22050, 11025).\n");
 115             return -1;
 116         }
 117     }
 118
 119     if (enc->channels > 1)
 120         flags |= FLV_STEREO;
 121
 122     switch (enc->codec_id) {
 123     case AV_CODEC_ID_MP3:
 124         flags |= FLV_CODECID_MP3    | FLV_SAMPLESSIZE_16BIT;
 125         break;
 126     case AV_CODEC_ID_PCM_U8:
 127         flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_8BIT;
 128         break;
 129     case AV_CODEC_ID_PCM_S16BE:
 130         flags |= FLV_CODECID_PCM    | FLV_SAMPLESSIZE_16BIT;
 131         break;
 132     case AV_CODEC_ID_PCM_S16LE:
 133         flags |= FLV_CODECID_PCM_LE | FLV_SAMPLESSIZE_16BIT;
 134         break;
 135     case AV_CODEC_ID_ADPCM_SWF:
 136         flags |= FLV_CODECID_ADPCM  | FLV_SAMPLESSIZE_16BIT;
 137         break;
 138     case AV_CODEC_ID_NELLYMOSER:
 139         if (enc->sample_rate == 8000)
 140             flags |= FLV_CODECID_NELLYMOSER_8KHZ_MONO  | FLV_SAMPLESSIZE_16BIT;
 141         else if (enc->sample_rate == 16000)
 142             flags |= FLV_CODECID_NELLYMOSER_16KHZ_MONO | FLV_SAMPLESSIZE_16BIT;
 143         else
 144             flags |= FLV_CODECID_NELLYMOSER            | FLV_SAMPLESSIZE_16BIT;
 145         break;
 146     case AV_CODEC_ID_PCM_MULAW:
 147         flags = FLV_CODECID_PCM_MULAW | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT;
 148         break;
 149     case AV_CODEC_ID_PCM_ALAW:
 150         flags = FLV_CODECID_PCM_ALAW  | FLV_SAMPLERATE_SPECIAL | FLV_SAMPLESSIZE_16BIT;
 151         break;
 152     case 0:
 153         flags |= enc->codec_tag << 4;
 154         break;
 155     default:
 156         av_log(s, AV_LOG_ERROR, "codec not compatible with flv\n");
 157         return -1;
 158     }
 159
 160     return flags;
 161 }
 162
 163 static void put_amf_string(AVIOContext *pb, const char *str)
 164 {
 165     size_t len = strlen(str);
 166     avio_wb16(pb, len);
 167     avio_write(pb, str, len);
 168 }
 169
 170 static void put_avc_eos_tag(AVIOContext *pb, unsigned ts)
 171 {
 172     avio_w8(pb, FLV_TAG_TYPE_VIDEO);
 173     avio_wb24(pb, 5);               /* Tag Data Size */
 174     avio_wb24(pb, ts);              /* lower 24 bits of timestamp in ms */
 175     avio_w8(pb, (ts >> 24) & 0x7F); /* MSB of ts in ms */
 176     avio_wb24(pb, 0);               /* StreamId = 0 */
 177     avio_w8(pb, 23);                /* ub[4] FrameType = 1, ub[4] CodecId = 7 */
 178     avio_w8(pb, 2);                 /* AVC end of sequence */
 179     avio_wb24(pb, 0);               /* Always 0 for AVC EOS. */
 180     avio_wb32(pb, 16);              /* Size of FLV tag */
 181 }
 182
 183 static void put_amf_double(AVIOContext *pb, double d)
 184 {
 185     avio_w8(pb, AMF_DATA_TYPE_NUMBER);
 186     avio_wb64(pb, av_double2int(d));
 187 }
 188
 189 static void put_amf_bool(AVIOContext *pb, int b)
 190 {
 191     avio_w8(pb, AMF_DATA_TYPE_BOOL);
 192     avio_w8(pb, !!b);
 193 }
 194
 195 static void write_metadata(AVFormatContext *s, unsigned int ts)
 196 {
 197     AVIOContext *pb = s->pb;
 198     FLVContext *flv = s->priv_data;
 199     int metadata_count = 0;
 200     int64_t metadata_size_pos, data_size, metadata_count_pos;
 201     AVDictionaryEntry *tag = NULL;
 202
 203     /* write meta_tag */
 204     avio_w8(pb, 18);            // tag type META
 205     metadata_size_pos = avio_tell(pb);
 206     avio_wb24(pb, 0);           // size of data part (sum of all parts below)
 207     avio_wb24(pb, ts);          // timestamp
 208     avio_wb32(pb, 0);           // reserved
 209
 210     /* now data of data_size size */
 211
 212     /* first event name as a string */
 213     avio_w8(pb, AMF_DATA_TYPE_STRING);
 214     put_amf_string(pb, "onMetaData"); // 12 bytes
 215
 216     /* mixed array (hash) with size and string/type/data tuples */
 217     avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY);
 218     metadata_count_pos = avio_tell(pb);
 219     metadata_count = 4 * !!flv->video_enc +
 220                      5 * !!flv->audio_enc +
 221                      1 * !!flv->data_enc  +
 222                      2; // +2 for duration and file size
 223
 224     avio_wb32(pb, metadata_count);
 225
 226     put_amf_string(pb, "duration");
 227     flv->duration_offset = avio_tell(pb);
 228
 229     // fill in the guessed duration, it'll be corrected later if incorrect
 230     put_amf_double(pb, s->duration / AV_TIME_BASE);
 231
 232     if (flv->video_enc) {
 233         put_amf_string(pb, "width");
 234         put_amf_double(pb, flv->video_enc->width);
 235
 236         put_amf_string(pb, "height");
 237         put_amf_double(pb, flv->video_enc->height);
 238
 239         put_amf_string(pb, "videodatarate");
 240         put_amf_double(pb, flv->video_enc->bit_rate / 1024.0);
 241
 242         if (flv->framerate != 0.0) {
 243             put_amf_string(pb, "framerate");
 244             put_amf_double(pb, flv->framerate);
 245             metadata_count++;
 246         }
 247
 248         put_amf_string(pb, "videocodecid");
 249         put_amf_double(pb, flv->video_enc->codec_tag);
 250     }
 251
 252     if (flv->audio_enc) {
 253         put_amf_string(pb, "audiodatarate");
 254         put_amf_double(pb, flv->audio_enc->bit_rate / 1024.0);
 255
 256         put_amf_string(pb, "audiosamplerate");
 257         put_amf_double(pb, flv->audio_enc->sample_rate);
 258
 259         put_amf_string(pb, "audiosamplesize");
 260         put_amf_double(pb, flv->audio_enc->codec_id == AV_CODEC_ID_PCM_U8 ? 8 : 16);
 261
 262         put_amf_string(pb, "stereo");
 263         put_amf_bool(pb, flv->audio_enc->channels == 2);
 264
 265         put_amf_string(pb, "audiocodecid");
 266         put_amf_double(pb, flv->audio_enc->codec_tag);
 267     }
 268
 269     if (flv->data_enc) {
 270         put_amf_string(pb, "datastream");
 271         put_amf_double(pb, 0.0);
 272     }
 273
 274     while ((tag = av_dict_get(s->metadata, "", tag, AV_DICT_IGNORE_SUFFIX))) {
 275         put_amf_string(pb, tag->key);
 276         avio_w8(pb, AMF_DATA_TYPE_STRING);
 277         put_amf_string(pb, tag->value);
 278         metadata_count++;
 279     }
 280
 281     put_amf_string(pb, "filesize");
 282     flv->filesize_offset = avio_tell(pb);
 283     put_amf_double(pb, 0); // delayed write
 284
 285     put_amf_string(pb, "");
 286     avio_w8(pb, AMF_END_OF_OBJECT);
 287
 288     /* write total size of tag */
 289     data_size = avio_tell(pb) - metadata_size_pos - 10;
 290
 291     avio_seek(pb, metadata_count_pos, SEEK_SET);
 292     avio_wb32(pb, metadata_count);
 293
 294     avio_seek(pb, metadata_size_pos, SEEK_SET);
 295     avio_wb24(pb, data_size);
 296     avio_skip(pb, data_size + 10 - 3);
 297     avio_wb32(pb, data_size + 11);
 298 }
 299
 300 static int unsupported_codec(AVFormatContext *s,
 301                              const char* type, int codec_id)
 302 {
 303     const AVCodecDescriptor *desc = avcodec_descriptor_get(codec_id);
 304     av_log(s, AV_LOG_ERROR,
 305            "%s codec %s not compatible with flv\n",
 306             type,
 307             desc ? desc->name : "unknown");
 308     return AVERROR(ENOSYS);
 309 }
 310
 311 static int flv_write_header(AVFormatContext *s)
 312 {
 313     int i;
 314     AVIOContext *pb = s->pb;
 315     FLVContext *flv = s->priv_data;
 316     int64_t data_size;
 317
 318     for (i = 0; i < s->nb_streams; i++) {
 319         AVCodecContext *enc = s->streams[i]->codec;
 320         FLVStreamContext *sc;
 321         switch (enc->codec_type) {
 322         case AVMEDIA_TYPE_VIDEO:
 323             if (s->streams[i]->avg_frame_rate.den &&
 324                 s->streams[i]->avg_frame_rate.num) {
 325                 flv->framerate = av_q2d(s->streams[i]->avg_frame_rate);
 326             }
 327             if (flv->video_enc) {
 328                 av_log(s, AV_LOG_ERROR,
 329                        "at most one video stream is supported in flv\n");
 330                 return AVERROR(EINVAL);
 331             }
 332             flv->video_enc = enc;
 333             if (!ff_codec_get_tag(flv_video_codec_ids, enc->codec_id))
 334                 return unsupported_codec(s, "Video", enc->codec_id);
 335             break;
 336         case AVMEDIA_TYPE_AUDIO:
 337             if (flv->audio_enc) {
 338                 av_log(s, AV_LOG_ERROR,
 339                        "at most one audio stream is supported in flv\n");
 340                 return AVERROR(EINVAL);
 341             }
 342             flv->audio_enc = enc;
 343             if (get_audio_flags(s, enc) < 0)
 344                 return unsupported_codec(s, "Audio", enc->codec_id);
 345             break;
 346         case AVMEDIA_TYPE_DATA:
 347             if (enc->codec_id != AV_CODEC_ID_TEXT)
 348                 return unsupported_codec(s, "Data", enc->codec_id);
 349             flv->data_enc = enc;
 350             break;
 351         default:
 352             av_log(s, AV_LOG_ERROR, "codec not compatible with flv\n");
 353             return -1;
 354         }
 355         avpriv_set_pts_info(s->streams[i], 32, 1, 1000); /* 32 bit pts in ms */
 356
 357         sc = av_mallocz(sizeof(FLVStreamContext));
 358         if (!sc)
 359             return AVERROR(ENOMEM);
 360         s->streams[i]->priv_data = sc;
 361         sc->last_ts = -1;
 362     }
 363
 364     flv->delay = AV_NOPTS_VALUE;
 365
 366     avio_write(pb, "FLV", 3);
 367     avio_w8(pb, 1);
 368     avio_w8(pb, FLV_HEADER_FLAG_HASAUDIO * !!flv->audio_enc +
 369                 FLV_HEADER_FLAG_HASVIDEO * !!flv->video_enc);
 370     avio_wb32(pb, 9);
 371     avio_wb32(pb, 0);
 372
 373     for (i = 0; i < s->nb_streams; i++)
 374         if (s->streams[i]->codec->codec_tag == 5) {
 375             avio_w8(pb, 8);     // message type
 376             avio_wb24(pb, 0);   // include flags
 377             avio_wb24(pb, 0);   // time stamp
 378             avio_wb32(pb, 0);   // reserved
 379             avio_wb32(pb, 11);  // size
 380             flv->reserved = 5;
 381         }
 382
 383     write_metadata(s, 0);
 384
 385     for (i = 0; i < s->nb_streams; i++) {
 386         AVCodecContext *enc = s->streams[i]->codec;
 387         if (enc->codec_id == AV_CODEC_ID_AAC || enc->codec_id == AV_CODEC_ID_H264) {
 388             int64_t pos;
 389             avio_w8(pb, enc->codec_type == AVMEDIA_TYPE_VIDEO ?
 390                     FLV_TAG_TYPE_VIDEO : FLV_TAG_TYPE_AUDIO);
 391             avio_wb24(pb, 0); // size patched later
 392             avio_wb24(pb, 0); // ts
 393             avio_w8(pb, 0);   // ts ext
 394             avio_wb24(pb, 0); // streamid
 395             pos = avio_tell(pb);
 396             if (enc->codec_id == AV_CODEC_ID_AAC) {
 397                 avio_w8(pb, get_audio_flags(s, enc));
 398                 avio_w8(pb, 0); // AAC sequence header
 399                 avio_write(pb, enc->extradata, enc->extradata_size);
 400             } else {
 401                 avio_w8(pb, enc->codec_tag | FLV_FRAME_KEY); // flags
 402                 avio_w8(pb, 0); // AVC sequence header
 403                 avio_wb24(pb, 0); // composition time
 404                 ff_isom_write_avcc(pb, enc->extradata, enc->extradata_size);
 405             }
 406             data_size = avio_tell(pb) - pos;
 407             avio_seek(pb, -data_size - 10, SEEK_CUR);
 408             avio_wb24(pb, data_size);
 409             avio_skip(pb, data_size + 10 - 3);
 410             avio_wb32(pb, data_size + 11); // previous tag size
 411         }
 412     }
 413
 414     return 0;
 415 }
 416
 417 static int flv_write_trailer(AVFormatContext *s)
 418 {
 419     int64_t file_size;
 420
 421     AVIOContext *pb = s->pb;
 422     FLVContext *flv = s->priv_data;
 423     int i;
 424
 425     /* Add EOS tag */
 426     for (i = 0; i < s->nb_streams; i++) {
 427         AVCodecContext *enc = s->streams[i]->codec;
 428         FLVStreamContext *sc = s->streams[i]->priv_data;
 429         if (enc->codec_type == AVMEDIA_TYPE_VIDEO &&
 430             enc->codec_id == AV_CODEC_ID_H264)
 431             put_avc_eos_tag(pb, sc->last_ts);
 432     }
 433
 434     file_size = avio_tell(pb);
 435
 436     /* update information */
 437     if (avio_seek(pb, flv->duration_offset, SEEK_SET) < 0)
 438         av_log(s, AV_LOG_WARNING, "Failed to update header with correct duration.\n");
 439     else
 440         put_amf_double(pb, flv->duration / (double)1000);
 441     if (avio_seek(pb, flv->filesize_offset, SEEK_SET) < 0)
 442         av_log(s, AV_LOG_WARNING, "Failed to update header with correct filesize.\n");
 443     else
 444         put_amf_double(pb, file_size);
 445
 446     avio_seek(pb, file_size, SEEK_SET);
 447     return 0;
 448 }
 449
 450 static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
 451 {
 452     AVIOContext *pb      = s->pb;
 453     AVCodecContext *enc  = s->streams[pkt->stream_index]->codec;
 454     FLVContext *flv      = s->priv_data;
 455     FLVStreamContext *sc = s->streams[pkt->stream_index]->priv_data;
 456     unsigned ts;
 457     int size = pkt->size;
 458     uint8_t *data = NULL;
 459     int flags = 0, flags_size;
 460
 461     if (enc->codec_id == AV_CODEC_ID_VP6F || enc->codec_id == AV_CODEC_ID_VP6A ||
 462         enc->codec_id == AV_CODEC_ID_AAC)
 463         flags_size = 2;
 464     else if (enc->codec_id == AV_CODEC_ID_H264)
 465         flags_size = 5;
 466     else
 467         flags_size = 1;
 468
 469     if (flv->delay == AV_NOPTS_VALUE)
 470         flv->delay = -pkt->dts;
 471
 472     if (pkt->dts < -flv->delay) {
 473         av_log(s, AV_LOG_WARNING,
 474                "Packets are not in the proper order with respect to DTS\n");
 475         return AVERROR(EINVAL);
 476     }
 477
 478     ts = pkt->dts + flv->delay; // add delay to force positive dts
 479
 480     if (s->event_flags & AVSTREAM_EVENT_FLAG_METADATA_UPDATED) {
 481         write_metadata(s, ts);
 482         s->event_flags &= ~AVSTREAM_EVENT_FLAG_METADATA_UPDATED;
 483     }
 484
 485     switch (enc->codec_type) {
 486     case AVMEDIA_TYPE_VIDEO:
 487         avio_w8(pb, FLV_TAG_TYPE_VIDEO);
 488
 489         flags = ff_codec_get_tag(flv_video_codec_ids, enc->codec_id);
 490
 491         flags |= pkt->flags & AV_PKT_FLAG_KEY ? FLV_FRAME_KEY : FLV_FRAME_INTER;
 492         break;
 493     case AVMEDIA_TYPE_AUDIO:
 494         flags = get_audio_flags(s, enc);
 495
 496         assert(size);
 497
 498         avio_w8(pb, FLV_TAG_TYPE_AUDIO);
 499         break;
 500     case AVMEDIA_TYPE_DATA:
 501         avio_w8(pb, FLV_TAG_TYPE_META);
 502         break;
 503     default:
 504         return AVERROR(EINVAL);
 505     }
 506
 507     if (enc->codec_id == AV_CODEC_ID_H264)
 508         /* check if extradata looks like MP4 */
 509         if (enc->extradata_size > 0 && *(uint8_t*)enc->extradata != 1)
 510             if (ff_avc_parse_nal_units_buf(pkt->data, &data, &size) < 0)
 511                 return -1;
 512
 513     /* check Speex packet duration */
 514     if (enc->codec_id == AV_CODEC_ID_SPEEX && ts - sc->last_ts > 160)
 515         av_log(s, AV_LOG_WARNING, "Warning: Speex stream has more than "
 516                                   "8 frames per packet. Adobe Flash "
 517                                   "Player cannot handle this!\n");
 518
 519     if (sc->last_ts < ts)
 520         sc->last_ts = ts;
 521
 522     avio_wb24(pb, size + flags_size);
 523     avio_wb24(pb, ts);
 524     avio_w8(pb, (ts >> 24) & 0x7F); // timestamps are 32 bits _signed_
 525     avio_wb24(pb, flv->reserved);
 526
 527     if (enc->codec_type == AVMEDIA_TYPE_DATA) {
 528         int data_size;
 529         int64_t metadata_size_pos = avio_tell(pb);
 530         avio_w8(pb, AMF_DATA_TYPE_STRING);
 531         put_amf_string(pb, "onTextData");
 532         avio_w8(pb, AMF_DATA_TYPE_MIXEDARRAY);
 533         avio_wb32(pb, 2);
 534         put_amf_string(pb, "type");
 535         avio_w8(pb, AMF_DATA_TYPE_STRING);
 536         put_amf_string(pb, "Text");
 537         put_amf_string(pb, "text");
 538         avio_w8(pb, AMF_DATA_TYPE_STRING);
 539         put_amf_string(pb, pkt->data);
 540         put_amf_string(pb, "");
 541         avio_w8(pb, AMF_END_OF_OBJECT);
 542         /* write total size of tag */
 543         data_size = avio_tell(pb) - metadata_size_pos;
 544         avio_seek(pb, metadata_size_pos - 10, SEEK_SET);
 545         avio_wb24(pb, data_size);
 546         avio_seek(pb, data_size + 10 - 3, SEEK_CUR);
 547         avio_wb32(pb, data_size + 11);
 548     } else {
 549         avio_w8(pb,flags);
 550         if (enc->codec_id == AV_CODEC_ID_VP6F || enc->codec_id == AV_CODEC_ID_VP6A) {
 551             if (enc->extradata_size)
 552                 avio_w8(pb, enc->extradata[0]);
 553             else
 554                 avio_w8(pb, ((FFALIGN(enc->width,  16) - enc->width) << 4) |
 555                              (FFALIGN(enc->height, 16) - enc->height));
 556         } else if (enc->codec_id == AV_CODEC_ID_AAC)
 557             avio_w8(pb, 1); // AAC raw
 558         else if (enc->codec_id == AV_CODEC_ID_H264) {
 559             avio_w8(pb, 1); // AVC NALU
 560             avio_wb24(pb, pkt->pts - pkt->dts);
 561         }
 562
 563         avio_write(pb, data ? data : pkt->data, size);
 564
 565         avio_wb32(pb, size + flags_size + 11); // previous tag size
 566         flv->duration = FFMAX(flv->duration,
 567                               pkt->pts + flv->delay + pkt->duration);
 568     }
 569
 570     av_free(data);
 571
 572     return pb->error;
 573 }
 574
 575 AVOutputFormat ff_flv_muxer = {
 576     .name           = "flv",
 577     .long_name      = NULL_IF_CONFIG_SMALL("FLV (Flash Video)"),
 578     .mime_type      = "video/x-flv",
 579     .extensions     = "flv",
 580     .priv_data_size = sizeof(FLVContext),
 581     .audio_codec    = CONFIG_LIBMP3LAME ? AV_CODEC_ID_MP3 : AV_CODEC_ID_ADPCM_SWF,
 582     .video_codec    = AV_CODEC_ID_FLV1,
 583     .write_header   = flv_write_header,
 584     .write_packet   = flv_write_packet,
 585     .write_trailer  = flv_write_trailer,
 586     .codec_tag      = (const AVCodecTag* const []) {
 587                           flv_video_codec_ids, flv_audio_codec_ids, 0
 588                       },
 589     .flags          = AVFMT_GLOBALHEADER | AVFMT_VARIABLE_FPS |
 590                       AVFMT_TS_NONSTRICT,
 591 };