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FFmpeg/libavformat/flvdec.c

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  1. /*

  2.  * FLV demuxer

  3.  * Copyright (c) 2003 The FFmpeg Project

  4.  *

  5.  * This demuxer will generate a 1 byte extradata for VP6F content.

  6.  * It is composed of:

  7.  *  - upper 4bits: difference between encoded width and visible width

  8.  *  - lower 4bits: difference between encoded height and visible height

  9.  *

  10.  * This file is part of FFmpeg.

  11.  *

  12.  * FFmpeg is free software; you can redistribute it and/or

  13.  * modify it under the terms of the GNU Lesser General Public

  14.  * License as published by the Free Software Foundation; either

  15.  * version 2.1 of the License, or (at your option) any later version.

  16.  *

  17.  * FFmpeg is distributed in the hope that it will be useful,

  18.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  19.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  20.  * Lesser General Public License for more details.

  21.  *

  22.  * You should have received a copy of the GNU Lesser General Public

  23.  * License along with FFmpeg; if not, write to the Free Software

  24.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  25.  */

  26. 

  27. #include "libavutil/avstring.h"

  28. #include "libavutil/dict.h"

  29. #include "libavutil/intfloat_readwrite.h"

  30. #include "libavutil/mathematics.h"

  31. #include "libavcodec/bytestream.h"

  32. #include "libavcodec/mpeg4audio.h"

  33. #include "avformat.h"

  34. #include "avio_internal.h"

  35. #include "flv.h"

  36. 

  37. typedef struct {

  38.     int wrong_dts; ///< wrong dts due to negative cts

  39. } FLVContext;

  40. 

  41. static int flv_probe(AVProbeData *p)

  42. {

  43.     const uint8_t *d;

  44. 

  45.     d = p->buf;

  46.     if (d[0] == 'F' && d[1] == 'L' && d[2] == 'V' && d[3] < 5 && d[5]==0 && AV_RB32(d+5)>8) {

  47.         return AVPROBE_SCORE_MAX;

  48.     }

  49.     return 0;

  50. }

  51. 

  52. static void flv_set_audio_codec(AVFormatContext *s, AVStream *astream, int flv_codecid) {

  53.     AVCodecContext *acodec = astream->codec;

  54.     switch(flv_codecid) {

  55.         //no distinction between S16 and S8 PCM codec flags

  56.         case FLV_CODECID_PCM:

  57.             acodec->codec_id = acodec->bits_per_coded_sample == 8 ? CODEC_ID_PCM_U8 :

  58. #if HAVE_BIGENDIAN

  59.                                 CODEC_ID_PCM_S16BE;

  60. #else

  61.                                 CODEC_ID_PCM_S16LE;

  62. #endif

  63.             break;

  64.         case FLV_CODECID_PCM_LE:

  65.             acodec->codec_id = acodec->bits_per_coded_sample == 8 ? CODEC_ID_PCM_U8 : CODEC_ID_PCM_S16LE; break;

  66.         case FLV_CODECID_AAC  : acodec->codec_id = CODEC_ID_AAC;                                    break;

  67.         case FLV_CODECID_ADPCM: acodec->codec_id = CODEC_ID_ADPCM_SWF;                              break;

  68.         case FLV_CODECID_SPEEX:

  69.             acodec->codec_id = CODEC_ID_SPEEX;

  70.             acodec->sample_rate = 16000;

  71.             break;

  72.         case FLV_CODECID_MP3  : acodec->codec_id = CODEC_ID_MP3      ; astream->need_parsing = AVSTREAM_PARSE_FULL; break;

  73.         case FLV_CODECID_NELLYMOSER_8KHZ_MONO:

  74.             acodec->sample_rate = 8000; //in case metadata does not otherwise declare samplerate

  75.             acodec->codec_id = CODEC_ID_NELLYMOSER;

  76.             break;

  77.         case FLV_CODECID_NELLYMOSER_16KHZ_MONO:

  78.             acodec->sample_rate = 16000;

  79.             acodec->codec_id = CODEC_ID_NELLYMOSER;

  80.             break;

  81.         case FLV_CODECID_NELLYMOSER:

  82.             acodec->codec_id = CODEC_ID_NELLYMOSER;

  83.             break;

  84.         default:

  85.             av_log(s, AV_LOG_INFO, "Unsupported audio codec (%x)\n", flv_codecid >> FLV_AUDIO_CODECID_OFFSET);

  86.             acodec->codec_tag = flv_codecid >> FLV_AUDIO_CODECID_OFFSET;

  87.     }

  88. }

  89. 

  90. static int flv_set_video_codec(AVFormatContext *s, AVStream *vstream, int flv_codecid) {

  91.     AVCodecContext *vcodec = vstream->codec;

  92.     switch(flv_codecid) {

  93.         case FLV_CODECID_H263  : vcodec->codec_id = CODEC_ID_FLV1   ; break;

  94.         case FLV_CODECID_REALH263: vcodec->codec_id = CODEC_ID_H263 ; break; // Really mean it this time

  95.         case FLV_CODECID_SCREEN: vcodec->codec_id = CODEC_ID_FLASHSV; break;

  96.         case FLV_CODECID_SCREEN2: vcodec->codec_id = CODEC_ID_FLASHSV2; break;

  97.         case FLV_CODECID_VP6   : vcodec->codec_id = CODEC_ID_VP6F   ;

  98.         case FLV_CODECID_VP6A  :

  99.             if(flv_codecid == FLV_CODECID_VP6A)

  100.                 vcodec->codec_id = CODEC_ID_VP6A;

  101.             if(vcodec->extradata_size != 1) {

  102.                 vcodec->extradata_size = 1;

  103.                 vcodec->extradata = av_malloc(1);

  104.             }

  105.             vcodec->extradata[0] = avio_r8(s->pb);

  106.             return 1; // 1 byte body size adjustment for flv_read_packet()

  107.         case FLV_CODECID_H264:

  108.             vcodec->codec_id = CODEC_ID_H264;

  109.             return 3; // not 4, reading packet type will consume one byte

  110.         case FLV_CODECID_MPEG4:

  111.             vcodec->codec_id = CODEC_ID_MPEG4;

  112.             return 3;

  113.         default:

  114.             av_log(s, AV_LOG_INFO, "Unsupported video codec (%x)\n", flv_codecid);

  115.             vcodec->codec_tag = flv_codecid;

  116.     }

  117. 

  118.     return 0;

  119. }

  120. 

  121. static int amf_get_string(AVIOContext *ioc, char *buffer, int buffsize) {

  122.     int length = avio_rb16(ioc);

  123.     if(length >= buffsize) {

  124.         avio_skip(ioc, length);

  125.         return -1;

  126.     }

  127. 

  128.     avio_read(ioc, buffer, length);

  129. 

  130.     buffer[length] = '\0';

  131. 

  132.     return length;

  133. }

  134. 

  135. static int parse_keyframes_index(AVFormatContext *s, AVIOContext *ioc, AVStream *vstream, int64_t max_pos) {

  136.     unsigned int timeslen = 0, fileposlen = 0, i;

  137.     char str_val[256];

  138.     int64_t *times = NULL;

  139.     int64_t *filepositions = NULL;

  140.     int ret = AVERROR(ENOSYS);

  141.     int64_t initial_pos = avio_tell(ioc);

  142. 

  143.     while (avio_tell(ioc) < max_pos - 2 && amf_get_string(ioc, str_val, sizeof(str_val)) > 0) {

  144.         int64_t** current_array;

  145.         unsigned int arraylen;

  146. 

  147.         // Expect array object in context

  148.         if (avio_r8(ioc) != AMF_DATA_TYPE_ARRAY)

  149.             break;

  150. 

  151.         arraylen = avio_rb32(ioc);

  152.         if(arraylen>>28)

  153.             break;

  154. 

  155.         if       (!strcmp(KEYFRAMES_TIMESTAMP_TAG , str_val) && !times){

  156.             current_array= &times;

  157.             timeslen= arraylen;

  158.         }else if (!strcmp(KEYFRAMES_BYTEOFFSET_TAG, str_val) && !filepositions){

  159.             current_array= &filepositions;

  160.             fileposlen= arraylen;

  161.         }else // unexpected metatag inside keyframes, will not use such metadata for indexing

  162.             break;

  163. 

  164.         if (!(*current_array = av_mallocz(sizeof(**current_array) * arraylen))) {

  165.             ret = AVERROR(ENOMEM);

  166.             goto finish;

  167.         }

  168. 

  169.         for (i = 0; i < arraylen && avio_tell(ioc) < max_pos - 1; i++) {

  170.             if (avio_r8(ioc) != AMF_DATA_TYPE_NUMBER)

  171.                 goto finish;

  172.             current_array[0][i] = av_int2dbl(avio_rb64(ioc));

  173.         }

  174.         if (times && filepositions) {

  175.             // All done, exiting at a position allowing amf_parse_object

  176.             // to finish parsing the object

  177.             ret = 0;

  178.             break;

  179.         }

  180.     }

  181. 

  182.     if (timeslen == fileposlen) {

  183.          for(i = 0; i < timeslen; i++)

  184.              av_add_index_entry(vstream, filepositions[i], times[i]*1000, 0, 0, AVINDEX_KEYFRAME);

  185.     } else

  186.         av_log(s, AV_LOG_WARNING, "Invalid keyframes object, skipping.\n");

  187. 

  188. finish:

  189.     av_freep(&times);

  190.     av_freep(&filepositions);

  191.     avio_seek(ioc, initial_pos, SEEK_SET);

  192.     return ret;

  193. }

  194. 

  195. static int amf_parse_object(AVFormatContext *s, AVStream *astream, AVStream *vstream, const char *key, int64_t max_pos, int depth) {

  196.     AVCodecContext *acodec, *vcodec;

  197.     AVIOContext *ioc;

  198.     AMFDataType amf_type;

  199.     char str_val[256];

  200.     double num_val;

  201. 

  202.     num_val = 0;

  203.     ioc = s->pb;

  204. 

  205.     amf_type = avio_r8(ioc);

  206. 

  207.     switch(amf_type) {

  208.         case AMF_DATA_TYPE_NUMBER:

  209.             num_val = av_int2dbl(avio_rb64(ioc)); break;

  210.         case AMF_DATA_TYPE_BOOL:

  211.             num_val = avio_r8(ioc); break;

  212.         case AMF_DATA_TYPE_STRING:

  213.             if(amf_get_string(ioc, str_val, sizeof(str_val)) < 0)

  214.                 return -1;

  215.             break;

  216.         case AMF_DATA_TYPE_OBJECT: {

  217.             unsigned int keylen;

  218. 

  219.             if (ioc->seekable && key && !strcmp(KEYFRAMES_TAG, key) && depth == 1)

  220.                 if (parse_keyframes_index(s, ioc, vstream, max_pos) < 0)

  221.                     av_log(s, AV_LOG_ERROR, "Keyframe index parsing failed\n");

  222. 

  223.             while(avio_tell(ioc) < max_pos - 2 && (keylen = avio_rb16(ioc))) {

  224.                 avio_skip(ioc, keylen); //skip key string

  225.                 if(amf_parse_object(s, NULL, NULL, NULL, max_pos, depth + 1) < 0)

  226.                     return -1; //if we couldn't skip, bomb out.

  227.             }

  228.             if(avio_r8(ioc) != AMF_END_OF_OBJECT)

  229.                 return -1;

  230.         }

  231.             break;

  232.         case AMF_DATA_TYPE_NULL:

  233.         case AMF_DATA_TYPE_UNDEFINED:

  234.         case AMF_DATA_TYPE_UNSUPPORTED:

  235.             break; //these take up no additional space

  236.         case AMF_DATA_TYPE_MIXEDARRAY:

  237.             avio_skip(ioc, 4); //skip 32-bit max array index

  238.             while(avio_tell(ioc) < max_pos - 2 && amf_get_string(ioc, str_val, sizeof(str_val)) > 0) {

  239.                 //this is the only case in which we would want a nested parse to not skip over the object

  240.                 if(amf_parse_object(s, astream, vstream, str_val, max_pos, depth + 1) < 0)

  241.                     return -1;

  242.             }

  243.             if(avio_r8(ioc) != AMF_END_OF_OBJECT)

  244.                 return -1;

  245.             break;

  246.         case AMF_DATA_TYPE_ARRAY: {

  247.             unsigned int arraylen, i;

  248. 

  249.             arraylen = avio_rb32(ioc);

  250.             for(i = 0; i < arraylen && avio_tell(ioc) < max_pos - 1; i++) {

  251.                 if(amf_parse_object(s, NULL, NULL, NULL, max_pos, depth + 1) < 0)

  252.                     return -1; //if we couldn't skip, bomb out.

  253.             }

  254.         }

  255.             break;

  256.         case AMF_DATA_TYPE_DATE:

  257.             avio_skip(ioc, 8 + 2); //timestamp (double) and UTC offset (int16)

  258.             break;

  259.         default: //unsupported type, we couldn't skip

  260.             return -1;

  261.     }

  262. 

  263.     if(depth == 1 && key) { //only look for metadata values when we are not nested and key != NULL

  264.         acodec = astream ? astream->codec : NULL;

  265.         vcodec = vstream ? vstream->codec : NULL;

  266. 

  267.         if(amf_type == AMF_DATA_TYPE_BOOL) {

  268.             av_strlcpy(str_val, num_val > 0 ? "true" : "false", sizeof(str_val));

  269.             av_dict_set(&s->metadata, key, str_val, 0);

  270.         } else if(amf_type == AMF_DATA_TYPE_NUMBER) {

  271.             snprintf(str_val, sizeof(str_val), "%.f", num_val);

  272.             av_dict_set(&s->metadata, key, str_val, 0);

  273.             if(!strcmp(key, "duration")) s->duration = num_val * AV_TIME_BASE;

  274.             else if(!strcmp(key, "videodatarate") && vcodec && 0 <= (int)(num_val * 1024.0))

  275.                 vcodec->bit_rate = num_val * 1024.0;

  276.             else if(!strcmp(key, "audiodatarate") && acodec && 0 <= (int)(num_val * 1024.0))

  277.                 acodec->bit_rate = num_val * 1024.0;

  278.         } else if(amf_type == AMF_DATA_TYPE_OBJECT){

  279.             if(s->nb_streams==1 && ((!acodec && !strcmp(key, "audiocodecid")) || (!vcodec && !strcmp(key, "videocodecid")))){

  280.                 s->ctx_flags &= ~AVFMTCTX_NOHEADER; //If there is either audio/video missing, codecid will be an empty object

  281.             }

  282.         } else if (amf_type == AMF_DATA_TYPE_STRING)

  283.             av_dict_set(&s->metadata, key, str_val, 0);

  284.     }

  285. 

  286.     return 0;

  287. }

  288. 

  289. static int flv_read_metabody(AVFormatContext *s, int64_t next_pos) {

  290.     AMFDataType type;

  291.     AVStream *stream, *astream, *vstream, *dstream;

  292.     AVIOContext *ioc;

  293.     int i;

  294.     char buffer[11]; //only needs to hold the string "onMetaData". Anything longer is something we don't want.

  295. 

  296.     vstream = astream = dstream = NULL;

  297.     ioc = s->pb;

  298. 

  299.     //first object needs to be "onMetaData" string

  300.     type = avio_r8(ioc);

  301.     if(type != AMF_DATA_TYPE_STRING || amf_get_string(ioc, buffer, sizeof(buffer)) < 0 || strcmp(buffer, "onMetaData"))

  302.         return -1;

  303. 

  304.     //find the streams now so that amf_parse_object doesn't need to do the lookup every time it is called.

  305.     for(i = 0; i < s->nb_streams; i++) {

  306.         stream = s->streams[i];

  307.         if(stream->codec->codec_type == AVMEDIA_TYPE_VIDEO) vstream = stream;

  308.         else if(stream->codec->codec_type == AVMEDIA_TYPE_AUDIO) astream = stream;

  309.         else if(stream->codec->codec_type == AVMEDIA_TYPE_VIDEO) dstream = stream;

  310.     }

  311. 

  312.     //parse the second object (we want a mixed array)

  313.     if(amf_parse_object(s, astream, vstream, buffer, next_pos, 0) < 0)

  314.         return -1;

  315. 

  316.     return 0;

  317. }

  318. 

  319. static AVStream *create_stream(AVFormatContext *s, int stream_type){

  320.     AVStream *st = av_new_stream(s, stream_type);

  321.     if (!st)

  322.         return NULL;

  323.     switch(stream_type) {

  324.         case FLV_STREAM_TYPE_VIDEO:    st->codec->codec_type = AVMEDIA_TYPE_VIDEO;    break;

  325.         case FLV_STREAM_TYPE_AUDIO:    st->codec->codec_type = AVMEDIA_TYPE_AUDIO;    break;

  326.         case FLV_STREAM_TYPE_DATA:

  327.             st->codec->codec_type = AVMEDIA_TYPE_DATA;

  328.             st->codec->codec_id = CODEC_ID_NONE; // Going to rely on copy for now

  329.             av_log(s, AV_LOG_DEBUG, "Data stream created\n");

  330.     }

  331.     av_set_pts_info(st, 32, 1, 1000); /* 32 bit pts in ms */

  332.     return st;

  333. }

  334. 

  335. static int flv_read_header(AVFormatContext *s,

  336.                            AVFormatParameters *ap)

  337. {

  338.     int offset, flags;

  339. 

  340.     avio_skip(s->pb, 4);

  341.     flags = avio_r8(s->pb);

  342.     /* old flvtool cleared this field */

  343.     /* FIXME: better fix needed */

  344.     if (!flags) {

  345.         flags = FLV_HEADER_FLAG_HASVIDEO | FLV_HEADER_FLAG_HASAUDIO;

  346.         av_log(s, AV_LOG_WARNING, "Broken FLV file, which says no streams present, this might fail\n");

  347.     }

  348. 

  349.     if((flags & (FLV_HEADER_FLAG_HASVIDEO|FLV_HEADER_FLAG_HASAUDIO))

  350.              != (FLV_HEADER_FLAG_HASVIDEO|FLV_HEADER_FLAG_HASAUDIO))

  351.         s->ctx_flags |= AVFMTCTX_NOHEADER;

  352. 

  353.     if(flags & FLV_HEADER_FLAG_HASVIDEO){

  354.         if(!create_stream(s, FLV_STREAM_TYPE_VIDEO))

  355.             return AVERROR(ENOMEM);

  356.     }

  357.     if(flags & FLV_HEADER_FLAG_HASAUDIO){

  358.         if(!create_stream(s, FLV_STREAM_TYPE_AUDIO))

  359.             return AVERROR(ENOMEM);

  360.     }

  361.     // Flag doesn't indicate whether or not there is script-data present. Must

  362.     // create that stream if it's encountered.

  363. 

  364.     offset = avio_rb32(s->pb);

  365.     avio_seek(s->pb, offset, SEEK_SET);

  366.     avio_skip(s->pb, 4);

  367. 

  368.     s->start_time = 0;

  369. 

  370.     return 0;

  371. }

  372. 

  373. static int flv_get_extradata(AVFormatContext *s, AVStream *st, int size)

  374. {

  375.     av_free(st->codec->extradata);

  376.     st->codec->extradata = av_mallocz(size + FF_INPUT_BUFFER_PADDING_SIZE);

  377.     if (!st->codec->extradata)

  378.         return AVERROR(ENOMEM);

  379.     st->codec->extradata_size = size;

  380.     avio_read(s->pb, st->codec->extradata, st->codec->extradata_size);

  381.     return 0;

  382. }

  383. 

  384. static int flv_read_packet(AVFormatContext *s, AVPacket *pkt)

  385. {

  386.     FLVContext *flv = s->priv_data;

  387.     int ret, i, type, size, flags;

  388.     int stream_type=-1;

  389.     int64_t next, pos;

  390.     int64_t dts, pts = AV_NOPTS_VALUE;

  391.     AVStream *st = NULL;

  392. 

  393.  for(;;avio_skip(s->pb, 4)){ /* pkt size is repeated at end. skip it */

  394.     pos = avio_tell(s->pb);

  395.     type = avio_r8(s->pb);

  396.     size = avio_rb24(s->pb);

  397.     dts = avio_rb24(s->pb);

  398.     dts |= avio_r8(s->pb) << 24;

  399.     av_dlog(s, "type:%d, size:%d, dts:%"PRId64"\n", type, size, dts);

  400.     if (url_feof(s->pb))

  401.         return AVERROR_EOF;

  402.     avio_skip(s->pb, 3); /* stream id, always 0 */

  403.     flags = 0;

  404. 

  405.     if(size == 0)

  406.         continue;

  407. 

  408.     next= size + avio_tell(s->pb);

  409. 

  410.     if (type == FLV_TAG_TYPE_AUDIO) {

  411.         stream_type=FLV_STREAM_TYPE_AUDIO;

  412.         flags = avio_r8(s->pb);

  413.         size--;

  414.     } else if (type == FLV_TAG_TYPE_VIDEO) {

  415.         stream_type=FLV_STREAM_TYPE_VIDEO;

  416.         flags = avio_r8(s->pb);

  417.         size--;

  418.         if ((flags & 0xf0) == 0x50) /* video info / command frame */

  419.             goto skip;

  420.     } else if (type == FLV_TAG_TYPE_META) {

  421.         if (size > 13+1+4 && dts == 0) { // Header-type metadata stuff

  422.             flv_read_metabody(s, next);

  423.             goto skip;

  424.         } else if (dts != 0) { // Script-data "special" metadata frames - don't skip

  425.             stream_type=FLV_STREAM_TYPE_DATA;

  426.         } else {

  427.             goto skip;

  428.         }

  429.     } else {

  430.         av_log(s, AV_LOG_DEBUG, "skipping flv packet: type %d, size %d, flags %d\n", type, size, flags);

  431.     skip:

  432.         avio_seek(s->pb, next, SEEK_SET);

  433.         continue;

  434.     }

  435. 

  436.     /* skip empty data packets */

  437.     if (!size)

  438.         continue;

  439. 

  440.     /* now find stream */

  441.     for(i=0;i<s->nb_streams;i++) {

  442.         st = s->streams[i];

  443.         if (st->id == stream_type)

  444.             break;

  445.     }

  446.     if(i == s->nb_streams){

  447.         av_log(s, AV_LOG_WARNING, "Stream discovered after head already parsed\n");

  448.         st= create_stream(s, stream_type);

  449.         s->ctx_flags &= ~AVFMTCTX_NOHEADER;

  450.     }

  451.     av_dlog(s, "%d %X %d \n", stream_type, flags, st->discard);

  452.     if(  (st->discard >= AVDISCARD_NONKEY && !((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY || (stream_type == FLV_STREAM_TYPE_AUDIO)))

  453.        ||(st->discard >= AVDISCARD_BIDIR  &&  ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_DISP_INTER && (stream_type == FLV_STREAM_TYPE_VIDEO)))

  454.        || st->discard >= AVDISCARD_ALL

  455.        ){

  456.         avio_seek(s->pb, next, SEEK_SET);

  457.         continue;

  458.     }

  459.     if ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY)

  460.         av_add_index_entry(st, pos, dts, size, 0, AVINDEX_KEYFRAME);

  461.     break;

  462.  }

  463. 

  464.     // if not streamed and no duration from metadata then seek to end to find the duration from the timestamps

  465.     if(s->pb->seekable && (!s->duration || s->duration==AV_NOPTS_VALUE)){

  466.         int size;

  467.         const int64_t pos= avio_tell(s->pb);

  468.         const int64_t fsize= avio_size(s->pb);

  469.         avio_seek(s->pb, fsize-4, SEEK_SET);

  470.         size= avio_rb32(s->pb);

  471.         avio_seek(s->pb, fsize-3-size, SEEK_SET);

  472.         if(size == avio_rb24(s->pb) + 11){

  473.             uint32_t ts = avio_rb24(s->pb);

  474.             ts |= avio_r8(s->pb) << 24;

  475.             s->duration = ts * (int64_t)AV_TIME_BASE / 1000;

  476.         }

  477.         avio_seek(s->pb, pos, SEEK_SET);

  478.     }

  479. 

  480.     if(stream_type == FLV_STREAM_TYPE_AUDIO){

  481.         if(!st->codec->channels || !st->codec->sample_rate || !st->codec->bits_per_coded_sample) {

  482.             st->codec->channels = (flags & FLV_AUDIO_CHANNEL_MASK) == FLV_STEREO ? 2 : 1;

  483.             st->codec->sample_rate = (44100 << ((flags & FLV_AUDIO_SAMPLERATE_MASK) >> FLV_AUDIO_SAMPLERATE_OFFSET) >> 3);

  484.             st->codec->bits_per_coded_sample = (flags & FLV_AUDIO_SAMPLESIZE_MASK) ? 16 : 8;

  485.         }

  486.         if(!st->codec->codec_id){

  487.             flv_set_audio_codec(s, st, flags & FLV_AUDIO_CODECID_MASK);

  488.         }

  489.     } else if(stream_type == FLV_STREAM_TYPE_VIDEO) {

  490.         size -= flv_set_video_codec(s, st, flags & FLV_VIDEO_CODECID_MASK);

  491.     }

  492. 

  493.     if (st->codec->codec_id == CODEC_ID_AAC ||

  494.         st->codec->codec_id == CODEC_ID_H264 ||

  495.         st->codec->codec_id == CODEC_ID_MPEG4) {

  496.         int type = avio_r8(s->pb);

  497.         size--;

  498.         if (st->codec->codec_id == CODEC_ID_H264 || st->codec->codec_id == CODEC_ID_MPEG4) {

  499.             int32_t cts = (avio_rb24(s->pb)+0xff800000)^0xff800000; // sign extension

  500.             pts = dts + cts;

  501.             if (cts < 0) { // dts are wrong

  502.                 flv->wrong_dts = 1;

  503.                 av_log(s, AV_LOG_WARNING, "negative cts, previous timestamps might be wrong\n");

  504.             }

  505.             if (flv->wrong_dts)

  506.                 dts = AV_NOPTS_VALUE;

  507.         }

  508.         if (type == 0) {

  509.             if ((ret = flv_get_extradata(s, st, size)) < 0)

  510.                 return ret;

  511.             if (st->codec->codec_id == CODEC_ID_AAC) {

  512.                 MPEG4AudioConfig cfg;

  513.                 ff_mpeg4audio_get_config(&cfg, st->codec->extradata,

  514.                                          st->codec->extradata_size);

  515.                 st->codec->channels = cfg.channels;

  516.                 if (cfg.ext_sample_rate)

  517.                     st->codec->sample_rate = cfg.ext_sample_rate;

  518.                 else

  519.                     st->codec->sample_rate = cfg.sample_rate;

  520.                 av_dlog(s, "mp4a config channels %d sample rate %d\n",

  521.                         st->codec->channels, st->codec->sample_rate);

  522.             }

  523. 

  524.             ret = AVERROR(EAGAIN);

  525.             goto leave;

  526.         }

  527.     }

  528. 

  529.     /* skip empty data packets */

  530.     if (!size) {

  531.         ret = AVERROR(EAGAIN);

  532.         goto leave;

  533.     }

  534. 

  535.     ret= av_get_packet(s->pb, pkt, size);

  536.     if (ret < 0) {

  537.         return AVERROR(EIO);

  538.     }

  539.     /* note: we need to modify the packet size here to handle the last

  540.        packet */

  541.     pkt->size = ret;

  542.     pkt->dts = dts;

  543.     pkt->pts = pts == AV_NOPTS_VALUE ? dts : pts;

  544.     pkt->stream_index = st->index;

  545. 

  546.     if (    stream_type == FLV_STREAM_TYPE_AUDIO ||

  547.             ((flags & FLV_VIDEO_FRAMETYPE_MASK) == FLV_FRAME_KEY) ||

  548.             stream_type == FLV_STREAM_TYPE_DATA)

  549.         pkt->flags |= AV_PKT_FLAG_KEY;

  550. 

  551. leave:

  552.     avio_skip(s->pb, 4);

  553.     return ret;

  554. }

  555. 

  556. static int flv_read_seek(AVFormatContext *s, int stream_index,

  557.     int64_t ts, int flags)

  558. {

  559.     return avio_seek_time(s->pb, stream_index, ts, flags);

  560. }

  561. 

  562. #if 0 /* don't know enough to implement this */

  563. static int flv_read_seek2(AVFormatContext *s, int stream_index,

  564.     int64_t min_ts, int64_t ts, int64_t max_ts, int flags)

  565. {

  566.     int ret = AVERROR(ENOSYS);

  567. 

  568.     if (ts - min_ts > (uint64_t)(max_ts - ts)) flags |= AVSEEK_FLAG_BACKWARD;

  569. 

  570.     if (!s->pb->seekable) {

  571.         if (stream_index < 0) {

  572.             stream_index = av_find_default_stream_index(s);

  573.             if (stream_index < 0)

  574.                 return -1;

  575. 

  576.             /* timestamp for default must be expressed in AV_TIME_BASE units */

  577.             ts = av_rescale_rnd(ts, 1000, AV_TIME_BASE,

  578.                 flags & AVSEEK_FLAG_BACKWARD ? AV_ROUND_DOWN : AV_ROUND_UP);

  579.         }

  580.         ret = avio_seek_time(s->pb, stream_index, ts, flags);

  581.     }

  582. 

  583.     if (ret == AVERROR(ENOSYS))

  584.         ret = av_seek_frame(s, stream_index, ts, flags);

  585.     return ret;

  586. }

  587. #endif

  588. 

  589. AVInputFormat ff_flv_demuxer = {

  590.     .name           = "flv",

  591.     .long_name      = NULL_IF_CONFIG_SMALL("FLV format"),

  592.     .priv_data_size = sizeof(FLVContext),

  593.     .read_probe     = flv_probe,

  594.     .read_header    = flv_read_header,

  595.     .read_packet    = flv_read_packet,

  596.     .read_seek = flv_read_seek,

  597. #if 0

  598.     .read_seek2 = flv_read_seek2,

  599. #endif

  600.     .extensions = "flv",

  601.     .value = CODEC_ID_FLV1,

  602. };