ffmpeg/libavformat/riff.c
Michael Niedermayer 7b24f9b425 libnut uses "MP3 " for mp3
Originally committed as revision 6963 to svn://svn.ffmpeg.org/ffmpeg/trunk
2006-11-11 00:29:49 +00:00

469 lines
17 KiB
C

/*
* RIFF codec tags
* Copyright (c) 2000 Fabrice Bellard.
*
* 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 "avformat.h"
#include "avcodec.h"
#include "riff.h"
/* Note: when encoding, the first matching tag is used, so order is
important if multiple tags possible for a given codec. */
const CodecTag codec_bmp_tags[] = {
{ CODEC_ID_H264, MKTAG('H', '2', '6', '4') },
{ CODEC_ID_H264, MKTAG('h', '2', '6', '4') },
{ CODEC_ID_H264, MKTAG('X', '2', '6', '4') },
{ CODEC_ID_H264, MKTAG('x', '2', '6', '4') },
{ CODEC_ID_H264, MKTAG('a', 'v', 'c', '1') },
{ CODEC_ID_H264, MKTAG('V', 'S', 'S', 'H') },
{ CODEC_ID_H263, MKTAG('H', '2', '6', '3') },
{ CODEC_ID_H263P, MKTAG('H', '2', '6', '3') },
{ CODEC_ID_H263I, MKTAG('I', '2', '6', '3') }, /* intel h263 */
{ CODEC_ID_H261, MKTAG('H', '2', '6', '1') },
/* added based on MPlayer */
{ CODEC_ID_H263P, MKTAG('U', '2', '6', '3') },
{ CODEC_ID_H263P, MKTAG('v', 'i', 'v', '1') },
{ CODEC_ID_MPEG4, MKTAG('F', 'M', 'P', '4')},
{ CODEC_ID_MPEG4, MKTAG('D', 'I', 'V', 'X'), .invalid_asf = 1 },
{ CODEC_ID_MPEG4, MKTAG('D', 'X', '5', '0'), .invalid_asf = 1 },
{ CODEC_ID_MPEG4, MKTAG('X', 'V', 'I', 'D'), .invalid_asf = 1 },
{ CODEC_ID_MPEG4, MKTAG('M', 'P', '4', 'S') },
{ CODEC_ID_MPEG4, MKTAG('M', '4', 'S', '2') },
{ CODEC_ID_MPEG4, MKTAG(0x04, 0, 0, 0) }, /* some broken avi use this */
/* added based on MPlayer */
{ CODEC_ID_MPEG4, MKTAG('D', 'I', 'V', '1') },
{ CODEC_ID_MPEG4, MKTAG('B', 'L', 'Z', '0') },
{ CODEC_ID_MPEG4, MKTAG('m', 'p', '4', 'v') },
{ CODEC_ID_MPEG4, MKTAG('U', 'M', 'P', '4') },
{ CODEC_ID_MPEG4, MKTAG('W', 'V', '1', 'F') },
{ CODEC_ID_MPEG4, MKTAG('S', 'E', 'D', 'G') },
{ CODEC_ID_MPEG4, MKTAG('R', 'M', 'P', '4') },
{ CODEC_ID_MSMPEG4V3, MKTAG('D', 'I', 'V', '3'), .invalid_asf = 1 }, /* default signature when using MSMPEG4 */
{ CODEC_ID_MSMPEG4V3, MKTAG('M', 'P', '4', '3') },
/* added based on MPlayer */
{ CODEC_ID_MSMPEG4V3, MKTAG('M', 'P', 'G', '3') },
{ CODEC_ID_MSMPEG4V3, MKTAG('D', 'I', 'V', '5') },
{ CODEC_ID_MSMPEG4V3, MKTAG('D', 'I', 'V', '6') },
{ CODEC_ID_MSMPEG4V3, MKTAG('D', 'I', 'V', '4') },
{ CODEC_ID_MSMPEG4V3, MKTAG('A', 'P', '4', '1') },
{ CODEC_ID_MSMPEG4V3, MKTAG('C', 'O', 'L', '1') },
{ CODEC_ID_MSMPEG4V3, MKTAG('C', 'O', 'L', '0') },
{ CODEC_ID_MSMPEG4V2, MKTAG('M', 'P', '4', '2') },
/* added based on MPlayer */
{ CODEC_ID_MSMPEG4V2, MKTAG('D', 'I', 'V', '2') },
{ CODEC_ID_MSMPEG4V1, MKTAG('M', 'P', 'G', '4') },
{ CODEC_ID_WMV1, MKTAG('W', 'M', 'V', '1') },
/* added based on MPlayer */
{ CODEC_ID_WMV2, MKTAG('W', 'M', 'V', '2') },
{ CODEC_ID_DVVIDEO, MKTAG('d', 'v', 's', 'd') },
{ CODEC_ID_DVVIDEO, MKTAG('d', 'v', 'h', 'd') },
{ CODEC_ID_DVVIDEO, MKTAG('d', 'v', 's', 'l') },
{ CODEC_ID_DVVIDEO, MKTAG('d', 'v', '2', '5') },
{ CODEC_ID_MPEG1VIDEO, MKTAG('m', 'p', 'g', '1') },
{ CODEC_ID_MPEG1VIDEO, MKTAG('m', 'p', 'g', '2') },
{ CODEC_ID_MPEG2VIDEO, MKTAG('m', 'p', 'g', '2') },
{ CODEC_ID_MPEG2VIDEO, MKTAG('M', 'P', 'E', 'G') },
{ CODEC_ID_MPEG1VIDEO, MKTAG('P', 'I', 'M', '1') },
{ CODEC_ID_MPEG1VIDEO, MKTAG('V', 'C', 'R', '2') },
{ CODEC_ID_MPEG1VIDEO, 0x10000001 },
{ CODEC_ID_MPEG2VIDEO, 0x10000002 },
{ CODEC_ID_MPEG2VIDEO, MKTAG('D', 'V', 'R', ' ') },
{ CODEC_ID_MJPEG, MKTAG('M', 'J', 'P', 'G') },
{ CODEC_ID_MJPEG, MKTAG('L', 'J', 'P', 'G') },
{ CODEC_ID_LJPEG, MKTAG('L', 'J', 'P', 'G') },
{ CODEC_ID_MJPEG, MKTAG('J', 'P', 'G', 'L') }, /* Pegasus lossless JPEG */
{ CODEC_ID_MJPEG, MKTAG('M', 'J', 'L', 'S') }, /* JPEG-LS custom FOURCC for avi - decoder */
{ CODEC_ID_JPEGLS, MKTAG('M', 'J', 'L', 'S') }, /* JPEG-LS custom FOURCC for avi - encoder */
{ CODEC_ID_HUFFYUV, MKTAG('H', 'F', 'Y', 'U') },
{ CODEC_ID_FFVHUFF, MKTAG('F', 'F', 'V', 'H') },
{ CODEC_ID_CYUV, MKTAG('C', 'Y', 'U', 'V') },
{ CODEC_ID_RAWVIDEO, 0 },
{ CODEC_ID_RAWVIDEO, MKTAG('I', '4', '2', '0') },
{ CODEC_ID_RAWVIDEO, MKTAG('Y', 'U', 'Y', '2') },
{ CODEC_ID_RAWVIDEO, MKTAG('Y', '4', '2', '2') },
{ CODEC_ID_RAWVIDEO, MKTAG('Y', 'V', '1', '2') },
{ CODEC_ID_RAWVIDEO, MKTAG('U', 'Y', 'V', 'Y') },
{ CODEC_ID_RAWVIDEO, MKTAG('I', 'Y', 'U', 'V') },
{ CODEC_ID_RAWVIDEO, MKTAG('Y', '8', '0', '0') },
{ CODEC_ID_INDEO3, MKTAG('I', 'V', '3', '1') },
{ CODEC_ID_INDEO3, MKTAG('I', 'V', '3', '2') },
{ CODEC_ID_VP3, MKTAG('V', 'P', '3', '1') },
{ CODEC_ID_VP3, MKTAG('V', 'P', '3', '0') },
{ CODEC_ID_VP5, MKTAG('V', 'P', '5', '0') },
{ CODEC_ID_VP6, MKTAG('V', 'P', '6', '2') },
{ CODEC_ID_ASV1, MKTAG('A', 'S', 'V', '1') },
{ CODEC_ID_ASV2, MKTAG('A', 'S', 'V', '2') },
{ CODEC_ID_VCR1, MKTAG('V', 'C', 'R', '1') },
{ CODEC_ID_FFV1, MKTAG('F', 'F', 'V', '1') },
{ CODEC_ID_XAN_WC4, MKTAG('X', 'x', 'a', 'n') },
{ CODEC_ID_MSRLE, MKTAG('m', 'r', 'l', 'e') },
{ CODEC_ID_MSRLE, MKTAG(0x1, 0x0, 0x0, 0x0) },
{ CODEC_ID_MSVIDEO1, MKTAG('M', 'S', 'V', 'C') },
{ CODEC_ID_MSVIDEO1, MKTAG('m', 's', 'v', 'c') },
{ CODEC_ID_MSVIDEO1, MKTAG('C', 'R', 'A', 'M') },
{ CODEC_ID_MSVIDEO1, MKTAG('c', 'r', 'a', 'm') },
{ CODEC_ID_MSVIDEO1, MKTAG('W', 'H', 'A', 'M') },
{ CODEC_ID_MSVIDEO1, MKTAG('w', 'h', 'a', 'm') },
{ CODEC_ID_CINEPAK, MKTAG('c', 'v', 'i', 'd') },
{ CODEC_ID_TRUEMOTION1, MKTAG('D', 'U', 'C', 'K') },
{ CODEC_ID_MSZH, MKTAG('M', 'S', 'Z', 'H') },
{ CODEC_ID_ZLIB, MKTAG('Z', 'L', 'I', 'B') },
{ CODEC_ID_SNOW, MKTAG('S', 'N', 'O', 'W') },
{ CODEC_ID_4XM, MKTAG('4', 'X', 'M', 'V') },
{ CODEC_ID_FLV1, MKTAG('F', 'L', 'V', '1') },
{ CODEC_ID_FLASHSV, MKTAG('F', 'S', 'V', '1') },
{ CODEC_ID_VP6F, MKTAG('V', 'P', '6', 'F') },
{ CODEC_ID_SVQ1, MKTAG('s', 'v', 'q', '1') },
{ CODEC_ID_TSCC, MKTAG('t', 's', 'c', 'c') },
{ CODEC_ID_ULTI, MKTAG('U', 'L', 'T', 'I') },
{ CODEC_ID_VIXL, MKTAG('V', 'I', 'X', 'L') },
{ CODEC_ID_QPEG, MKTAG('Q', 'P', 'E', 'G') },
{ CODEC_ID_QPEG, MKTAG('Q', '1', '.', '0') },
{ CODEC_ID_QPEG, MKTAG('Q', '1', '.', '1') },
{ CODEC_ID_WMV3, MKTAG('W', 'M', 'V', '3') },
{ CODEC_ID_VC1, MKTAG('W', 'V', 'C', '1') },
{ CODEC_ID_LOCO, MKTAG('L', 'O', 'C', 'O') },
{ CODEC_ID_WNV1, MKTAG('W', 'N', 'V', '1') },
{ CODEC_ID_AASC, MKTAG('A', 'A', 'S', 'C') },
{ CODEC_ID_INDEO2, MKTAG('R', 'T', '2', '1') },
{ CODEC_ID_FRAPS, MKTAG('F', 'P', 'S', '1') },
{ CODEC_ID_THEORA, MKTAG('t', 'h', 'e', 'o') },
{ CODEC_ID_TRUEMOTION2, MKTAG('T', 'M', '2', '0') },
{ CODEC_ID_CSCD, MKTAG('C', 'S', 'C', 'D') },
{ CODEC_ID_ZMBV, MKTAG('Z', 'M', 'B', 'V') },
{ CODEC_ID_KMVC, MKTAG('K', 'M', 'V', 'C') },
{ CODEC_ID_CAVS, MKTAG('C', 'A', 'V', 'S') },
{ CODEC_ID_JPEG2000, MKTAG('M', 'J', '2', 'C') },
{ CODEC_ID_VMNC, MKTAG('V', 'M', 'n', 'c') },
{ CODEC_ID_NONE, 0 },
};
const CodecTag codec_wav_tags[] = {
{ CODEC_ID_MP2, 0x50 },
{ CODEC_ID_MP3, 0x55 },
{ CODEC_ID_AC3, 0x2000 },
{ CODEC_ID_DTS, 0x2001 },
{ CODEC_ID_PCM_S16LE, 0x01 },
{ CODEC_ID_PCM_U8, 0x01 }, /* must come after s16le in this list */
{ CODEC_ID_PCM_S24LE, 0x01 },
{ CODEC_ID_PCM_S32LE, 0x01 },
{ CODEC_ID_PCM_ALAW, 0x06 },
{ CODEC_ID_PCM_MULAW, 0x07 },
{ CODEC_ID_ADPCM_MS, 0x02 },
{ CODEC_ID_ADPCM_IMA_WAV, 0x11 },
{ CODEC_ID_ADPCM_YAMAHA, 0x20 },
{ CODEC_ID_ADPCM_G726, 0x45 },
{ CODEC_ID_ADPCM_IMA_DK4, 0x61 }, /* rogue format number */
{ CODEC_ID_ADPCM_IMA_DK3, 0x62 }, /* rogue format number */
{ CODEC_ID_WMAV1, 0x160 },
{ CODEC_ID_WMAV2, 0x161 },
{ CODEC_ID_AAC, 0x706d },
{ CODEC_ID_AAC, 0xff },
{ CODEC_ID_VORBIS, ('V'<<8)+'o' }, //HACK/FIXME, does vorbis in WAV/AVI have an (in)official id?
{ CODEC_ID_SONIC, 0x2048 },
{ CODEC_ID_SONIC_LS, 0x2048 },
{ CODEC_ID_ADPCM_CT, 0x200 },
{ CODEC_ID_ADPCM_SWF, ('S'<<8)+'F' },
{ CODEC_ID_TRUESPEECH, 0x22 },
{ CODEC_ID_FLAC, 0xF1AC },
{ CODEC_ID_IMC, 0x401 },
/* FIXME: All of the IDs below are not 16 bit and thus illegal. */
// for NuppelVideo (nuv.c)
{ CODEC_ID_PCM_S16LE, MKTAG('R', 'A', 'W', 'A') },
{ CODEC_ID_MP3, MKTAG('L', 'A', 'M', 'E') },
{ CODEC_ID_MP3, MKTAG('M', 'P', '3', ' ') },
{ 0, 0 },
};
unsigned int codec_get_tag(const CodecTag *tags, int id)
{
while (tags->id != CODEC_ID_NONE) {
if (tags->id == id)
return tags->tag;
tags++;
}
return 0;
}
unsigned int codec_get_asf_tag(const CodecTag *tags, unsigned int id)
{
while (tags->id != CODEC_ID_NONE) {
if (!tags->invalid_asf && tags->id == id)
return tags->tag;
tags++;
}
return 0;
}
enum CodecID codec_get_id(const CodecTag *tags, unsigned int tag)
{
while (tags->id != CODEC_ID_NONE) {
if( toupper((tag >> 0)&0xFF) == toupper((tags->tag >> 0)&0xFF)
&& toupper((tag >> 8)&0xFF) == toupper((tags->tag >> 8)&0xFF)
&& toupper((tag >>16)&0xFF) == toupper((tags->tag >>16)&0xFF)
&& toupper((tag >>24)&0xFF) == toupper((tags->tag >>24)&0xFF))
return tags->id;
tags++;
}
return CODEC_ID_NONE;
}
unsigned int codec_get_bmp_tag(int id)
{
return codec_get_tag(codec_bmp_tags, id);
}
unsigned int codec_get_wav_tag(int id)
{
return codec_get_tag(codec_wav_tags, id);
}
enum CodecID codec_get_bmp_id(unsigned int tag)
{
return codec_get_id(codec_bmp_tags, tag);
}
enum CodecID codec_get_wav_id(unsigned int tag)
{
return codec_get_id(codec_wav_tags, tag);
}
#ifdef CONFIG_MUXERS
offset_t start_tag(ByteIOContext *pb, const char *tag)
{
put_tag(pb, tag);
put_le32(pb, 0);
return url_ftell(pb);
}
void end_tag(ByteIOContext *pb, offset_t start)
{
offset_t pos;
pos = url_ftell(pb);
url_fseek(pb, start - 4, SEEK_SET);
put_le32(pb, (uint32_t)(pos - start));
url_fseek(pb, pos, SEEK_SET);
}
/* WAVEFORMATEX header */
/* returns the size or -1 on error */
int put_wav_header(ByteIOContext *pb, AVCodecContext *enc)
{
int bps, blkalign, bytespersec;
int hdrsize = 18;
if(!enc->codec_tag || enc->codec_tag > 0xffff)
enc->codec_tag = codec_get_tag(codec_wav_tags, enc->codec_id);
if(!enc->codec_tag || enc->codec_tag > 0xffff)
return -1;
put_le16(pb, enc->codec_tag);
put_le16(pb, enc->channels);
put_le32(pb, enc->sample_rate);
if (enc->codec_id == CODEC_ID_PCM_U8 ||
enc->codec_id == CODEC_ID_PCM_ALAW ||
enc->codec_id == CODEC_ID_PCM_MULAW) {
bps = 8;
} else if (enc->codec_id == CODEC_ID_MP2 || enc->codec_id == CODEC_ID_MP3) {
bps = 0;
} else if (enc->codec_id == CODEC_ID_ADPCM_IMA_WAV || enc->codec_id == CODEC_ID_ADPCM_MS || enc->codec_id == CODEC_ID_ADPCM_G726 || enc->codec_id == CODEC_ID_ADPCM_YAMAHA) { //
bps = 4;
} else if (enc->codec_id == CODEC_ID_PCM_S24LE) {
bps = 24;
} else if (enc->codec_id == CODEC_ID_PCM_S32LE) {
bps = 32;
} else {
bps = 16;
}
if (enc->codec_id == CODEC_ID_MP2 || enc->codec_id == CODEC_ID_MP3) {
blkalign = enc->frame_size; //this is wrong, but seems many demuxers dont work if this is set correctly
//blkalign = 144 * enc->bit_rate/enc->sample_rate;
} else if (enc->codec_id == CODEC_ID_ADPCM_G726) { //
blkalign = 1;
} else if (enc->block_align != 0) { /* specified by the codec */
blkalign = enc->block_align;
} else
blkalign = enc->channels*bps >> 3;
if (enc->codec_id == CODEC_ID_PCM_U8 ||
enc->codec_id == CODEC_ID_PCM_S24LE ||
enc->codec_id == CODEC_ID_PCM_S32LE ||
enc->codec_id == CODEC_ID_PCM_S16LE) {
bytespersec = enc->sample_rate * blkalign;
} else {
bytespersec = enc->bit_rate / 8;
}
put_le32(pb, bytespersec); /* bytes per second */
put_le16(pb, blkalign); /* block align */
put_le16(pb, bps); /* bits per sample */
if (enc->codec_id == CODEC_ID_MP3) {
put_le16(pb, 12); /* wav_extra_size */
hdrsize += 12;
put_le16(pb, 1); /* wID */
put_le32(pb, 2); /* fdwFlags */
put_le16(pb, 1152); /* nBlockSize */
put_le16(pb, 1); /* nFramesPerBlock */
put_le16(pb, 1393); /* nCodecDelay */
} else if (enc->codec_id == CODEC_ID_MP2) {
put_le16(pb, 22); /* wav_extra_size */
hdrsize += 22;
put_le16(pb, 2); /* fwHeadLayer */
put_le32(pb, enc->bit_rate); /* dwHeadBitrate */
put_le16(pb, enc->channels == 2 ? 1 : 8); /* fwHeadMode */
put_le16(pb, 0); /* fwHeadModeExt */
put_le16(pb, 1); /* wHeadEmphasis */
put_le16(pb, 16); /* fwHeadFlags */
put_le32(pb, 0); /* dwPTSLow */
put_le32(pb, 0); /* dwPTSHigh */
} else if (enc->codec_id == CODEC_ID_ADPCM_IMA_WAV) {
put_le16(pb, 2); /* wav_extra_size */
hdrsize += 2;
put_le16(pb, ((enc->block_align - 4 * enc->channels) / (4 * enc->channels)) * 8 + 1); /* wSamplesPerBlock */
} else if(enc->extradata_size){
put_le16(pb, enc->extradata_size);
put_buffer(pb, enc->extradata, enc->extradata_size);
hdrsize += enc->extradata_size;
if(hdrsize&1){
hdrsize++;
put_byte(pb, 0);
}
} else {
hdrsize -= 2;
}
return hdrsize;
}
/* BITMAPINFOHEADER header */
void put_bmp_header(ByteIOContext *pb, AVCodecContext *enc, const CodecTag *tags, int for_asf)
{
put_le32(pb, 40 + enc->extradata_size); /* size */
put_le32(pb, enc->width);
put_le32(pb, enc->height);
put_le16(pb, 1); /* planes */
put_le16(pb, enc->bits_per_sample ? enc->bits_per_sample : 24); /* depth */
/* compression type */
put_le32(pb, for_asf ? (enc->codec_tag ? enc->codec_tag : codec_get_asf_tag(tags, enc->codec_id)) : enc->codec_tag); //
put_le32(pb, enc->width * enc->height * 3);
put_le32(pb, 0);
put_le32(pb, 0);
put_le32(pb, 0);
put_le32(pb, 0);
put_buffer(pb, enc->extradata, enc->extradata_size);
if (enc->extradata_size & 1)
put_byte(pb, 0);
}
#endif //CONFIG_MUXERS
#ifdef CONFIG_DEMUXERS
/* We could be given one of the three possible structures here:
* WAVEFORMAT, PCMWAVEFORMAT or WAVEFORMATEX. Each structure
* is an expansion of the previous one with the fields added
* at the bottom. PCMWAVEFORMAT adds 'WORD wBitsPerSample' and
* WAVEFORMATEX adds 'WORD cbSize' and basically makes itself
* an openended structure.
*/
void get_wav_header(ByteIOContext *pb, AVCodecContext *codec, int size)
{
int id;
id = get_le16(pb);
codec->codec_type = CODEC_TYPE_AUDIO;
codec->codec_tag = id;
codec->channels = get_le16(pb);
codec->sample_rate = get_le32(pb);
codec->bit_rate = get_le32(pb) * 8;
codec->block_align = get_le16(pb);
if (size == 14) { /* We're dealing with plain vanilla WAVEFORMAT */
codec->bits_per_sample = 8;
}else
codec->bits_per_sample = get_le16(pb);
codec->codec_id = wav_codec_get_id(id, codec->bits_per_sample);
if (size > 16) { /* We're obviously dealing with WAVEFORMATEX */
codec->extradata_size = get_le16(pb);
if (codec->extradata_size > 0) {
if (codec->extradata_size > size - 18)
codec->extradata_size = size - 18;
codec->extradata = av_mallocz(codec->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
get_buffer(pb, codec->extradata, codec->extradata_size);
} else
codec->extradata_size = 0;
/* It is possible for the chunk to contain garbage at the end */
if (size - codec->extradata_size - 18 > 0)
url_fskip(pb, size - codec->extradata_size - 18);
}
}
int wav_codec_get_id(unsigned int tag, int bps)
{
int id;
id = codec_get_id(codec_wav_tags, tag);
if (id <= 0)
return id;
/* handle specific u8 codec */
if (id == CODEC_ID_PCM_S16LE && bps == 8)
id = CODEC_ID_PCM_U8;
if (id == CODEC_ID_PCM_S16LE && bps == 24)
id = CODEC_ID_PCM_S24LE;
if (id == CODEC_ID_PCM_S16LE && bps == 32)
id = CODEC_ID_PCM_S32LE;
return id;
}
#endif // CONFIG_DEMUXERS
void ff_parse_specific_params(AVCodecContext *stream, int *au_rate, int *au_ssize, int *au_scale)
{
int gcd;
*au_ssize= stream->block_align;
if(stream->frame_size && stream->sample_rate){
*au_scale=stream->frame_size;
*au_rate= stream->sample_rate;
}else if(stream->codec_type == CODEC_TYPE_VIDEO){
*au_scale= stream->time_base.num;
*au_rate = stream->time_base.den;
}else{
*au_scale= stream->block_align ? stream->block_align*8 : 8;
*au_rate = stream->bit_rate;
}
gcd= ff_gcd(*au_scale, *au_rate);
*au_scale /= gcd;
*au_rate /= gcd;
}