FFmpeg/libavcodec/mpegaudiodecheader.c
Michael Niedermayer dd8ffc1925 Merge remote-tracking branch 'qatar/master'
* qatar/master: (47 commits)
  lavc: hide private symbols.
  lavc: deprecate img_get_alpha_info().
  lavc: use avpriv_ prefix for ff_toupper4.
  lavc: use avpriv_ prefix for ff_copy_bits and align_put_bits.
  lavc: use avpriv_ prefix for ff_ac3_parse_header.
  lavc: use avpriv_ prefix for ff_frame_rate_tab.
  lavc: rename ff_find_start_code to avpriv_mpv_find_start_code
  lavc: use avpriv_ prefix for ff_split_xiph_headers.
  lavc: use avpriv_ prefix for ff_dirac_parse_sequence_header.
  lavc: use avpriv_ prefix for some dv symbols used in lavf.
  lavc: use avpriv_ prefix for some flac symbols used in lavf.
  lavc: use avpriv_ prefix for some mpeg4audio symbols used in lavf.
  lavc: use avpriv_ prefix for some mpegaudio symbols used in lavf.
  lavc: use avpriv_ prefix for ff_aac_parse_header().
  lavf: hide private symbols.
  lavf: use avpriv_ prefix for some dv functions.
  lavf: use avpriv_ prefix for ff_new_chapter().
  avcodec: add CODEC_CAP_DELAY note to avcodec_decode_audio3() documentation
  avcodec: clarify the CODEC_CAP_DELAY note in avcodec_decode_video2()
  avcodec: clarify documentation of CODEC_CAP_DELAY
  ...

Conflicts:
	configure
	doc/general.texi
	libavcodec/Makefile
	libavcodec/aacdec.c
	libavcodec/allcodecs.c
	libavcodec/avcodec.h
	libavcodec/dv.c
	libavcodec/dvdata.c
	libavcodec/dvdata.h
	libavcodec/libspeexenc.c
	libavcodec/mpegvideo.c
	libavcodec/version.h
	libavformat/avidec.c
	libavformat/dv.c
	libavformat/dv.h
	libavformat/flvenc.c
	libavformat/mov.c
	libavformat/mp3enc.c
	libavformat/oggparsespeex.c

Merged-by: Michael Niedermayer <michaelni@gmx.at>
2011-10-21 02:01:26 +02:00

148 lines
4.1 KiB
C

/*
* MPEG Audio header decoder
* Copyright (c) 2001, 2002 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
*/
/**
* @file
* MPEG Audio header decoder.
*/
//#define DEBUG
#include "avcodec.h"
#include "mpegaudio.h"
#include "mpegaudiodata.h"
#include "mpegaudiodecheader.h"
int avpriv_mpegaudio_decode_header(MPADecodeHeader *s, uint32_t header)
{
int sample_rate, frame_size, mpeg25, padding;
int sample_rate_index, bitrate_index;
if (header & (1<<20)) {
s->lsf = (header & (1<<19)) ? 0 : 1;
mpeg25 = 0;
} else {
s->lsf = 1;
mpeg25 = 1;
}
s->layer = 4 - ((header >> 17) & 3);
/* extract frequency */
sample_rate_index = (header >> 10) & 3;
sample_rate = avpriv_mpa_freq_tab[sample_rate_index] >> (s->lsf + mpeg25);
sample_rate_index += 3 * (s->lsf + mpeg25);
s->sample_rate_index = sample_rate_index;
s->error_protection = ((header >> 16) & 1) ^ 1;
s->sample_rate = sample_rate;
bitrate_index = (header >> 12) & 0xf;
padding = (header >> 9) & 1;
//extension = (header >> 8) & 1;
s->mode = (header >> 6) & 3;
s->mode_ext = (header >> 4) & 3;
//copyright = (header >> 3) & 1;
//original = (header >> 2) & 1;
//emphasis = header & 3;
if (s->mode == MPA_MONO)
s->nb_channels = 1;
else
s->nb_channels = 2;
if (bitrate_index != 0) {
frame_size = avpriv_mpa_bitrate_tab[s->lsf][s->layer - 1][bitrate_index];
s->bit_rate = frame_size * 1000;
switch(s->layer) {
case 1:
frame_size = (frame_size * 12000) / sample_rate;
frame_size = (frame_size + padding) * 4;
break;
case 2:
frame_size = (frame_size * 144000) / sample_rate;
frame_size += padding;
break;
default:
case 3:
frame_size = (frame_size * 144000) / (sample_rate << s->lsf);
frame_size += padding;
break;
}
s->frame_size = frame_size;
} else {
/* if no frame size computed, signal it */
return 1;
}
#if defined(DEBUG)
av_dlog(NULL, "layer%d, %d Hz, %d kbits/s, ",
s->layer, s->sample_rate, s->bit_rate);
if (s->nb_channels == 2) {
if (s->layer == 3) {
if (s->mode_ext & MODE_EXT_MS_STEREO)
av_dlog(NULL, "ms-");
if (s->mode_ext & MODE_EXT_I_STEREO)
av_dlog(NULL, "i-");
}
av_dlog(NULL, "stereo");
} else {
av_dlog(NULL, "mono");
}
av_dlog(NULL, "\n");
#endif
return 0;
}
int avpriv_mpa_decode_header(AVCodecContext *avctx, uint32_t head, int *sample_rate, int *channels, int *frame_size, int *bit_rate)
{
MPADecodeHeader s1, *s = &s1;
if (ff_mpa_check_header(head) != 0)
return -1;
if (avpriv_mpegaudio_decode_header(s, head) != 0) {
return -1;
}
switch(s->layer) {
case 1:
avctx->codec_id = CODEC_ID_MP1;
*frame_size = 384;
break;
case 2:
avctx->codec_id = CODEC_ID_MP2;
*frame_size = 1152;
break;
default:
case 3:
avctx->codec_id = CODEC_ID_MP3;
if (s->lsf)
*frame_size = 576;
else
*frame_size = 1152;
break;
}
*sample_rate = s->sample_rate;
*channels = s->nb_channels;
*bit_rate = s->bit_rate;
avctx->sub_id = s->layer;
return s->frame_size;
}