FFmpeg/libavcodec/mpegaudiodecheader.c
Michael Niedermayer 2af8f2cea6 Merge remote-tracking branch 'qatar/master'
* qatar/master: (27 commits)
  cmdutils: use new avcodec_is_decoder/encoder() functions.
  lavc: make codec_is_decoder/encoder() public.
  lavc: deprecate AVCodecContext.sub_id.
  libcdio: add a forgotten AVClass to the private context.
  swscale: remove "cpu flags" from -sws_flags description.
  proresenc: give user a possibility to alter some encoding parameters
  vorbisenc: add output buffer overwrite protection
  libopencore-amrnbenc: fix end-of-stream handling
  ra144enc: fix end-of-stream handling
  nellymoserenc: zero any leftover packet bytes
  nellymoserenc: use proper MDCT overlap delay
  qpeg: Use bytestream2 functions to prevent buffer overreads.
  swscale: make %rep unconditional.
  vp8: convert simple loopfilter x86 assembly to use named arguments.
  vp8: convert idct x86 assembly to use named arguments.
  vp8: convert mc x86 assembly to use named arguments.
  vp8: convert loopfilter x86 assembly to use cpuflags().
  vp8: convert idct/mc x86 assembly to use cpuflags().
  swscale: remove now unnecessary hack.
  x86inc: don't "bake" stack_offset in named arguments.
  ...

Conflicts:
	cmdutils.c
	doc/APIchanges
	libavcodec/mpeg12.c
	libavcodec/options.c
	libavcodec/qpeg.c
	libavcodec/utils.c
	libavcodec/version.h
	libavdevice/libcdio.c
	tests/lavf-regression.sh

Merged-by: Michael Niedermayer <michaelni@gmx.at>
2012-03-05 00:15:55 +01:00

147 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;
return s->frame_size;
}