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Split the ADTS header decoder off of the ADTS parser.

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The AAC decoder and ADTS-to-ASC BSF both require the header decoder
but not full parsing capabilities.

Originally committed as revision 24217 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Alex Converse
2010-07-12 18:52:03 +00:00
parent 65415bb93a
commit 3cac899af9
8 changed files with 84 additions and 59 deletions
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70
libavcodec/aacadtsdec.c Normal file
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/*
* Audio and Video frame extraction
* Copyright (c) 2003 Fabrice Bellard
* Copyright (c) 2003 Michael Niedermayer
* Copyright (c) 2009 Alex Converse
*
* 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 "aac_ac3_parser.h"
#include "aacadtsdec.h"
#include "get_bits.h"
#include "mpeg4audio.h"
int ff_aac_parse_header(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
{
int size, rdb, ch, sr;
int aot, crc_abs;
if(get_bits(gbc, 12) != 0xfff)
return AAC_AC3_PARSE_ERROR_SYNC;
skip_bits1(gbc); /* id */
skip_bits(gbc, 2); /* layer */
crc_abs = get_bits1(gbc); /* protection_absent */
aot = get_bits(gbc, 2); /* profile_objecttype */
sr = get_bits(gbc, 4); /* sample_frequency_index */
if(!ff_mpeg4audio_sample_rates[sr])
return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
skip_bits1(gbc); /* private_bit */
ch = get_bits(gbc, 3); /* channel_configuration */
skip_bits1(gbc); /* original/copy */
skip_bits1(gbc); /* home */
/* adts_variable_header */
skip_bits1(gbc); /* copyright_identification_bit */
skip_bits1(gbc); /* copyright_identification_start */
size = get_bits(gbc, 13); /* aac_frame_length */
if(size < AAC_ADTS_HEADER_SIZE)
return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
skip_bits(gbc, 11); /* adts_buffer_fullness */
rdb = get_bits(gbc, 2); /* number_of_raw_data_blocks_in_frame */
hdr->object_type = aot + 1;
hdr->chan_config = ch;
hdr->crc_absent = crc_abs;
hdr->num_aac_frames = rdb + 1;
hdr->sampling_index = sr;
hdr->sample_rate = ff_mpeg4audio_sample_rates[sr];
hdr->samples = (rdb + 1) * 1024;
hdr->bit_rate = size * 8 * hdr->sample_rate / hdr->samples;
return size;
}