From 3cac899af968f9963241c0d0236a16d70eb6b06d Mon Sep 17 00:00:00 2001 From: Alex Converse Date: Mon, 12 Jul 2010 18:52:03 +0000 Subject: Split the ADTS header decoder off of the ADTS parser. 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 --- libavcodec/aacadtsdec.c | 70 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) create mode 100644 libavcodec/aacadtsdec.c (limited to 'libavcodec/aacadtsdec.c') diff --git a/libavcodec/aacadtsdec.c b/libavcodec/aacadtsdec.c new file mode 100644 index 0000000000..fd86d288a6 --- /dev/null +++ b/libavcodec/aacadtsdec.c @@ -0,0 +1,70 @@ +/* + * 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; +} -- cgit v1.2.3