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libavcodec/aac_adtstoasc_bsf.c

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00001 /*
00002  * MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration bitstream filter
00003  * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00022 #include "avcodec.h"
00023 #include "aac_parser.h"
00024 #include "put_bits.h"
00025 #include "get_bits.h"
00026 #include "mpeg4audio.h"
00027 #include "internal.h"
00028 
00029 typedef struct AACBSFContext {
00030     int first_frame_done;
00031 } AACBSFContext;
00032 
00037 static int aac_adtstoasc_filter(AVBitStreamFilterContext *bsfc,
00038                                 AVCodecContext *avctx, const char *args,
00039                                 uint8_t  **poutbuf, int *poutbuf_size,
00040                                 const uint8_t *buf, int      buf_size,
00041                                 int keyframe)
00042 {
00043     GetBitContext gb;
00044     PutBitContext pb;
00045     AACADTSHeaderInfo hdr;
00046 
00047     AACBSFContext *ctx = bsfc->priv_data;
00048 
00049     init_get_bits(&gb, buf, AAC_ADTS_HEADER_SIZE*8);
00050 
00051     *poutbuf = (uint8_t*) buf;
00052     *poutbuf_size = buf_size;
00053 
00054     if (avctx->extradata)
00055         if (show_bits(&gb, 12) != 0xfff)
00056             return 0;
00057 
00058     if (ff_aac_parse_header(&gb, &hdr) < 0) {
00059         av_log(avctx, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
00060         return -1;
00061     }
00062 
00063     if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
00064         av_log_missing_feature(avctx, "Multiple RDBs per frame with CRC is", 0);
00065         return -1;
00066     }
00067 
00068     buf      += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
00069     buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
00070 
00071     if (!ctx->first_frame_done) {
00072         int            pce_size = 0;
00073         uint8_t        pce_data[MAX_PCE_SIZE];
00074         if (!hdr.chan_config) {
00075             init_get_bits(&gb, buf, buf_size);
00076             if (get_bits(&gb, 3) != 5) {
00077                 av_log_missing_feature(avctx, "PCE based channel configuration, where the PCE is not the first syntax element is", 0);
00078                 return -1;
00079             }
00080             init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
00081             pce_size = ff_copy_pce_data(&pb, &gb)/8;
00082             flush_put_bits(&pb);
00083             buf_size -= get_bits_count(&gb)/8;
00084             buf      += get_bits_count(&gb)/8;
00085         }
00086         avctx->extradata_size = 2 + pce_size;
00087         avctx->extradata = av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
00088 
00089         init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
00090         put_bits(&pb, 5, hdr.object_type);
00091         put_bits(&pb, 4, hdr.sampling_index);
00092         put_bits(&pb, 4, hdr.chan_config);
00093         put_bits(&pb, 1, 0); //frame length - 1024 samples
00094         put_bits(&pb, 1, 0); //does not depend on core coder
00095         put_bits(&pb, 1, 0); //is not extension
00096         flush_put_bits(&pb);
00097         if (pce_size) {
00098             memcpy(avctx->extradata + 2, pce_data, pce_size);
00099         }
00100 
00101         ctx->first_frame_done = 1;
00102     }
00103 
00104     *poutbuf = (uint8_t*) buf;
00105     *poutbuf_size = buf_size;
00106 
00107     return 0;
00108 }
00109 
00110 AVBitStreamFilter aac_adtstoasc_bsf = {
00111     "aac_adtstoasc",
00112     sizeof(AACBSFContext),
00113     aac_adtstoasc_filter,
00114 };

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