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  1. /*
  2.  * MPEG-2/4 AAC ADTS to MPEG-4 Audio Specific Configuration bitstream filter
  3.  * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
  4.  *
  5.  * This file is part of FFmpeg.
  6.  *
  7.  * FFmpeg is free software; you can redistribute it and/or
  8.  * modify it under the terms of the GNU Lesser General Public
  9.  * License as published by the Free Software Foundation; either
  10.  * version 2.1 of the License, or (at your option) any later version.
  11.  *
  12.  * FFmpeg is distributed in the hope that it will be useful,
  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15.  * Lesser General Public License for more details.
  16.  *
  17.  * You should have received a copy of the GNU Lesser General Public
  18.  * License along with FFmpeg; if not, write to the Free Software
  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20.  */
  21.  
  22. #include "avcodec.h"
  23. #include "aacadtsdec.h"
  24. #include "put_bits.h"
  25. #include "get_bits.h"
  26. #include "mpeg4audio.h"
  27. #include "internal.h"
  28.  
  29. typedef struct AACBSFContext {
  30.     int first_frame_done;
  31. } AACBSFContext;
  32.  
  33. /**
  34.  * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
  35.  * ADTS header and removes the ADTS header.
  36.  */
  37. static int aac_adtstoasc_filter(AVBitStreamFilterContext *bsfc,
  38.                                 AVCodecContext *avctx, const char *args,
  39.                                 uint8_t  **poutbuf, int *poutbuf_size,
  40.                                 const uint8_t *buf, int      buf_size,
  41.                                 int keyframe)
  42. {
  43.     GetBitContext gb;
  44.     PutBitContext pb;
  45.     AACADTSHeaderInfo hdr;
  46.  
  47.     AACBSFContext *ctx = bsfc->priv_data;
  48.  
  49.     init_get_bits(&gb, buf, AAC_ADTS_HEADER_SIZE*8);
  50.  
  51.     *poutbuf = (uint8_t*) buf;
  52.     *poutbuf_size = buf_size;
  53.  
  54.     if (avctx->extradata)
  55.         if (show_bits(&gb, 12) != 0xfff)
  56.             return 0;
  57.  
  58.     if (avpriv_aac_parse_header(&gb, &hdr) < 0) {
  59.         av_log(avctx, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
  60.         return -1;
  61.     }
  62.  
  63.     if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
  64.         avpriv_report_missing_feature(avctx,
  65.                                       "Multiple RDBs per frame with CRC");
  66.         return AVERROR_PATCHWELCOME;
  67.     }
  68.  
  69.     buf      += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
  70.     buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
  71.  
  72.     if (!ctx->first_frame_done) {
  73.         int            pce_size = 0;
  74.         uint8_t        pce_data[MAX_PCE_SIZE];
  75.         if (!hdr.chan_config) {
  76.             init_get_bits(&gb, buf, buf_size * 8);
  77.             if (get_bits(&gb, 3) != 5) {
  78.                 avpriv_report_missing_feature(avctx,
  79.                                               "PCE-based channel configuration "
  80.                                               "without PCE as first syntax "
  81.                                               "element");
  82.                 return AVERROR_PATCHWELCOME;
  83.             }
  84.             init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
  85.             pce_size = avpriv_copy_pce_data(&pb, &gb)/8;
  86.             flush_put_bits(&pb);
  87.             buf_size -= get_bits_count(&gb)/8;
  88.             buf      += get_bits_count(&gb)/8;
  89.         }
  90.         avctx->extradata_size = 2 + pce_size;
  91.         avctx->extradata = av_mallocz(avctx->extradata_size + FF_INPUT_BUFFER_PADDING_SIZE);
  92.  
  93.         init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
  94.         put_bits(&pb, 5, hdr.object_type);
  95.         put_bits(&pb, 4, hdr.sampling_index);
  96.         put_bits(&pb, 4, hdr.chan_config);
  97.         put_bits(&pb, 1, 0); //frame length - 1024 samples
  98.         put_bits(&pb, 1, 0); //does not depend on core coder
  99.         put_bits(&pb, 1, 0); //is not extension
  100.         flush_put_bits(&pb);
  101.         if (pce_size) {
  102.             memcpy(avctx->extradata + 2, pce_data, pce_size);
  103.         }
  104.  
  105.         ctx->first_frame_done = 1;
  106.     }
  107.  
  108.     *poutbuf = (uint8_t*) buf;
  109.     *poutbuf_size = buf_size;
  110.  
  111.     return 0;
  112. }
  113.  
  114. AVBitStreamFilter ff_aac_adtstoasc_bsf = {
  115.     .name           = "aac_adtstoasc",
  116.     .priv_data_size = sizeof(AACBSFContext),
  117.     .filter         = aac_adtstoasc_filter,
  118. };
  119.