libavcodec/aac_adtstoasc_bsf.c

   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 "aac_parser.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 (ff_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         av_log_missing_feature(avctx, "Multiple RDBs per frame with CRC is", 0);
  65         return -1;
  66     }
  67
  68     buf      += AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
  69     buf_size -= AAC_ADTS_HEADER_SIZE + 2*!hdr.crc_absent;
  70
  71     if (!ctx->first_frame_done) {
  72         int            pce_size = 0;
  73         uint8_t        pce_data[MAX_PCE_SIZE];
  74         if (!hdr.chan_config) {
  75             init_get_bits(&gb, buf, buf_size);
  76             if (get_bits(&gb, 3) != 5) {
  77                 av_log_missing_feature(avctx, "PCE based channel configuration, where the PCE is not the first syntax element is", 0);
  78                 return -1;
  79             }
  80             init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
  81             pce_size = ff_copy_pce_data(&pb, &gb)/8;
  82             flush_put_bits(&pb);
  83             buf_size -= get_bits_count(&gb)/8;
  84             buf      += get_bits_count(&gb)/8;
  85         }
  86         avctx->extradata_size = 2 + pce_size;
  87         avctx->extradata = av_malloc(avctx->extradata_size);
  88
  89         init_put_bits(&pb, avctx->extradata, avctx->extradata_size);
  90         put_bits(&pb, 5, hdr.object_type);
  91         put_bits(&pb, 4, hdr.sampling_index);
  92         put_bits(&pb, 4, hdr.chan_config);
  93         put_bits(&pb, 1, 0); //frame length - 1024 samples
  94         put_bits(&pb, 1, 0); //does not depend on core coder
  95         put_bits(&pb, 1, 0); //is not extension
  96         flush_put_bits(&pb);
  97         if (pce_size) {
  98             memcpy(avctx->extradata + 2, pce_data, pce_size);
  99         }
 100
 101         ctx->first_frame_done = 1;
 102     }
 103
 104     *poutbuf = (uint8_t*) buf;
 105     *poutbuf_size = buf_size;
 106
 107     return 0;
 108 }
 109
 110 AVBitStreamFilter aac_adtstoasc_bsf = {
 111     "aac_adtstoasc",
 112     sizeof(AACBSFContext),
 113     aac_adtstoasc_filter,
 114 };