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Member "ffmpeg-3.4.2/libavcodec/aac_adtstoasc_bsf.c" (12 Feb 2018, 5133 Bytes) of package /linux/misc/ffmpeg-3.4.2.tar.xz:


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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 "bsf.h"
   25 #include "put_bits.h"
   26 #include "get_bits.h"
   27 #include "mpeg4audio.h"
   28 #include "internal.h"
   29 
   30 typedef struct AACBSFContext {
   31     int first_frame_done;
   32 } AACBSFContext;
   33 
   34 /**
   35  * This filter creates an MPEG-4 AudioSpecificConfig from an MPEG-2/4
   36  * ADTS header and removes the ADTS header.
   37  */
   38 static int aac_adtstoasc_filter(AVBSFContext *bsfc, AVPacket *out)
   39 {
   40     AACBSFContext *ctx = bsfc->priv_data;
   41 
   42     GetBitContext gb;
   43     PutBitContext pb;
   44     AACADTSHeaderInfo hdr;
   45     AVPacket *in;
   46     int ret;
   47 
   48     ret = ff_bsf_get_packet(bsfc, &in);
   49     if (ret < 0)
   50         return ret;
   51 
   52     if (bsfc->par_in->extradata && in->size >= 2 && (AV_RB16(in->data) >> 4) != 0xfff)
   53         goto finish;
   54 
   55     if (in->size < AAC_ADTS_HEADER_SIZE)
   56         goto packet_too_small;
   57 
   58     init_get_bits(&gb, in->data, AAC_ADTS_HEADER_SIZE * 8);
   59 
   60     if (avpriv_aac_parse_header(&gb, &hdr) < 0) {
   61         av_log(bsfc, AV_LOG_ERROR, "Error parsing ADTS frame header!\n");
   62         ret = AVERROR_INVALIDDATA;
   63         goto fail;
   64     }
   65 
   66     if (!hdr.crc_absent && hdr.num_aac_frames > 1) {
   67         avpriv_report_missing_feature(bsfc,
   68                                       "Multiple RDBs per frame with CRC");
   69         ret = AVERROR_PATCHWELCOME;
   70         goto fail;
   71     }
   72 
   73     in->size -= AAC_ADTS_HEADER_SIZE + 2 * !hdr.crc_absent;
   74     if (in->size <= 0)
   75         goto packet_too_small;
   76     in->data += AAC_ADTS_HEADER_SIZE + 2 * !hdr.crc_absent;
   77 
   78     if (!ctx->first_frame_done) {
   79         int            pce_size = 0;
   80         uint8_t        pce_data[MAX_PCE_SIZE];
   81         uint8_t       *extradata;
   82 
   83         if (!hdr.chan_config) {
   84             init_get_bits(&gb, in->data, in->size * 8);
   85             if (get_bits(&gb, 3) != 5) {
   86                 avpriv_report_missing_feature(bsfc,
   87                                               "PCE-based channel configuration "
   88                                               "without PCE as first syntax "
   89                                               "element");
   90                 ret = AVERROR_PATCHWELCOME;
   91                 goto fail;
   92             }
   93             init_put_bits(&pb, pce_data, MAX_PCE_SIZE);
   94             pce_size = avpriv_copy_pce_data(&pb, &gb)/8;
   95             flush_put_bits(&pb);
   96             in->size -= get_bits_count(&gb)/8;
   97             in->data += get_bits_count(&gb)/8;
   98         }
   99 
  100         extradata = av_packet_new_side_data(in, AV_PKT_DATA_NEW_EXTRADATA,
  101                                             2 + pce_size);
  102         if (!extradata) {
  103             ret = AVERROR(ENOMEM);
  104             goto fail;
  105         }
  106 
  107         init_put_bits(&pb, extradata, 2 + pce_size);
  108         put_bits(&pb, 5, hdr.object_type);
  109         put_bits(&pb, 4, hdr.sampling_index);
  110         put_bits(&pb, 4, hdr.chan_config);
  111         put_bits(&pb, 1, 0); //frame length - 1024 samples
  112         put_bits(&pb, 1, 0); //does not depend on core coder
  113         put_bits(&pb, 1, 0); //is not extension
  114         flush_put_bits(&pb);
  115         if (pce_size) {
  116             memcpy(extradata + 2, pce_data, pce_size);
  117         }
  118 
  119         ctx->first_frame_done = 1;
  120     }
  121 
  122 finish:
  123     av_packet_move_ref(out, in);
  124     av_packet_free(&in);
  125 
  126     return 0;
  127 
  128 packet_too_small:
  129     av_log(bsfc, AV_LOG_ERROR, "Input packet too small\n");
  130     ret = AVERROR_INVALIDDATA;
  131 fail:
  132     av_packet_free(&in);
  133     return ret;
  134 }
  135 
  136 static int aac_adtstoasc_init(AVBSFContext *ctx)
  137 {
  138     /* Validate the extradata if the stream is already MPEG-4 AudioSpecificConfig */
  139     if (ctx->par_in->extradata) {
  140         MPEG4AudioConfig mp4ac;
  141         int ret = avpriv_mpeg4audio_get_config(&mp4ac, ctx->par_in->extradata,
  142                                                ctx->par_in->extradata_size * 8, 1);
  143         if (ret < 0) {
  144             av_log(ctx, AV_LOG_ERROR, "Error parsing AudioSpecificConfig extradata!\n");
  145             return ret;
  146         }
  147     }
  148 
  149     return 0;
  150 }
  151 
  152 static const enum AVCodecID codec_ids[] = {
  153     AV_CODEC_ID_AAC, AV_CODEC_ID_NONE,
  154 };
  155 
  156 const AVBitStreamFilter ff_aac_adtstoasc_bsf = {
  157     .name           = "aac_adtstoasc",
  158     .priv_data_size = sizeof(AACBSFContext),
  159     .init           = aac_adtstoasc_init,
  160     .filter         = aac_adtstoasc_filter,
  161     .codec_ids      = codec_ids,
  162 };