libavformat/adtsenc.c

   1 /*
   2  * ADTS muxer.
   3  * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>
   4  *                    Mans Rullgard <mans@mansr.com>
   5  *
   6  * This file is part of FFmpeg.
   7  *
   8  * FFmpeg is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * FFmpeg is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with FFmpeg; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23 #include "libavcodec/bitstream.h"
  24 #include "libavcodec/internal.h"
  25 #include "avformat.h"
  26
  27 #define ADTS_HEADER_SIZE 7
  28
  29 typedef struct {
  30     int write_adts;
  31     int objecttype;
  32     int sample_rate_index;
  33     int channel_conf;
  34 } ADTSContext;
  35
  36 static int decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
  37 {
  38     GetBitContext gb;
  39
  40     init_get_bits(&gb, buf, size * 8);
  41     adts->objecttype = get_bits(&gb, 5) - 1;
  42     adts->sample_rate_index = get_bits(&gb, 4);
  43     adts->channel_conf = get_bits(&gb, 4);
  44
  45     if (adts->objecttype > 3U) {
  46         av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
  47         return -1;
  48     }
  49     if (adts->sample_rate_index == 15) {
  50         av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
  51         return -1;
  52     }
  53     if (adts->channel_conf == 0) {
  54         ff_log_missing_feature(s, "PCE based channel configuration", 0);
  55         return -1;
  56     }
  57     if (get_bits(&gb, 1)) {
  58         av_log(s, AV_LOG_ERROR, "960/120 MDCT window is not allowed in ADTS\n");
  59         return -1;
  60     }
  61     if (get_bits(&gb, 1)) {
  62         av_log(s, AV_LOG_ERROR, "Scalable configurations are not allowed in ADTS\n");
  63         return -1;
  64     }
  65     if (get_bits(&gb, 1)) {
  66         ff_log_missing_feature(s, "Signaled SBR or PS", 0);
  67         return -1;
  68     }
  69
  70     adts->write_adts = 1;
  71
  72     return 0;
  73 }
  74
  75 static int adts_write_header(AVFormatContext *s)
  76 {
  77     ADTSContext *adts = s->priv_data;
  78     AVCodecContext *avc = s->streams[0]->codec;
  79
  80     if(avc->extradata_size > 0 &&
  81             decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
  82         return -1;
  83
  84     return 0;
  85 }
  86
  87 static int adts_write_frame_header(AVFormatContext *s, int size)
  88 {
  89     ADTSContext *ctx = s->priv_data;
  90     PutBitContext pb;
  91     uint8_t buf[ADTS_HEADER_SIZE];
  92
  93     init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
  94
  95     /* adts_fixed_header */
  96     put_bits(&pb, 12, 0xfff);   /* syncword */
  97     put_bits(&pb, 1, 0);        /* ID */
  98     put_bits(&pb, 2, 0);        /* layer */
  99     put_bits(&pb, 1, 1);        /* protection_absent */
 100     put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
 101     put_bits(&pb, 4, ctx->sample_rate_index);
 102     put_bits(&pb, 1, 0);        /* private_bit */
 103     put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
 104     put_bits(&pb, 1, 0);        /* original_copy */
 105     put_bits(&pb, 1, 0);        /* home */
 106
 107     /* adts_variable_header */
 108     put_bits(&pb, 1, 0);        /* copyright_identification_bit */
 109     put_bits(&pb, 1, 0);        /* copyright_identification_start */
 110     put_bits(&pb, 13, ADTS_HEADER_SIZE + size); /* aac_frame_length */
 111     put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
 112     put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
 113
 114     flush_put_bits(&pb);
 115     put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
 116
 117     return 0;
 118 }
 119
 120 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
 121 {
 122     ADTSContext *adts = s->priv_data;
 123     ByteIOContext *pb = s->pb;
 124
 125     if (!pkt->size)
 126         return 0;
 127     if(adts->write_adts)
 128         adts_write_frame_header(s, pkt->size);
 129     put_buffer(pb, pkt->data, pkt->size);
 130     put_flush_packet(pb);
 131
 132     return 0;
 133 }
 134
 135 AVOutputFormat adts_muxer = {
 136     "adts",
 137     NULL_IF_CONFIG_SMALL("ADTS AAC"),
 138     "audio/aac",
 139     "aac",
 140     sizeof(ADTSContext),
 141     CODEC_ID_AAC,
 142     CODEC_ID_NONE,
 143     adts_write_header,
 144     adts_write_packet,
 145 };