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/get_bits.h"
  24 #include "libavcodec/put_bits.h"
  25 #include "libavcodec/internal.h"
  26 #include "avformat.h"
  27
  28 #define ADTS_HEADER_SIZE 7
  29
  30 typedef struct {
  31     int write_adts;
  32     int objecttype;
  33     int sample_rate_index;
  34     int channel_conf;
  35 } ADTSContext;
  36
  37 static int decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
  38 {
  39     GetBitContext gb;
  40
  41     init_get_bits(&gb, buf, size * 8);
  42     adts->objecttype = get_bits(&gb, 5) - 1;
  43     adts->sample_rate_index = get_bits(&gb, 4);
  44     adts->channel_conf = get_bits(&gb, 4);
  45
  46     if (adts->objecttype > 3U) {
  47         av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
  48         return -1;
  49     }
  50     if (adts->sample_rate_index == 15) {
  51         av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
  52         return -1;
  53     }
  54     if (adts->channel_conf == 0) {
  55         ff_log_missing_feature(s, "PCE based channel configuration", 0);
  56         return -1;
  57     }
  58     if (get_bits(&gb, 1)) {
  59         av_log(s, AV_LOG_ERROR, "960/120 MDCT window is not allowed in ADTS\n");
  60         return -1;
  61     }
  62     if (get_bits(&gb, 1)) {
  63         av_log(s, AV_LOG_ERROR, "Scalable configurations are not allowed in ADTS\n");
  64         return -1;
  65     }
  66     if (get_bits(&gb, 1)) {
  67         ff_log_missing_feature(s, "Signaled SBR or PS", 0);
  68         return -1;
  69     }
  70
  71     adts->write_adts = 1;
  72
  73     return 0;
  74 }
  75
  76 static int adts_write_header(AVFormatContext *s)
  77 {
  78     ADTSContext *adts = s->priv_data;
  79     AVCodecContext *avc = s->streams[0]->codec;
  80
  81     if(avc->extradata_size > 0 &&
  82             decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
  83         return -1;
  84
  85     return 0;
  86 }
  87
  88 static int adts_write_frame_header(AVFormatContext *s, int size)
  89 {
  90     ADTSContext *ctx = s->priv_data;
  91     PutBitContext pb;
  92     uint8_t buf[ADTS_HEADER_SIZE];
  93
  94     init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
  95
  96     /* adts_fixed_header */
  97     put_bits(&pb, 12, 0xfff);   /* syncword */
  98     put_bits(&pb, 1, 0);        /* ID */
  99     put_bits(&pb, 2, 0);        /* layer */
 100     put_bits(&pb, 1, 1);        /* protection_absent */
 101     put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
 102     put_bits(&pb, 4, ctx->sample_rate_index);
 103     put_bits(&pb, 1, 0);        /* private_bit */
 104     put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
 105     put_bits(&pb, 1, 0);        /* original_copy */
 106     put_bits(&pb, 1, 0);        /* home */
 107
 108     /* adts_variable_header */
 109     put_bits(&pb, 1, 0);        /* copyright_identification_bit */
 110     put_bits(&pb, 1, 0);        /* copyright_identification_start */
 111     put_bits(&pb, 13, ADTS_HEADER_SIZE + size); /* aac_frame_length */
 112     put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
 113     put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
 114
 115     flush_put_bits(&pb);
 116     put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
 117
 118     return 0;
 119 }
 120
 121 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
 122 {
 123     ADTSContext *adts = s->priv_data;
 124     ByteIOContext *pb = s->pb;
 125
 126     if (!pkt->size)
 127         return 0;
 128     if(adts->write_adts)
 129         adts_write_frame_header(s, pkt->size);
 130     put_buffer(pb, pkt->data, pkt->size);
 131     put_flush_packet(pb);
 132
 133     return 0;
 134 }
 135
 136 AVOutputFormat adts_muxer = {
 137     "adts",
 138     NULL_IF_CONFIG_SMALL("ADTS AAC"),
 139     "audio/aac",
 140     "aac",
 141     sizeof(ADTSContext),
 142     CODEC_ID_AAC,
 143     CODEC_ID_NONE,
 144     adts_write_header,
 145     adts_write_packet,
 146 };