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/mpeg4audio.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     int pce_size;
  36     uint8_t pce_data[MAX_PCE_SIZE];
  37 } ADTSContext;
  38
  39 static int decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
  40 {
  41     GetBitContext gb;
  42     PutBitContext pb;
  43
  44     init_get_bits(&gb, buf, size * 8);
  45     adts->objecttype = get_bits(&gb, 5) - 1;
  46     adts->sample_rate_index = get_bits(&gb, 4);
  47     adts->channel_conf = get_bits(&gb, 4);
  48
  49     if (adts->objecttype > 3U) {
  50         av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
  51         return -1;
  52     }
  53     if (adts->sample_rate_index == 15) {
  54         av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
  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         av_log(s, AV_LOG_ERROR, "Signaled SBR or PS is not supported\n");
  67         return -1;
  68     }
  69     if (!adts->channel_conf) {
  70         init_put_bits(&pb, adts->pce_data, MAX_PCE_SIZE);
  71
  72         put_bits(&pb, 3, 5); //ID_PCE
  73         adts->pce_size = (ff_copy_pce_data(&pb, &gb) + 3) / 8;
  74         flush_put_bits(&pb);
  75     }
  76
  77     adts->write_adts = 1;
  78
  79     return 0;
  80 }
  81
  82 static int adts_write_header(AVFormatContext *s)
  83 {
  84     ADTSContext *adts = s->priv_data;
  85     AVCodecContext *avc = s->streams[0]->codec;
  86
  87     if(avc->extradata_size > 0 &&
  88             decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
  89         return -1;
  90
  91     return 0;
  92 }
  93
  94 static int adts_write_frame_header(AVFormatContext *s, int size)
  95 {
  96     ADTSContext *ctx = s->priv_data;
  97     PutBitContext pb;
  98     uint8_t buf[ADTS_HEADER_SIZE];
  99
 100     init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
 101
 102     /* adts_fixed_header */
 103     put_bits(&pb, 12, 0xfff);   /* syncword */
 104     put_bits(&pb, 1, 0);        /* ID */
 105     put_bits(&pb, 2, 0);        /* layer */
 106     put_bits(&pb, 1, 1);        /* protection_absent */
 107     put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
 108     put_bits(&pb, 4, ctx->sample_rate_index);
 109     put_bits(&pb, 1, 0);        /* private_bit */
 110     put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
 111     put_bits(&pb, 1, 0);        /* original_copy */
 112     put_bits(&pb, 1, 0);        /* home */
 113
 114     /* adts_variable_header */
 115     put_bits(&pb, 1, 0);        /* copyright_identification_bit */
 116     put_bits(&pb, 1, 0);        /* copyright_identification_start */
 117     put_bits(&pb, 13, ADTS_HEADER_SIZE + size + ctx->pce_size); /* aac_frame_length */
 118     put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
 119     put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
 120
 121     flush_put_bits(&pb);
 122     put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
 123     if (ctx->pce_size) {
 124         put_buffer(s->pb, ctx->pce_data, ctx->pce_size);
 125         ctx->pce_size = 0;
 126     }
 127
 128     return 0;
 129 }
 130
 131 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
 132 {
 133     ADTSContext *adts = s->priv_data;
 134     ByteIOContext *pb = s->pb;
 135
 136     if (!pkt->size)
 137         return 0;
 138     if(adts->write_adts)
 139         adts_write_frame_header(s, pkt->size);
 140     put_buffer(pb, pkt->data, pkt->size);
 141     put_flush_packet(pb);
 142
 143     return 0;
 144 }
 145
 146 AVOutputFormat adts_muxer = {
 147     "adts",
 148     NULL_IF_CONFIG_SMALL("ADTS AAC"),
 149     "audio/aac",
 150     "aac,adts",
 151     sizeof(ADTSContext),
 152     CODEC_ID_AAC,
 153     CODEC_ID_NONE,
 154     adts_write_header,
 155     adts_write_packet,
 156 };