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/avcodec.h"
  26 #include "libavcodec/mpeg4audio.h"
  27 #include "avformat.h"
  28
  29 #define ADTS_HEADER_SIZE 7
  30
  31 typedef struct {
  32     int write_adts;
  33     int objecttype;
  34     int sample_rate_index;
  35     int channel_conf;
  36     int pce_size;
  37     uint8_t pce_data[MAX_PCE_SIZE];
  38 } ADTSContext;
  39
  40 static int decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)
  41 {
  42     GetBitContext gb;
  43     PutBitContext pb;
  44
  45     init_get_bits(&gb, buf, size * 8);
  46     adts->objecttype = get_bits(&gb, 5) - 1;
  47     adts->sample_rate_index = get_bits(&gb, 4);
  48     adts->channel_conf = get_bits(&gb, 4);
  49
  50     if (adts->objecttype > 3U) {
  51         av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
  52         return -1;
  53     }
  54     if (adts->sample_rate_index == 15) {
  55         av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
  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         av_log_missing_feature(s, "Signaled SBR or PS", 0);
  68         return -1;
  69     }
  70     if (!adts->channel_conf) {
  71         init_put_bits(&pb, adts->pce_data, MAX_PCE_SIZE);
  72
  73         put_bits(&pb, 3, 5); //ID_PCE
  74         adts->pce_size = (ff_copy_pce_data(&pb, &gb) + 3) / 8;
  75         flush_put_bits(&pb);
  76     }
  77
  78     adts->write_adts = 1;
  79
  80     return 0;
  81 }
  82
  83 static int adts_write_header(AVFormatContext *s)
  84 {
  85     ADTSContext *adts = s->priv_data;
  86     AVCodecContext *avc = s->streams[0]->codec;
  87
  88     if(avc->extradata_size > 0 &&
  89             decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
  90         return -1;
  91
  92     return 0;
  93 }
  94
  95 static int adts_write_frame_header(AVFormatContext *s, int size)
  96 {
  97     ADTSContext *ctx = s->priv_data;
  98     PutBitContext pb;
  99     uint8_t buf[ADTS_HEADER_SIZE];
 100
 101     init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
 102
 103     /* adts_fixed_header */
 104     put_bits(&pb, 12, 0xfff);   /* syncword */
 105     put_bits(&pb, 1, 0);        /* ID */
 106     put_bits(&pb, 2, 0);        /* layer */
 107     put_bits(&pb, 1, 1);        /* protection_absent */
 108     put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
 109     put_bits(&pb, 4, ctx->sample_rate_index);
 110     put_bits(&pb, 1, 0);        /* private_bit */
 111     put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
 112     put_bits(&pb, 1, 0);        /* original_copy */
 113     put_bits(&pb, 1, 0);        /* home */
 114
 115     /* adts_variable_header */
 116     put_bits(&pb, 1, 0);        /* copyright_identification_bit */
 117     put_bits(&pb, 1, 0);        /* copyright_identification_start */
 118     put_bits(&pb, 13, ADTS_HEADER_SIZE + size + ctx->pce_size); /* aac_frame_length */
 119     put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
 120     put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
 121
 122     flush_put_bits(&pb);
 123     put_buffer(s->pb, buf, ADTS_HEADER_SIZE);
 124     if (ctx->pce_size) {
 125         put_buffer(s->pb, ctx->pce_data, ctx->pce_size);
 126         ctx->pce_size = 0;
 127     }
 128
 129     return 0;
 130 }
 131
 132 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
 133 {
 134     ADTSContext *adts = s->priv_data;
 135     ByteIOContext *pb = s->pb;
 136
 137     if (!pkt->size)
 138         return 0;
 139     if(adts->write_adts)
 140         adts_write_frame_header(s, pkt->size);
 141     put_buffer(pb, pkt->data, pkt->size);
 142     put_flush_packet(pb);
 143
 144     return 0;
 145 }
 146
 147 AVOutputFormat adts_muxer = {
 148     "adts",
 149     NULL_IF_CONFIG_SMALL("ADTS AAC"),
 150     "audio/aac",
 151     "aac,adts",
 152     sizeof(ADTSContext),
 153     CODEC_ID_AAC,
 154     CODEC_ID_NONE,
 155     adts_write_header,
 156     adts_write_packet,
 157 };