/*
  * ADTS muxer.
  * Copyright (c) 2006 Baptiste Coudurier <baptiste.coudurier@smartjog.com>

  *                    Mans Rullgard <mans@mansr.com>

  *

  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or

  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either

  * version 2.1 of the License, or (at your option) any later version.

  *

  * FFmpeg is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public

  * License along with FFmpeg; if not, write to the Free Software

  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 
 #include "libavcodec/bitstream.h"

 #include "libavcodec/internal.h"

 #include "avformat.h"
 
 #define ADTS_HEADER_SIZE 7
 
 typedef struct {
     int write_adts;
     int objecttype;
     int sample_rate_index;
     int channel_conf;
 } ADTSContext;
 

 static int decode_extradata(AVFormatContext *s, ADTSContext *adts, uint8_t *buf, int size)

 {
     GetBitContext gb;
 
     init_get_bits(&gb, buf, size * 8);
     adts->objecttype = get_bits(&gb, 5) - 1;
     adts->sample_rate_index = get_bits(&gb, 4);
     adts->channel_conf = get_bits(&gb, 4);
 

     if (adts->objecttype > 3) {

         av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);

         return -1;
     }
     if (adts->sample_rate_index == 15) {
         av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
         return -1;
     }
     if (adts->channel_conf == 0) {
         ff_log_missing_feature(s, "PCE based channel configuration", 0);
         return -1;
     }
 

     adts->write_adts = 1;
 
     return 0;
 }
 
 static int adts_write_header(AVFormatContext *s)
 {
     ADTSContext *adts = s->priv_data;
     AVCodecContext *avc = s->streams[0]->codec;
 

     if(avc->extradata_size > 0 &&
             decode_extradata(s, adts, avc->extradata, avc->extradata_size) < 0)
         return -1;

 
     return 0;
 }
 
 static int adts_write_frame_header(AVFormatContext *s, int size)
 {
     ADTSContext *ctx = s->priv_data;
     PutBitContext pb;
     uint8_t buf[ADTS_HEADER_SIZE];
 
     init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
 
     /* adts_fixed_header */
     put_bits(&pb, 12, 0xfff);   /* syncword */
     put_bits(&pb, 1, 0);        /* ID */
     put_bits(&pb, 2, 0);        /* layer */
     put_bits(&pb, 1, 1);        /* protection_absent */
     put_bits(&pb, 2, ctx->objecttype); /* profile_objecttype */
     put_bits(&pb, 4, ctx->sample_rate_index);
     put_bits(&pb, 1, 0);        /* private_bit */
     put_bits(&pb, 3, ctx->channel_conf); /* channel_configuration */
     put_bits(&pb, 1, 0);        /* original_copy */
     put_bits(&pb, 1, 0);        /* home */
 
     /* adts_variable_header */
     put_bits(&pb, 1, 0);        /* copyright_identification_bit */
     put_bits(&pb, 1, 0);        /* copyright_identification_start */
     put_bits(&pb, 13, ADTS_HEADER_SIZE + size); /* aac_frame_length */
     put_bits(&pb, 11, 0x7ff);   /* adts_buffer_fullness */
     put_bits(&pb, 2, 0);        /* number_of_raw_data_blocks_in_frame */
 
     flush_put_bits(&pb);

     put_buffer(s->pb, buf, ADTS_HEADER_SIZE);

 
     return 0;
 }
 
 static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
 {
     ADTSContext *adts = s->priv_data;

     ByteIOContext *pb = s->pb;

     if (!pkt->size)
         return 0;

     if(adts->write_adts)
         adts_write_frame_header(s, pkt->size);
     put_buffer(pb, pkt->data, pkt->size);

     put_flush_packet(pb);

 
     return 0;
 }
 

 AVOutputFormat adts_muxer = {

     "adts",

     NULL_IF_CONFIG_SMALL("ADTS AAC"),

     "audio/aac",
     "aac",
     sizeof(ADTSContext),
     CODEC_ID_AAC,
     CODEC_ID_NONE,
     adts_write_header,
     adts_write_packet,
 };