text: /*
   * 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/get_bits.h"
  #include "libavcodec/put_bits.h"
  #include "libavcodec/avcodec.h"
  #include "libavcodec/mpeg4audio.h"
  #include "libavutil/opt.h"
  #include "avformat.h"
  #include "apetag.h"
  #include "id3v2.h"
  
  #define ADTS_HEADER_SIZE 7
  
  typedef struct ADTSContext {
      AVClass *class;
      int write_adts;
      int objecttype;
      int sample_rate_index;
      int channel_conf;
      int pce_size;
      int apetag;
      int id3v2tag;
      int mpeg_id;
      uint8_t pce_data[MAX_PCE_SIZE];
  } ADTSContext;
  
  #define ADTS_MAX_FRAME_BYTES ((1 << 13) - 1)
  
  static int adts_decode_extradata(AVFormatContext *s, ADTSContext *adts, const uint8_t *buf, int size)
  {
      GetBitContext gb;
      PutBitContext pb;
      MPEG4AudioConfig m4ac;
      int off;
  
      init_get_bits(&gb, buf, size * 8);
      off = avpriv_mpeg4audio_get_config2(&m4ac, buf, size, 1, s);
      if (off < 0)
          return off;
      skip_bits_long(&gb, off);
      adts->objecttype        = m4ac.object_type - 1;
      adts->sample_rate_index = m4ac.sampling_index;
      adts->channel_conf      = m4ac.chan_config;
  
      if (adts->objecttype > 3U) {
          av_log(s, AV_LOG_ERROR, "MPEG-4 AOT %d is not allowed in ADTS\n", adts->objecttype+1);
          return AVERROR_INVALIDDATA;
      }
      if (adts->sample_rate_index == 15) {
          av_log(s, AV_LOG_ERROR, "Escape sample rate index illegal in ADTS\n");
          return AVERROR_INVALIDDATA;
      }
      if (get_bits(&gb, 1)) {
          av_log(s, AV_LOG_ERROR, "960/120 MDCT window is not allowed in ADTS\n");
          return AVERROR_INVALIDDATA;
      }
      if (get_bits(&gb, 1)) {
          av_log(s, AV_LOG_ERROR, "Scalable configurations are not allowed in ADTS\n");
          return AVERROR_INVALIDDATA;
      }
      if (get_bits(&gb, 1)) {
          av_log(s, AV_LOG_ERROR, "Extension flag is not allowed in ADTS\n");
          return AVERROR_INVALIDDATA;
      }
      if (!adts->channel_conf) {
          init_put_bits(&pb, adts->pce_data, MAX_PCE_SIZE);
  
          put_bits(&pb, 3, 5); //ID_PCE
          adts->pce_size = (ff_copy_pce_data(&pb, &gb) + 3) / 8;
          flush_put_bits(&pb);
      }
  
      adts->write_adts = 1;
  
      return 0;
  }
  
  static int adts_init(AVFormatContext *s)
  {
      ADTSContext *adts = s->priv_data;
      AVCodecParameters *par = s->streams[0]->codecpar;
  
      if (par->codec_id != AV_CODEC_ID_AAC) {
          av_log(s, AV_LOG_ERROR, "Only AAC streams can be muxed by the ADTS muxer\n");
          return AVERROR(EINVAL);
      }
      if (par->extradata_size > 0)
          return adts_decode_extradata(s, adts, par->extradata,
                                       par->extradata_size);
  
      return 0;
  }
  
  static int adts_write_header(AVFormatContext *s)
  {
      ADTSContext *adts = s->priv_data;
  
      if (adts->id3v2tag)
          ff_id3v2_write_simple(s, 4, ID3v2_DEFAULT_MAGIC);
  
      return 0;
  }
  
  static int adts_write_frame_header(ADTSContext *ctx,
                                     uint8_t *buf, int size, int pce_size)
  {
      PutBitContext pb;
  
      unsigned full_frame_size = (unsigned)ADTS_HEADER_SIZE + size + pce_size;
      if (full_frame_size > ADTS_MAX_FRAME_BYTES) {
          av_log(NULL, AV_LOG_ERROR, "ADTS frame size too large: %u (max %d)\n",
                 full_frame_size, ADTS_MAX_FRAME_BYTES);
          return AVERROR_INVALIDDATA;
      }
  
      init_put_bits(&pb, buf, ADTS_HEADER_SIZE);
  
      /* adts_fixed_header */
      put_bits(&pb, 12, 0xfff);   /* syncword */
      put_bits(&pb, 1, ctx->mpeg_id); /* 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, full_frame_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);
  
      return 0;
  }
  
  static int adts_write_packet(AVFormatContext *s, AVPacket *pkt)
  {
      ADTSContext *adts = s->priv_data;
      AVCodecParameters *par = s->streams[0]->codecpar;
      AVIOContext *pb = s->pb;
      uint8_t buf[ADTS_HEADER_SIZE];
  
      if (!pkt->size)
          return 0;
      if (!par->extradata_size) {
          uint8_t *side_data;
          int side_data_size, ret;
  
          side_data = av_packet_get_side_data(pkt, AV_PKT_DATA_NEW_EXTRADATA,
                                              &side_data_size);
          if (side_data_size) {
              ret = adts_decode_extradata(s, adts, side_data, side_data_size);
              if (ret < 0)
                  return ret;
              ret = ff_alloc_extradata(par, side_data_size);
              if (ret < 0)
                  return ret;
              memcpy(par->extradata, side_data, side_data_size);
          }
      }
      if (adts->write_adts) {
          int err = adts_write_frame_header(adts, buf, pkt->size,
                                               adts->pce_size);
          if (err < 0)
              return err;
          avio_write(pb, buf, ADTS_HEADER_SIZE);
          if (adts->pce_size) {
              avio_write(pb, adts->pce_data, adts->pce_size);
              adts->pce_size = 0;
          }
      }
      avio_write(pb, pkt->data, pkt->size);
  
      return 0;
  }
  
  static int adts_write_trailer(AVFormatContext *s)
  {
      ADTSContext *adts = s->priv_data;
  
      if (adts->apetag)
          ff_ape_write_tag(s);
  
      return 0;
  }
  
  #define ENC AV_OPT_FLAG_ENCODING_PARAM
  #define OFFSET(obj) offsetof(ADTSContext, obj)
  static const AVOption options[] = {
      { "write_id3v2",  "Enable ID3v2 tag writing", OFFSET(id3v2tag), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, ENC},
      { "write_apetag", "Enable APE tag writing",   OFFSET(apetag),   AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, ENC},
      { "write_mpeg2",  "Use MPE2 ID when writing", OFFSET(mpeg_id),  AV_OPT_TYPE_BOOL,  {.i64 = 0}, 0, 1, ENC, "mpeg_id"},
      { NULL },
  };
  
  static const AVClass adts_muxer_class = {
      .class_name     = "ADTS muxer",
      .item_name      = av_default_item_name,
      .option         = options,
      .version        = LIBAVUTIL_VERSION_INT,
  };
  
  AVOutputFormat ff_adts_muxer = {
      .name              = "adts",
      .long_name         = NULL_IF_CONFIG_SMALL("ADTS AAC (Advanced Audio Coding)"),
      .mime_type         = "audio/aac",
      .extensions        = "aac,adts",
      .priv_data_size    = sizeof(ADTSContext),
      .audio_codec       = AV_CODEC_ID_AAC,
      .video_codec       = AV_CODEC_ID_NONE,
      .init              = adts_init,
      .write_header      = adts_write_header,
      .write_packet      = adts_write_packet,
      .write_trailer     = adts_write_trailer,
      .priv_class        = &adts_muxer_class,
      .flags             = AVFMT_NOTIMESTAMPS,
  };
  