text: /*
   * amr file format
   * Copyright (c) 2001 FFmpeg project
   *
   * This file is part of Libav.
   *
   * Libav 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.
   *
   * Libav 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 Libav; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  /*
  Write and read amr data according to RFC3267, http://www.ietf.org/rfc/rfc3267.txt?number=3267
  
  Only mono files are supported.
  
  */
  
  #include "libavutil/channel_layout.h"
  #include "avformat.h"
  #include "internal.h"
  
  static const char AMR_header[]   = "#!AMR\n";
  static const char AMRWB_header[] = "#!AMR-WB\n";
  
  #if CONFIG_AMR_MUXER
  static int amr_write_header(AVFormatContext *s)
  {
      AVIOContext    *pb  = s->pb;
      AVCodecParameters *par = s->streams[0]->codecpar;
  
      s->priv_data = NULL;
  
      if (par->codec_id == AV_CODEC_ID_AMR_NB) {
          avio_write(pb, AMR_header,   sizeof(AMR_header)   - 1); /* magic number */
      } else if (par->codec_id == AV_CODEC_ID_AMR_WB) {
          avio_write(pb, AMRWB_header, sizeof(AMRWB_header) - 1); /* magic number */
      } else {
          return -1;
      }
      avio_flush(pb);
      return 0;
  }
  
  static int amr_write_packet(AVFormatContext *s, AVPacket *pkt)
  {
      avio_write(s->pb, pkt->data, pkt->size);
      return 0;
  }
  #endif /* CONFIG_AMR_MUXER */
  
  static int amr_probe(AVProbeData *p)
  {
      // Only check for "#!AMR" which could be amr-wb, amr-nb.
      // This will also trigger multichannel files: "#!AMR_MC1.0\n" and
      // "#!AMR-WB_MC1.0\n" (not supported)
  
      if (!memcmp(p->buf, AMR_header, 5))
          return AVPROBE_SCORE_MAX;
      else
          return 0;
  }
  
  /* amr input */
  static int amr_read_header(AVFormatContext *s)
  {
      AVIOContext *pb = s->pb;
      AVStream *st;
      uint8_t header[9];
  
      avio_read(pb, header, 6);
  
      st = avformat_new_stream(s, NULL);
      if (!st)
          return AVERROR(ENOMEM);
      if (memcmp(header, AMR_header, 6)) {
          avio_read(pb, header + 6, 3);
          if (memcmp(header, AMRWB_header, 9)) {
              return -1;
          }
  
          st->codecpar->codec_tag   = MKTAG('s', 'a', 'w', 'b');
          st->codecpar->codec_id    = AV_CODEC_ID_AMR_WB;
          st->codecpar->sample_rate = 16000;
      } else {
          st->codecpar->codec_tag   = MKTAG('s', 'a', 'm', 'r');
          st->codecpar->codec_id    = AV_CODEC_ID_AMR_NB;
          st->codecpar->sample_rate = 8000;
      }
      st->codecpar->channels   = 1;
      st->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
      st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
      avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
  
      return 0;
  }
  
  static int amr_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      AVCodecParameters *par = s->streams[0]->codecpar;
      int read, size = 0, toc, mode;
      int64_t pos = avio_tell(s->pb);
  
      if (s->pb->eof_reached) {
          return AVERROR(EIO);
      }
  
      // FIXME this is wrong, this should rather be in an AVParser
      toc  = avio_r8(s->pb);
      mode = (toc >> 3) & 0x0F;
  
      if (par->codec_id == AV_CODEC_ID_AMR_NB) {
          static const uint8_t packed_size[16] = {
              12, 13, 15, 17, 19, 20, 26, 31, 5, 0, 0, 0, 0, 0, 0, 0
          };
  
          size = packed_size[mode] + 1;
      } else if (par->codec_id == AV_CODEC_ID_AMR_WB) {
          static const uint8_t packed_size[16] = {
              18, 24, 33, 37, 41, 47, 51, 59, 61, 6, 6, 0, 0, 0, 1, 1
          };
  
          size = packed_size[mode];
      } else {
          assert(0);
      }
  
      if (!size || av_new_packet(pkt, size))
          return AVERROR(EIO);
  
      /* Both AMR formats have 50 frames per second */
      s->streams[0]->codecpar->bit_rate = size*8*50;
  
      pkt->stream_index = 0;
      pkt->pos          = pos;
      pkt->data[0]      = toc;
      pkt->duration     = par->codec_id == AV_CODEC_ID_AMR_NB ? 160 : 320;
      read              = avio_read(s->pb, pkt->data + 1, size - 1);
  
      if (read != size - 1) {
          av_packet_unref(pkt);
          return AVERROR(EIO);
      }
  
      return 0;
  }
  
  #if CONFIG_AMR_DEMUXER
  AVInputFormat ff_amr_demuxer = {
      .name           = "amr",
      .long_name      = NULL_IF_CONFIG_SMALL("3GPP AMR"),
      .read_probe     = amr_probe,
      .read_header    = amr_read_header,
      .read_packet    = amr_read_packet,
      .flags          = AVFMT_GENERIC_INDEX,
  };
  #endif
  
  #if CONFIG_AMR_MUXER
  AVOutputFormat ff_amr_muxer = {
      .name              = "amr",
      .long_name         = NULL_IF_CONFIG_SMALL("3GPP AMR"),
      .mime_type         = "audio/amr",
      .extensions        = "amr",
      .audio_codec       = AV_CODEC_ID_AMR_NB,
      .video_codec       = AV_CODEC_ID_NONE,
      .write_header      = amr_write_header,
      .write_packet      = amr_write_packet,
      .flags             = AVFMT_NOTIMESTAMPS,
  };
  #endif
  