text: /*
   * Psygnosis YOP demuxer
   *
   * Copyright (C) 2010 Mohamed Naufal Basheer <naufal11@gmail.com>
   * derived from the code by
   * Copyright (C) 2009 Thomas P. Higdon <thomas.p.higdon@gmail.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 "libavutil/channel_layout.h"
  #include "libavutil/intreadwrite.h"
  #include "avformat.h"
  #include "internal.h"
  
  typedef struct yop_dec_context {
      AVPacket video_packet;
  
      int odd_frame;
      int frame_size;
      int audio_block_length;
      int palette_size;
  } YopDecContext;
  
  static int yop_probe(AVProbeData *probe_packet)
  {
      if (AV_RB16(probe_packet->buf) == AV_RB16("YO")  &&
          probe_packet->buf[2]<10                      &&
          probe_packet->buf[3]<10                      &&
          probe_packet->buf[6]                         &&
          probe_packet->buf[7]                         &&
          !(probe_packet->buf[8] & 1)                  &&
          !(probe_packet->buf[10] & 1)                 &&
          AV_RL16(probe_packet->buf + 12 + 6) >= 920    &&
          AV_RL16(probe_packet->buf + 12 + 6) < probe_packet->buf[12] * 3 + 4 + probe_packet->buf[7] * 2048
      )
          return AVPROBE_SCORE_MAX * 3 / 4;
  
      return 0;
  }
  
  static int yop_read_header(AVFormatContext *s)
  {
      YopDecContext *yop = s->priv_data;
      AVIOContext *pb  = s->pb;
  
      AVCodecContext *audio_dec, *video_dec;
      AVStream *audio_stream, *video_stream;
  
      int frame_rate, ret;
  
      audio_stream = avformat_new_stream(s, NULL);
      video_stream = avformat_new_stream(s, NULL);
      if (!audio_stream || !video_stream)
          return AVERROR(ENOMEM);
  
      // Extra data that will be passed to the decoder
      video_stream->codec->extradata_size = 8;
  
      video_stream->codec->extradata = av_mallocz(video_stream->codec->extradata_size +
                                                  FF_INPUT_BUFFER_PADDING_SIZE);
  
      if (!video_stream->codec->extradata)
          return AVERROR(ENOMEM);
  
      // Audio
      audio_dec               = audio_stream->codec;
      audio_dec->codec_type   = AVMEDIA_TYPE_AUDIO;
      audio_dec->codec_id     = AV_CODEC_ID_ADPCM_IMA_APC;
      audio_dec->channels     = 1;
      audio_dec->channel_layout = AV_CH_LAYOUT_MONO;
      audio_dec->sample_rate  = 22050;
  
      // Video
      video_dec               = video_stream->codec;
      video_dec->codec_type   = AVMEDIA_TYPE_VIDEO;
      video_dec->codec_id     = AV_CODEC_ID_YOP;
  
      avio_skip(pb, 6);
  
      frame_rate              = avio_r8(pb);
      yop->frame_size         = avio_r8(pb) * 2048;
      video_dec->width        = avio_rl16(pb);
      video_dec->height       = avio_rl16(pb);
  
      video_stream->sample_aspect_ratio = (AVRational){1, 2};
  
      ret = avio_read(pb, video_dec->extradata, 8);
      if (ret < 8)
          return ret < 0 ? ret : AVERROR_EOF;
  
      yop->palette_size       = video_dec->extradata[0] * 3 + 4;
      yop->audio_block_length = AV_RL16(video_dec->extradata + 6);
  
      video_dec->bit_rate     = 8 * (yop->frame_size - yop->audio_block_length) * frame_rate;
  
      // 1840 samples per frame, 1 nibble per sample; hence 1840/2 = 920
      if (yop->audio_block_length < 920 ||
          yop->audio_block_length + yop->palette_size >= yop->frame_size) {
          av_log(s, AV_LOG_ERROR, "YOP has invalid header\n");
          return AVERROR_INVALIDDATA;
      }
  
      avio_seek(pb, 2048, SEEK_SET);
  
      avpriv_set_pts_info(video_stream, 32, 1, frame_rate);
  
      return 0;
  }
  
  static int yop_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      YopDecContext *yop = s->priv_data;
      AVIOContext *pb  = s->pb;
  
      int ret;
      int actual_video_data_size = yop->frame_size -
                                   yop->audio_block_length - yop->palette_size;
  
      yop->video_packet.stream_index = 1;
  
      if (yop->video_packet.data) {
          *pkt                   =  yop->video_packet;
          yop->video_packet.data =  NULL;
          yop->video_packet.size =  0;
          pkt->data[0]           =  yop->odd_frame;
          pkt->flags             |= AV_PKT_FLAG_KEY;
          yop->odd_frame         ^= 1;
          return pkt->size;
      }
      ret = av_new_packet(&yop->video_packet,
                          yop->frame_size - yop->audio_block_length);
      if (ret < 0)
          return ret;
  
      yop->video_packet.pos = avio_tell(pb);
  
      ret = avio_read(pb, yop->video_packet.data, yop->palette_size);
      if (ret < 0) {
          goto err_out;
      }else if (ret < yop->palette_size) {
          ret = AVERROR_EOF;
          goto err_out;
      }
  
      ret = av_get_packet(pb, pkt, 920);
      if (ret < 0)
          goto err_out;
  
      // Set position to the start of the frame
      pkt->pos = yop->video_packet.pos;
  
      avio_skip(pb, yop->audio_block_length - ret);
  
      ret = avio_read(pb, yop->video_packet.data + yop->palette_size,
                       actual_video_data_size);
      if (ret < 0)
          goto err_out;
      else if (ret < actual_video_data_size)
          av_shrink_packet(&yop->video_packet, yop->palette_size + ret);
  
      // Arbitrarily return the audio data first
      return yop->audio_block_length;
  
  err_out:
      av_free_packet(&yop->video_packet);
      return ret;
  }
  
  static int yop_read_close(AVFormatContext *s)
  {
      YopDecContext *yop = s->priv_data;
      av_free_packet(&yop->video_packet);
      return 0;
  }
  
  static int yop_read_seek(AVFormatContext *s, int stream_index,
                           int64_t timestamp, int flags)
  {
      YopDecContext *yop = s->priv_data;
      int64_t frame_pos, pos_min, pos_max;
      int frame_count;
  
      if (!stream_index)
          return -1;
  
      pos_min        = s->data_offset;
      pos_max        = avio_size(s->pb) - yop->frame_size;
      frame_count    = (pos_max - pos_min) / yop->frame_size;
  
      timestamp      = FFMAX(0, FFMIN(frame_count, timestamp));
  
      frame_pos      = timestamp * yop->frame_size + pos_min;
  
      if (avio_seek(s->pb, frame_pos, SEEK_SET) < 0)
          return -1;
  
      av_free_packet(&yop->video_packet);
      yop->odd_frame = timestamp & 1;
  
      return 0;
  }
  
  AVInputFormat ff_yop_demuxer = {
      .name           = "yop",
      .long_name      = NULL_IF_CONFIG_SMALL("Psygnosis YOP"),
      .priv_data_size = sizeof(YopDecContext),
      .read_probe     = yop_probe,
      .read_header    = yop_read_header,
      .read_packet    = yop_read_packet,
      .read_close     = yop_read_close,
      .read_seek      = yop_read_seek,
      .extensions     = "yop",
      .flags          = AVFMT_GENERIC_INDEX,
  };
  