text: /*
   * 8088flex TMV file demuxer
   * Copyright (c) 2009 Daniel Verkamp <daniel at drv.nu>
   *
   * 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
   */
  
  /**
   * @file
   * 8088flex TMV file demuxer
   * @author Daniel Verkamp
   * @see http://www.oldskool.org/pc/8088_Corruption
   */
  
  #include "libavutil/channel_layout.h"
  #include "libavutil/intreadwrite.h"
  #include "avformat.h"
  #include "internal.h"
  
  enum {
      TMV_PADDING = 0x01,
      TMV_STEREO  = 0x02,
  };
  
  #define TMV_TAG MKTAG('T', 'M', 'A', 'V')
  
  typedef struct TMVContext {
      unsigned audio_chunk_size;
      unsigned video_chunk_size;
      unsigned padding;
      unsigned stream_index;
  } TMVContext;
  
  #define TMV_HEADER_SIZE       12
  
  #define PROBE_MIN_SAMPLE_RATE 5000
  #define PROBE_MAX_FPS         120
  #define PROBE_MIN_AUDIO_SIZE  (PROBE_MIN_SAMPLE_RATE / PROBE_MAX_FPS)
  
  static int tmv_probe(const AVProbeData *p)
  {
      if (AV_RL32(p->buf)   == TMV_TAG &&
          AV_RL16(p->buf+4) >= PROBE_MIN_SAMPLE_RATE &&
          AV_RL16(p->buf+6) >= PROBE_MIN_AUDIO_SIZE  &&
                 !p->buf[8] && // compression method
                  p->buf[9] && // char cols
                  p->buf[10])  // char rows
          return AVPROBE_SCORE_MAX /
              ((p->buf[9] == 40 && p->buf[10] == 25) ? 1 : 4);
      return 0;
  }
  
  static int tmv_read_header(AVFormatContext *s)
  {
      TMVContext *tmv   = s->priv_data;
      AVIOContext *pb = s->pb;
      AVStream *vst, *ast;
      AVRational fps;
      unsigned comp_method, char_cols, char_rows, features;
  
      if (avio_rl32(pb) != TMV_TAG)
          return -1;
  
      if (!(vst = avformat_new_stream(s, NULL)))
          return AVERROR(ENOMEM);
  
      if (!(ast = avformat_new_stream(s, NULL)))
          return AVERROR(ENOMEM);
  
      ast->codecpar->sample_rate = avio_rl16(pb);
      if (!ast->codecpar->sample_rate) {
          av_log(s, AV_LOG_ERROR, "invalid sample rate\n");
          return -1;
      }
  
      tmv->audio_chunk_size   = avio_rl16(pb);
      if (!tmv->audio_chunk_size) {
          av_log(s, AV_LOG_ERROR, "invalid audio chunk size\n");
          return -1;
      }
  
      comp_method             = avio_r8(pb);
      if (comp_method) {
          av_log(s, AV_LOG_ERROR, "unsupported compression method %d\n",
                 comp_method);
          return -1;
      }
  
      char_cols = avio_r8(pb);
      char_rows = avio_r8(pb);
      tmv->video_chunk_size = char_cols * char_rows * 2;
  
      features  = avio_r8(pb);
      if (features & ~(TMV_PADDING | TMV_STEREO)) {
          av_log(s, AV_LOG_ERROR, "unsupported features 0x%02x\n",
                 features & ~(TMV_PADDING | TMV_STEREO));
          return -1;
      }
  
      ast->codecpar->codec_type            = AVMEDIA_TYPE_AUDIO;
      ast->codecpar->codec_id              = AV_CODEC_ID_PCM_U8;
      if (features & TMV_STEREO) {
          ast->codecpar->channels       = 2;
          ast->codecpar->channel_layout = AV_CH_LAYOUT_STEREO;
      } else {
          ast->codecpar->channels       = 1;
          ast->codecpar->channel_layout = AV_CH_LAYOUT_MONO;
      }
      ast->codecpar->bits_per_coded_sample = 8;
      ast->codecpar->bit_rate              = ast->codecpar->sample_rate *
                                             ast->codecpar->bits_per_coded_sample;
      avpriv_set_pts_info(ast, 32, 1, ast->codecpar->sample_rate);
  
      fps.num = ast->codecpar->sample_rate * ast->codecpar->channels;
      fps.den = tmv->audio_chunk_size;
      av_reduce(&fps.num, &fps.den, fps.num, fps.den, 0xFFFFFFFFLL);
  
      vst->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
      vst->codecpar->codec_id   = AV_CODEC_ID_TMV;
      vst->codecpar->format     = AV_PIX_FMT_PAL8;
      vst->codecpar->width      = char_cols * 8;
      vst->codecpar->height     = char_rows * 8;
      avpriv_set_pts_info(vst, 32, fps.den, fps.num);
  
      if (features & TMV_PADDING)
          tmv->padding =
              ((tmv->video_chunk_size + tmv->audio_chunk_size + 511) & ~511) -
               (tmv->video_chunk_size + tmv->audio_chunk_size);
  
      vst->codecpar->bit_rate = ((tmv->video_chunk_size + tmv->padding) *
                                 fps.num * 8) / fps.den;
  
      return 0;
  }
  
  static int tmv_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      TMVContext *tmv   = s->priv_data;
      AVIOContext *pb = s->pb;
      int ret, pkt_size = tmv->stream_index ?
                          tmv->audio_chunk_size : tmv->video_chunk_size;
  
      if (avio_feof(pb))
          return AVERROR_EOF;
  
      ret = av_get_packet(pb, pkt, pkt_size);
  
      if (tmv->stream_index)
          avio_skip(pb, tmv->padding);
  
      pkt->stream_index  = tmv->stream_index;
      tmv->stream_index ^= 1;
      pkt->flags        |= AV_PKT_FLAG_KEY;
  
      return ret;
  }
  
  static int tmv_read_seek(AVFormatContext *s, int stream_index,
                           int64_t timestamp, int flags)
  {
      TMVContext *tmv = s->priv_data;
      int64_t pos;
  
      if (stream_index)
          return -1;
  
      pos = timestamp *
            (tmv->audio_chunk_size + tmv->video_chunk_size + tmv->padding);
  
      if (avio_seek(s->pb, pos + TMV_HEADER_SIZE, SEEK_SET) < 0)
          return -1;
      tmv->stream_index = 0;
      return 0;
  }
  
  AVInputFormat ff_tmv_demuxer = {
      .name           = "tmv",
      .long_name      = NULL_IF_CONFIG_SMALL("8088flex TMV"),
      .priv_data_size = sizeof(TMVContext),
      .read_probe     = tmv_probe,
      .read_header    = tmv_read_header,
      .read_packet    = tmv_read_packet,
      .read_seek      = tmv_read_seek,
      .flags          = AVFMT_GENERIC_INDEX,
  };
  