text: ﻿/*
   * Interplay C93 demuxer
   * Copyright (c) 2007 Anssi Hannula <anssi.hannula@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 "avformat.h"
  #include "internal.h"
  #include "voc.h"
  #include "libavutil/intreadwrite.h"
  
  typedef struct {
      uint16_t index;
      uint8_t length;
      uint8_t frames;
  } C93BlockRecord;
  
  typedef struct {
      VocDecContext voc;
  
      C93BlockRecord block_records[512];
      int current_block;
  
      uint32_t frame_offsets[32];
      int current_frame;
      int next_pkt_is_audio;
  
      AVStream *audio;
  } C93DemuxContext;
  
  static int probe(AVProbeData *p)
  {
      int i;
      int index = 1;
      if (p->buf_size < 16)
          return 0;
      for (i = 0; i < 16; i += 4) {
          if (AV_RL16(p->buf + i) != index || !p->buf[i + 2] || !p->buf[i + 3])
              return 0;
          index += p->buf[i + 2];
      }
      return AVPROBE_SCORE_MAX;
  }
  
  static int read_header(AVFormatContext *s,
                             AVFormatParameters *ap)
  {
      AVStream *video;
      AVIOContext *pb = s->pb;
      C93DemuxContext *c93 = s->priv_data;
      int i;
      int framecount = 0;
  
      for (i = 0; i < 512; i++) {
          c93->block_records[i].index = avio_rl16(pb);
          c93->block_records[i].length = avio_r8(pb);
          c93->block_records[i].frames = avio_r8(pb);
          if (c93->block_records[i].frames > 32) {
              av_log(s, AV_LOG_ERROR, "too many frames in block\n");
              return AVERROR_INVALIDDATA;
          }
          framecount += c93->block_records[i].frames;
      }
  
      /* Audio streams are added if audio packets are found */
      s->ctx_flags |= AVFMTCTX_NOHEADER;
  
      video = avformat_new_stream(s, NULL);
      if (!video)
          return AVERROR(ENOMEM);
  
      video->codec->codec_type = AVMEDIA_TYPE_VIDEO;
      video->codec->codec_id = CODEC_ID_C93;
      video->codec->width = 320;
      video->codec->height = 192;
      /* 4:3 320x200 with 8 empty lines */
      video->sample_aspect_ratio = (AVRational) { 5, 6 };
      avpriv_set_pts_info(video, 64, 2, 25);
      video->nb_frames = framecount;
      video->duration = framecount;
      video->start_time = 0;
  
      c93->current_block = 0;
      c93->current_frame = 0;
      c93->next_pkt_is_audio = 0;
      return 0;
  }
  
  #define C93_HAS_PALETTE 0x01
  #define C93_FIRST_FRAME 0x02
  
  static int read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      AVIOContext *pb = s->pb;
      C93DemuxContext *c93 = s->priv_data;
      C93BlockRecord *br = &c93->block_records[c93->current_block];
      int datasize;
      int ret, i;
  
      if (c93->next_pkt_is_audio) {
          c93->current_frame++;
          c93->next_pkt_is_audio = 0;
          datasize = avio_rl16(pb);
          if (datasize > 42) {
              if (!c93->audio) {
                  c93->audio = avformat_new_stream(s, NULL);
                  if (!c93->audio)
                      return AVERROR(ENOMEM);
                  c93->audio->codec->codec_type = AVMEDIA_TYPE_AUDIO;
              }
              avio_skip(pb, 26); /* VOC header */
              ret = voc_get_packet(s, pkt, c93->audio, datasize - 26);
              if (ret > 0) {
                  pkt->stream_index = 1;
                  pkt->flags |= AV_PKT_FLAG_KEY;
                  return ret;
              }
          }
      }
      if (c93->current_frame >= br->frames) {
          if (c93->current_block >= 511 || !br[1].length)
              return AVERROR(EIO);
          br++;
          c93->current_block++;
          c93->current_frame = 0;
      }
  
      if (c93->current_frame == 0) {
          avio_seek(pb, br->index * 2048, SEEK_SET);
          for (i = 0; i < 32; i++) {
              c93->frame_offsets[i] = avio_rl32(pb);
          }
      }
  
      avio_seek(pb,br->index * 2048 +
              c93->frame_offsets[c93->current_frame], SEEK_SET);
      datasize = avio_rl16(pb); /* video frame size */
  
      ret = av_new_packet(pkt, datasize + 768 + 1);
      if (ret < 0)
          return ret;
      pkt->data[0] = 0;
      pkt->size = datasize + 1;
  
      ret = avio_read(pb, pkt->data + 1, datasize);
      if (ret < datasize) {
          ret = AVERROR(EIO);
          goto fail;
      }
  
      datasize = avio_rl16(pb); /* palette size */
      if (datasize) {
          if (datasize != 768) {
              av_log(s, AV_LOG_ERROR, "invalid palette size %u\n", datasize);
              ret = AVERROR_INVALIDDATA;
              goto fail;
          }
          pkt->data[0] |= C93_HAS_PALETTE;
          ret = avio_read(pb, pkt->data + pkt->size, datasize);
          if (ret < datasize) {
              ret = AVERROR(EIO);
              goto fail;
          }
          pkt->size += 768;
      }
      pkt->stream_index = 0;
      c93->next_pkt_is_audio = 1;
  
      /* only the first frame is guaranteed to not reference previous frames */
      if (c93->current_block == 0 && c93->current_frame == 0) {
          pkt->flags |= AV_PKT_FLAG_KEY;
          pkt->data[0] |= C93_FIRST_FRAME;
      }
      return 0;
  
      fail:
      av_free_packet(pkt);
      return ret;
  }
  
  AVInputFormat ff_c93_demuxer = {
      .name           = "c93",
      .long_name      = NULL_IF_CONFIG_SMALL("Interplay C93"),
      .priv_data_size = sizeof(C93DemuxContext),
      .read_probe     = probe,
      .read_header    = read_header,
      .read_packet    = read_packet,
  };
  