text: /*
   * MatchWare Screen Capture Codec decoder
   *
   * Copyright (c) 2018 Paul B Mahol
   *
   * 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 <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "avcodec.h"
  #include "bytestream.h"
  #include "internal.h"
  
  #include <zlib.h>
  
  typedef struct MWSCContext {
      unsigned int      decomp_size;
      uint8_t          *decomp_buf;
      z_stream          zstream;
      AVFrame          *prev_frame;
  } MWSCContext;
  
  static int rle_uncompress(GetByteContext *gb, PutByteContext *pb, GetByteContext *gbp,
                            int width, int height, int stride, int pb_linesize, int gbp_linesize)
  {
      int intra = 1, w = 0;
  
      bytestream2_seek_p(pb, (height - 1) * pb_linesize, SEEK_SET);
  
      while (bytestream2_get_bytes_left(gb) > 0) {
          uint32_t fill = bytestream2_get_le24(gb);
          unsigned run = bytestream2_get_byte(gb);
  
          if (run == 0) {
              run = bytestream2_get_le32(gb);
              for (int j = 0; j < run; j++, w++) {
                  if (w == width) {
                      w = 0;
                      bytestream2_seek_p(pb, -(pb_linesize + stride), SEEK_CUR);
                  }
                  bytestream2_put_le24(pb, fill);
              }
          } else if (run == 255) {
              int pos = bytestream2_tell_p(pb);
  
              bytestream2_seek(gbp, pos, SEEK_SET);
              for (int j = 0; j < fill; j++, w++) {
                  if (w == width) {
                      w = 0;
                      bytestream2_seek_p(pb, -(pb_linesize + stride), SEEK_CUR);
                      bytestream2_seek(gbp, -(gbp_linesize + stride), SEEK_CUR);
                  }
                  bytestream2_put_le24(pb, bytestream2_get_le24(gbp));
              }
  
              intra = 0;
          } else {
              for (int j = 0; j < run; j++, w++) {
                  if (w == width) {
                      w = 0;
                      bytestream2_seek_p(pb, -(pb_linesize + stride), SEEK_CUR);
                  }
                  bytestream2_put_le24(pb, fill);
              }
          }
      }
  
      return intra;
  }
  
  static int decode_frame(AVCodecContext *avctx,
                          void *data, int *got_frame,
                          AVPacket *avpkt)
  {
      MWSCContext *s = avctx->priv_data;
      AVFrame *frame = data;
      uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      GetByteContext gb;
      GetByteContext gbp;
      PutByteContext pb;
      int ret;
  
      ret = inflateReset(&s->zstream);
      if (ret != Z_OK) {
          av_log(avctx, AV_LOG_ERROR, "Inflate reset error: %d\n", ret);
          return AVERROR_EXTERNAL;
      }
      s->zstream.next_in   = buf;
      s->zstream.avail_in  = buf_size;
      s->zstream.next_out  = s->decomp_buf;
      s->zstream.avail_out = s->decomp_size;
      ret = inflate(&s->zstream, Z_FINISH);
      if (ret != Z_STREAM_END) {
          av_log(avctx, AV_LOG_ERROR, "Inflate error: %d\n", ret);
          return AVERROR_EXTERNAL;
      }
  
      if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
          return ret;
  
      bytestream2_init(&gb, s->decomp_buf, s->zstream.total_out);
      bytestream2_init(&gbp, s->prev_frame->data[0], avctx->height * s->prev_frame->linesize[0]);
      bytestream2_init_writer(&pb, frame->data[0], avctx->height * frame->linesize[0]);
  
      frame->key_frame = rle_uncompress(&gb, &pb, &gbp, avctx->width, avctx->height, avctx->width * 3,
                                        frame->linesize[0], s->prev_frame->linesize[0]);
  
      frame->pict_type = frame->key_frame ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
  
      av_frame_unref(s->prev_frame);
      if ((ret = av_frame_ref(s->prev_frame, frame)) < 0)
          return ret;
  
      *got_frame = 1;
  
      return avpkt->size;
  }
  
  static av_cold int decode_init(AVCodecContext *avctx)
  {
      MWSCContext *s = avctx->priv_data;
      int64_t size;
      int zret;
  
      avctx->pix_fmt = AV_PIX_FMT_BGR24;
  
      size = 32LL * avctx->height * avctx->width;
      if (size >= INT32_MAX)
          return AVERROR_INVALIDDATA;
      s->decomp_size = size;
      if (!(s->decomp_buf = av_malloc(s->decomp_size)))
          return AVERROR(ENOMEM);
  
      s->zstream.zalloc = Z_NULL;
      s->zstream.zfree = Z_NULL;
      s->zstream.opaque = Z_NULL;
      zret = inflateInit(&s->zstream);
      if (zret != Z_OK) {
          av_log(avctx, AV_LOG_ERROR, "Inflate init error: %d\n", zret);
          return AVERROR_EXTERNAL;
      }
  
      s->prev_frame = av_frame_alloc();
      if (!s->prev_frame)
          return AVERROR(ENOMEM);
  
      return 0;
  }
  
  static av_cold int decode_close(AVCodecContext *avctx)
  {
      MWSCContext *s = avctx->priv_data;
  
      av_frame_free(&s->prev_frame);
      av_freep(&s->decomp_buf);
      s->decomp_size = 0;
      inflateEnd(&s->zstream);
  
      return 0;
  }
  
  AVCodec ff_mwsc_decoder = {
      .name             = "mwsc",
      .long_name        = NULL_IF_CONFIG_SMALL("MatchWare Screen Capture Codec"),
      .type             = AVMEDIA_TYPE_VIDEO,
      .id               = AV_CODEC_ID_MWSC,
      .priv_data_size   = sizeof(MWSCContext),
      .init             = decode_init,
      .close            = decode_close,
      .decode           = decode_frame,
      .capabilities     = AV_CODEC_CAP_DR1,
      .caps_internal    = FF_CODEC_CAP_INIT_THREADSAFE |
                          FF_CODEC_CAP_INIT_CLEANUP,
  };
  