text: /*
   * Electronic Arts CMV Video Decoder
   * Copyright (c) 2007-2008 Peter Ross
   *
   * 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 St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  
  /**
   * @file
   * Electronic Arts CMV Video Decoder
   * by Peter Ross (pross@xvid.org)
   *
   * Technical details here:
   * http://wiki.multimedia.cx/index.php?title=Electronic_Arts_CMV
   */
  
  #include "libavutil/common.h"
  #include "libavutil/intreadwrite.h"
  #include "libavutil/imgutils.h"
  #include "avcodec.h"
  #include "internal.h"
  
  typedef struct CmvContext {
      AVCodecContext *avctx;
      AVFrame *last_frame;   ///< last
      AVFrame *last2_frame;  ///< second-last
      int width, height;
      unsigned int palette[AVPALETTE_COUNT];
  } CmvContext;
  
  static av_cold int cmv_decode_init(AVCodecContext *avctx){
      CmvContext *s = avctx->priv_data;
  
      s->avctx = avctx;
      avctx->pix_fmt = AV_PIX_FMT_PAL8;
  
      s->last_frame  = av_frame_alloc();
      s->last2_frame = av_frame_alloc();
      if (!s->last_frame || !s->last2_frame) {
          av_frame_free(&s->last_frame);
          av_frame_free(&s->last2_frame);
          return AVERROR(ENOMEM);
      }
  
      return 0;
  }
  
  static void cmv_decode_intra(CmvContext * s, AVFrame *frame,
                               const uint8_t *buf, const uint8_t *buf_end)
  {
      unsigned char *dst = frame->data[0];
      int i;
  
      for (i=0; i < s->avctx->height && buf_end - buf >= s->avctx->width; i++) {
          memcpy(dst, buf, s->avctx->width);
          dst += frame->linesize[0];
          buf += s->avctx->width;
      }
  }
  
  static void cmv_motcomp(unsigned char *dst, ptrdiff_t dst_stride,
                          const unsigned char *src, ptrdiff_t src_stride,
                          int x, int y,
                          int xoffset, int yoffset,
                          int width, int height){
      int i,j;
  
      for(j=y;j<y+4;j++)
      for(i=x;i<x+4;i++)
      {
          if (i+xoffset>=0 && i+xoffset<width &&
              j+yoffset>=0 && j+yoffset<height) {
              dst[j*dst_stride + i] = src[(j+yoffset)*src_stride + i+xoffset];
          }else{
              dst[j*dst_stride + i] = 0;
          }
      }
  }
  
  static void cmv_decode_inter(CmvContext *s, AVFrame *frame, const uint8_t *buf,
                               const uint8_t *buf_end)
  {
      const uint8_t *raw = buf + (s->avctx->width*s->avctx->height/16);
      int x,y,i;
  
      i = 0;
      for(y=0; y<s->avctx->height/4; y++)
      for(x=0; x<s->avctx->width/4 && buf_end - buf > i; x++) {
          if (buf[i]==0xFF) {
              unsigned char *dst = frame->data[0] + (y*4)*frame->linesize[0] + x*4;
              if (raw+16<buf_end && *raw==0xFF) { /* intra */
                  raw++;
                  memcpy(dst, raw, 4);
                  memcpy(dst +     frame->linesize[0], raw+4, 4);
                  memcpy(dst + 2 * frame->linesize[0], raw+8, 4);
                  memcpy(dst + 3 * frame->linesize[0], raw+12, 4);
                  raw+=16;
              }else if(raw<buf_end) {  /* inter using second-last frame as reference */
                  int xoffset = (*raw & 0xF) - 7;
                  int yoffset = ((*raw >> 4)) - 7;
                  if (s->last2_frame->data[0])
                      cmv_motcomp(frame->data[0], frame->linesize[0],
                                  s->last2_frame->data[0], s->last2_frame->linesize[0],
                                  x*4, y*4, xoffset, yoffset, s->avctx->width, s->avctx->height);
                  raw++;
              }
          }else{  /* inter using last frame as reference */
              int xoffset = (buf[i] & 0xF) - 7;
              int yoffset = ((buf[i] >> 4)) - 7;
              if (s->last_frame->data[0])
                  cmv_motcomp(frame->data[0], frame->linesize[0],
                              s->last_frame->data[0], s->last_frame->linesize[0],
                              x*4, y*4, xoffset, yoffset, s->avctx->width, s->avctx->height);
          }
          i++;
      }
  }
  
  static int cmv_process_header(CmvContext *s, const uint8_t *buf, const uint8_t *buf_end)
  {
      int pal_start, pal_count, i, ret, fps;
  
      if(buf_end - buf < 16) {
          av_log(s->avctx, AV_LOG_WARNING, "truncated header\n");
          return AVERROR_INVALIDDATA;
      }
  
      s->width  = AV_RL16(&buf[4]);
      s->height = AV_RL16(&buf[6]);
  
      if (s->width  != s->avctx->width ||
          s->height != s->avctx->height) {
          av_frame_unref(s->last_frame);
          av_frame_unref(s->last2_frame);
      }
  
      ret = ff_set_dimensions(s->avctx, s->width, s->height);
      if (ret < 0)
          return ret;
  
      fps = AV_RL16(&buf[10]);
      if (fps > 0)
          s->avctx->framerate = (AVRational){ fps, 1 };
  
      pal_start = AV_RL16(&buf[12]);
      pal_count = AV_RL16(&buf[14]);
  
      buf += 16;
      for (i=pal_start; i<pal_start+pal_count && i<AVPALETTE_COUNT && buf_end - buf >= 3; i++) {
          s->palette[i] = 0xFFU << 24 | AV_RB24(buf);
          buf += 3;
      }
  
      return 0;
  }
  
  #define EA_PREAMBLE_SIZE 8
  #define MVIh_TAG MKTAG('M', 'V', 'I', 'h')
  
  static int cmv_decode_frame(AVCodecContext *avctx,
                              void *data, int *got_frame,
                              AVPacket *avpkt)
  {
      const uint8_t *buf = avpkt->data;
      int buf_size = avpkt->size;
      CmvContext *s = avctx->priv_data;
      const uint8_t *buf_end = buf + buf_size;
      AVFrame *frame = data;
      int ret;
  
      if (buf_end - buf < EA_PREAMBLE_SIZE)
          return AVERROR_INVALIDDATA;
  
      if (AV_RL32(buf)==MVIh_TAG||AV_RB32(buf)==MVIh_TAG) {
          unsigned size = AV_RL32(buf + 4);
          ret = cmv_process_header(s, buf+EA_PREAMBLE_SIZE, buf_end);
          if (ret < 0)
              return ret;
          if (size > buf_end - buf - EA_PREAMBLE_SIZE)
              return AVERROR_INVALIDDATA;
          buf += size;
      }
  
      if ((ret = av_image_check_size(s->width, s->height, 0, s->avctx)) < 0)
          return ret;
  
      if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
          return ret;
  
      memcpy(frame->data[1], s->palette, AVPALETTE_SIZE);
  
      buf += EA_PREAMBLE_SIZE;
      if ((buf[0]&1)) {  // subtype
          cmv_decode_inter(s, frame, buf+2, buf_end);
          frame->key_frame = 0;
          frame->pict_type = AV_PICTURE_TYPE_P;
      }else{
          frame->key_frame = 1;
          frame->pict_type = AV_PICTURE_TYPE_I;
          cmv_decode_intra(s, frame, buf+2, buf_end);
      }
  
      av_frame_unref(s->last2_frame);
      av_frame_move_ref(s->last2_frame, s->last_frame);
      if ((ret = av_frame_ref(s->last_frame, frame)) < 0)
          return ret;
  
      *got_frame = 1;
  
      return buf_size;
  }
  
  static av_cold int cmv_decode_end(AVCodecContext *avctx){
      CmvContext *s = avctx->priv_data;
  
      av_frame_free(&s->last_frame);
      av_frame_free(&s->last2_frame);
  
      return 0;
  }
  
  AVCodec ff_eacmv_decoder = {
      .name           = "eacmv",
      .long_name      = NULL_IF_CONFIG_SMALL("Electronic Arts CMV video"),
      .type           = AVMEDIA_TYPE_VIDEO,
      .id             = AV_CODEC_ID_CMV,
      .priv_data_size = sizeof(CmvContext),
      .init           = cmv_decode_init,
      .close          = cmv_decode_end,
      .decode         = cmv_decode_frame,
      .capabilities   = AV_CODEC_CAP_DR1,
  };
  