Libav 0.7.1
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00001 00026 #include "libavutil/intreadwrite.h" 00027 #include "libavutil/imgutils.h" 00028 00029 #include "avcodec.h" 00030 #include "get_bits.h" 00031 00032 typedef struct YopDecContext { 00033 AVFrame frame; 00034 AVCodecContext *avctx; 00035 00036 int num_pal_colors; 00037 int first_color[2]; 00038 int frame_data_length; 00039 int row_pos; 00040 00041 uint8_t *low_nibble; 00042 uint8_t *srcptr; 00043 uint8_t *dstptr; 00044 uint8_t *dstbuf; 00045 } YopDecContext; 00046 00047 // These tables are taken directly from: 00048 // http://wiki.multimedia.cx/index.php?title=Psygnosis_YOP 00049 00056 static const uint8_t paint_lut[15][4] = 00057 {{1, 2, 3, 4}, {1, 2, 0, 3}, 00058 {1, 2, 1, 3}, {1, 2, 2, 3}, 00059 {1, 0, 2, 3}, {1, 0, 0, 2}, 00060 {1, 0, 1, 2}, {1, 1, 2, 3}, 00061 {0, 1, 2, 3}, {0, 1, 0, 2}, 00062 {1, 1, 0, 2}, {0, 1, 1, 2}, 00063 {0, 0, 1, 2}, {0, 0, 0, 1}, 00064 {1, 1, 1, 2}, 00065 }; 00066 00071 static const int8_t motion_vector[16][2] = 00072 {{-4, -4}, {-2, -4}, 00073 { 0, -4}, { 2, -4}, 00074 {-4, -2}, {-4, 0}, 00075 {-3, -3}, {-1, -3}, 00076 { 1, -3}, { 3, -3}, 00077 {-3, -1}, {-2, -2}, 00078 { 0, -2}, { 2, -2}, 00079 { 4, -2}, {-2, 0}, 00080 }; 00081 00082 static av_cold int yop_decode_init(AVCodecContext *avctx) 00083 { 00084 YopDecContext *s = avctx->priv_data; 00085 s->avctx = avctx; 00086 00087 if (avctx->width & 1 || avctx->height & 1 || 00088 av_image_check_size(avctx->width, avctx->height, 0, avctx) < 0) { 00089 av_log(avctx, AV_LOG_ERROR, "YOP has invalid dimensions\n"); 00090 return -1; 00091 } 00092 00093 avctx->pix_fmt = PIX_FMT_PAL8; 00094 00095 s->num_pal_colors = avctx->extradata[0]; 00096 s->first_color[0] = avctx->extradata[1]; 00097 s->first_color[1] = avctx->extradata[2]; 00098 00099 if (s->num_pal_colors + s->first_color[0] > 256 || 00100 s->num_pal_colors + s->first_color[1] > 256) { 00101 av_log(avctx, AV_LOG_ERROR, 00102 "YOP: palette parameters invalid, header probably corrupt\n"); 00103 return AVERROR_INVALIDDATA; 00104 } 00105 00106 return 0; 00107 } 00108 00109 static av_cold int yop_decode_close(AVCodecContext *avctx) 00110 { 00111 YopDecContext *s = avctx->priv_data; 00112 if (s->frame.data[0]) 00113 avctx->release_buffer(avctx, &s->frame); 00114 return 0; 00115 } 00116 00122 static void yop_paint_block(YopDecContext *s, int tag) 00123 { 00124 s->dstptr[0] = s->srcptr[0]; 00125 s->dstptr[1] = s->srcptr[paint_lut[tag][0]]; 00126 s->dstptr[s->frame.linesize[0]] = s->srcptr[paint_lut[tag][1]]; 00127 s->dstptr[s->frame.linesize[0] + 1] = s->srcptr[paint_lut[tag][2]]; 00128 00129 // The number of src bytes consumed is in the last part of the lut entry. 00130 s->srcptr += paint_lut[tag][3]; 00131 } 00132 00137 static int yop_copy_previous_block(YopDecContext *s, int copy_tag) 00138 { 00139 uint8_t *bufptr; 00140 00141 // Calculate position for the copy source 00142 bufptr = s->dstptr + motion_vector[copy_tag][0] + 00143 s->frame.linesize[0] * motion_vector[copy_tag][1]; 00144 if (bufptr < s->dstbuf) { 00145 av_log(s->avctx, AV_LOG_ERROR, 00146 "YOP: cannot decode, file probably corrupt\n"); 00147 return AVERROR_INVALIDDATA; 00148 } 00149 00150 s->dstptr[0] = bufptr[0]; 00151 s->dstptr[1] = bufptr[1]; 00152 s->dstptr[s->frame.linesize[0]] = bufptr[s->frame.linesize[0]]; 00153 s->dstptr[s->frame.linesize[0] + 1] = bufptr[s->frame.linesize[0] + 1]; 00154 00155 return 0; 00156 } 00157 00162 static uint8_t yop_get_next_nibble(YopDecContext *s) 00163 { 00164 int ret; 00165 00166 if (s->low_nibble) { 00167 ret = *s->low_nibble & 0xf; 00168 s->low_nibble = NULL; 00169 }else { 00170 s->low_nibble = s->srcptr++; 00171 ret = *s->low_nibble >> 4; 00172 } 00173 return ret; 00174 } 00175 00179 static void yop_next_macroblock(YopDecContext *s) 00180 { 00181 // If we are advancing to the next row of macroblocks 00182 if (s->row_pos == s->frame.linesize[0] - 2) { 00183 s->dstptr += s->frame.linesize[0]; 00184 s->row_pos = 0; 00185 }else { 00186 s->row_pos += 2; 00187 } 00188 s->dstptr += 2; 00189 } 00190 00191 static int yop_decode_frame(AVCodecContext *avctx, void *data, int *data_size, 00192 AVPacket *avpkt) 00193 { 00194 YopDecContext *s = avctx->priv_data; 00195 int tag, firstcolor, is_odd_frame; 00196 int ret, i; 00197 uint32_t *palette; 00198 00199 if (s->frame.data[0]) 00200 avctx->release_buffer(avctx, &s->frame); 00201 00202 ret = avctx->get_buffer(avctx, &s->frame); 00203 if (ret < 0) { 00204 av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); 00205 return ret; 00206 } 00207 00208 s->frame.linesize[0] = avctx->width; 00209 00210 s->dstbuf = s->frame.data[0]; 00211 s->dstptr = s->frame.data[0]; 00212 s->srcptr = avpkt->data + 4; 00213 s->row_pos = 0; 00214 s->low_nibble = NULL; 00215 00216 is_odd_frame = avpkt->data[0]; 00217 firstcolor = s->first_color[is_odd_frame]; 00218 palette = (uint32_t *)s->frame.data[1]; 00219 00220 for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3) 00221 palette[i + firstcolor] = (s->srcptr[0] << 18) | 00222 (s->srcptr[1] << 10) | 00223 (s->srcptr[2] << 2); 00224 00225 s->frame.palette_has_changed = 1; 00226 00227 while (s->dstptr - s->dstbuf < 00228 avctx->width * avctx->height && 00229 s->srcptr - avpkt->data < avpkt->size) { 00230 00231 tag = yop_get_next_nibble(s); 00232 00233 if (tag != 0xf) { 00234 yop_paint_block(s, tag); 00235 }else { 00236 tag = yop_get_next_nibble(s); 00237 ret = yop_copy_previous_block(s, tag); 00238 if (ret < 0) { 00239 avctx->release_buffer(avctx, &s->frame); 00240 return ret; 00241 } 00242 } 00243 yop_next_macroblock(s); 00244 } 00245 00246 *data_size = sizeof(AVFrame); 00247 *(AVFrame *) data = s->frame; 00248 return avpkt->size; 00249 } 00250 00251 AVCodec ff_yop_decoder = { 00252 "yop", 00253 AVMEDIA_TYPE_VIDEO, 00254 CODEC_ID_YOP, 00255 sizeof(YopDecContext), 00256 yop_decode_init, 00257 NULL, 00258 yop_decode_close, 00259 yop_decode_frame, 00260 .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"), 00261 };