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libavcodec/yop.c

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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     avcodec_get_frame_defaults(&s->frame);
00096     s->num_pal_colors = avctx->extradata[0];
00097     s->first_color[0] = avctx->extradata[1];
00098     s->first_color[1] = avctx->extradata[2];
00099 
00100     if (s->num_pal_colors + s->first_color[0] > 256 ||
00101         s->num_pal_colors + s->first_color[1] > 256) {
00102         av_log(avctx, AV_LOG_ERROR,
00103                "YOP: palette parameters invalid, header probably corrupt\n");
00104         return AVERROR_INVALIDDATA;
00105     }
00106 
00107     return 0;
00108 }
00109 
00110 static av_cold int yop_decode_close(AVCodecContext *avctx)
00111 {
00112     YopDecContext *s = avctx->priv_data;
00113     if (s->frame.data[0])
00114         avctx->release_buffer(avctx, &s->frame);
00115     return 0;
00116 }
00117 
00123 static void yop_paint_block(YopDecContext *s, int tag)
00124 {
00125     s->dstptr[0]                        = s->srcptr[0];
00126     s->dstptr[1]                        = s->srcptr[paint_lut[tag][0]];
00127     s->dstptr[s->frame.linesize[0]]     = s->srcptr[paint_lut[tag][1]];
00128     s->dstptr[s->frame.linesize[0] + 1] = s->srcptr[paint_lut[tag][2]];
00129 
00130     // The number of src bytes consumed is in the last part of the lut entry.
00131     s->srcptr += paint_lut[tag][3];
00132 }
00133 
00138 static int yop_copy_previous_block(YopDecContext *s, int copy_tag)
00139 {
00140     uint8_t *bufptr;
00141 
00142     // Calculate position for the copy source
00143     bufptr = s->dstptr + motion_vector[copy_tag][0] +
00144              s->frame.linesize[0] * motion_vector[copy_tag][1];
00145     if (bufptr < s->dstbuf) {
00146         av_log(s->avctx, AV_LOG_ERROR,
00147                "YOP: cannot decode, file probably corrupt\n");
00148         return AVERROR_INVALIDDATA;
00149     }
00150 
00151     s->dstptr[0]                        = bufptr[0];
00152     s->dstptr[1]                        = bufptr[1];
00153     s->dstptr[s->frame.linesize[0]]     = bufptr[s->frame.linesize[0]];
00154     s->dstptr[s->frame.linesize[0] + 1] = bufptr[s->frame.linesize[0] + 1];
00155 
00156     return 0;
00157 }
00158 
00163 static uint8_t yop_get_next_nibble(YopDecContext *s)
00164 {
00165     int ret;
00166 
00167     if (s->low_nibble) {
00168         ret           = *s->low_nibble & 0xf;
00169         s->low_nibble = NULL;
00170     }else {
00171         s->low_nibble = s->srcptr++;
00172         ret           = *s->low_nibble >> 4;
00173     }
00174     return ret;
00175 }
00176 
00180 static void yop_next_macroblock(YopDecContext *s)
00181 {
00182     // If we are advancing to the next row of macroblocks
00183     if (s->row_pos == s->frame.linesize[0] - 2) {
00184         s->dstptr  += s->frame.linesize[0];
00185         s->row_pos =  0;
00186     }else {
00187         s->row_pos += 2;
00188     }
00189     s->dstptr += 2;
00190 }
00191 
00192 static int yop_decode_frame(AVCodecContext *avctx, void *data, int *data_size,
00193                             AVPacket *avpkt)
00194 {
00195     YopDecContext *s = avctx->priv_data;
00196     int tag, firstcolor, is_odd_frame;
00197     int ret, i;
00198     uint32_t *palette;
00199 
00200     if (s->frame.data[0])
00201         avctx->release_buffer(avctx, &s->frame);
00202 
00203     ret = avctx->get_buffer(avctx, &s->frame);
00204     if (ret < 0) {
00205         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00206         return ret;
00207     }
00208 
00209     s->frame.linesize[0] = avctx->width;
00210 
00211     s->dstbuf     = s->frame.data[0];
00212     s->dstptr     = s->frame.data[0];
00213     s->srcptr     = avpkt->data + 4;
00214     s->row_pos    = 0;
00215     s->low_nibble = NULL;
00216 
00217     is_odd_frame = avpkt->data[0];
00218     firstcolor   = s->first_color[is_odd_frame];
00219     palette      = (uint32_t *)s->frame.data[1];
00220 
00221     for (i = 0; i < s->num_pal_colors; i++, s->srcptr += 3)
00222         palette[i + firstcolor] = (s->srcptr[0] << 18) |
00223                                   (s->srcptr[1] << 10) |
00224                                   (s->srcptr[2] << 2);
00225 
00226     s->frame.palette_has_changed = 1;
00227 
00228     while (s->dstptr - s->dstbuf <
00229            avctx->width * avctx->height &&
00230            s->srcptr - avpkt->data < avpkt->size) {
00231 
00232         tag = yop_get_next_nibble(s);
00233 
00234         if (tag != 0xf) {
00235             yop_paint_block(s, tag);
00236         }else {
00237             tag = yop_get_next_nibble(s);
00238             ret = yop_copy_previous_block(s, tag);
00239             if (ret < 0) {
00240                 avctx->release_buffer(avctx, &s->frame);
00241                 return ret;
00242             }
00243         }
00244         yop_next_macroblock(s);
00245     }
00246 
00247     *data_size        = sizeof(AVFrame);
00248     *(AVFrame *) data = s->frame;
00249     return avpkt->size;
00250 }
00251 
00252 AVCodec ff_yop_decoder = {
00253     "yop",
00254     AVMEDIA_TYPE_VIDEO,
00255     CODEC_ID_YOP,
00256     sizeof(YopDecContext),
00257     yop_decode_init,
00258     NULL,
00259     yop_decode_close,
00260     yop_decode_frame,
00261     .long_name = NULL_IF_CONFIG_SMALL("Psygnosis YOP Video"),
00262 };

Generated on Wed Apr 11 2012 07:31:35 for FFmpeg by  doxygen 1.7.1