FFmpeg: libavcodec/qpeg.c Source File

00001 /*
00002  * QPEG codec
00003  * Copyright (c) 2004 Konstantin Shishkov
00004  *
00005  * This file is part of FFmpeg.
00006  *
00007  * FFmpeg is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * FFmpeg is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with FFmpeg; if not, write to the Free Software
00019  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
00020  */
00021 
00027 #include "avcodec.h"
00028 
00029 typedef struct QpegContext{
00030     AVCodecContext *avctx;
00031     AVFrame pic;
00032     uint8_t *refdata;
00033 } QpegContext;
00034 
00035 static void qpeg_decode_intra(const uint8_t *src, uint8_t *dst, int size,
00036                             int stride, int width, int height)
00037 {
00038     int i;
00039     int code;
00040     int c0, c1;
00041     int run, copy;
00042     int filled = 0;
00043     int rows_to_go;
00044 
00045     rows_to_go = height;
00046     height--;
00047     dst = dst + height * stride;
00048 
00049     while((size > 0) && (rows_to_go > 0)) {
00050         code = *src++;
00051         size--;
00052         run = copy = 0;
00053         if(code == 0xFC) /* end-of-picture code */
00054             break;
00055         if(code >= 0xF8) { /* very long run */
00056             c0 = *src++;
00057             c1 = *src++;
00058             size -= 2;
00059             run = ((code & 0x7) << 16) + (c0 << 8) + c1 + 2;
00060         } else if (code >= 0xF0) { /* long run */
00061             c0 = *src++;
00062             size--;
00063             run = ((code & 0xF) << 8) + c0 + 2;
00064         } else if (code >= 0xE0) { /* short run */
00065             run = (code & 0x1F) + 2;
00066         } else if (code >= 0xC0) { /* very long copy */
00067             c0 = *src++;
00068             c1 = *src++;
00069             size -= 2;
00070             copy = ((code & 0x3F) << 16) + (c0 << 8) + c1 + 1;
00071         } else if (code >= 0x80) { /* long copy */
00072             c0 = *src++;
00073             size--;
00074             copy = ((code & 0x7F) << 8) + c0 + 1;
00075         } else { /* short copy */
00076             copy = code + 1;
00077         }
00078 
00079         /* perform actual run or copy */
00080         if(run) {
00081             int p;
00082 
00083             p = *src++;
00084             size--;
00085             for(i = 0; i < run; i++) {
00086                 dst[filled++] = p;
00087                 if (filled >= width) {
00088                     filled = 0;
00089                     dst -= stride;
00090                     rows_to_go--;
00091                     if(rows_to_go <= 0)
00092                         break;
00093                 }
00094             }
00095         } else {
00096             size -= copy;
00097             for(i = 0; i < copy; i++) {
00098                 dst[filled++] = *src++;
00099                 if (filled >= width) {
00100                     filled = 0;
00101                     dst -= stride;
00102                     rows_to_go--;
00103                     if(rows_to_go <= 0)
00104                         break;
00105                 }
00106             }
00107         }
00108     }
00109 }
00110 
00111 static const int qpeg_table_h[16] =
00112  { 0x00, 0x20, 0x20, 0x20, 0x18, 0x10, 0x10, 0x20, 0x10, 0x08, 0x18, 0x08, 0x08, 0x18, 0x10, 0x04};
00113 static const int qpeg_table_w[16] =
00114  { 0x00, 0x20, 0x18, 0x08, 0x18, 0x10, 0x20, 0x10, 0x08, 0x10, 0x20, 0x20, 0x08, 0x10, 0x18, 0x04};
00115 
00116 /* Decodes delta frames */
00117 static void qpeg_decode_inter(const uint8_t *src, uint8_t *dst, int size,
00118                             int stride, int width, int height,
00119                             int delta, const uint8_t *ctable, uint8_t *refdata)
00120 {
00121     int i, j;
00122     int code;
00123     int filled = 0;
00124     int orig_height;
00125 
00126     /* copy prev frame */
00127     for(i = 0; i < height; i++)
00128         memcpy(refdata + (i * width), dst + (i * stride), width);
00129 
00130     orig_height = height;
00131     height--;
00132     dst = dst + height * stride;
00133 
00134     while((size > 0) && (height >= 0)) {
00135         code = *src++;
00136         size--;
00137 
00138         if(delta) {
00139             /* motion compensation */
00140             while((code & 0xF0) == 0xF0) {
00141                 if(delta == 1) {
00142                     int me_idx;
00143                     int me_w, me_h, me_x, me_y;
00144                     uint8_t *me_plane;
00145                     int corr, val;
00146 
00147                     /* get block size by index */
00148                     me_idx = code & 0xF;
00149                     me_w = qpeg_table_w[me_idx];
00150                     me_h = qpeg_table_h[me_idx];
00151 
00152                     /* extract motion vector */
00153                     corr = *src++;
00154                     size--;
00155 
00156                     val = corr >> 4;
00157                     if(val > 7)
00158                         val -= 16;
00159                     me_x = val;
00160 
00161                     val = corr & 0xF;
00162                     if(val > 7)
00163                         val -= 16;
00164                     me_y = val;
00165 
00166                     /* check motion vector */
00167                     if ((me_x + filled < 0) || (me_x + me_w + filled > width) ||
00168                        (height - me_y - me_h < 0) || (height - me_y > orig_height) ||
00169                        (filled + me_w > width) || (height - me_h < 0))
00170                         av_log(NULL, AV_LOG_ERROR, "Bogus motion vector (%i,%i), block size %ix%i at %i,%i\n",
00171                                me_x, me_y, me_w, me_h, filled, height);
00172                     else {
00173                         /* do motion compensation */
00174                         me_plane = refdata + (filled + me_x) + (height - me_y) * width;
00175                         for(j = 0; j < me_h; j++) {
00176                             for(i = 0; i < me_w; i++)
00177                                 dst[filled + i - (j * stride)] = me_plane[i - (j * width)];
00178                         }
00179                     }
00180                 }
00181                 code = *src++;
00182                 size--;
00183             }
00184         }
00185 
00186         if(code == 0xE0) /* end-of-picture code */
00187             break;
00188         if(code > 0xE0) { /* run code: 0xE1..0xFF */
00189             int p;
00190 
00191             code &= 0x1F;
00192             p = *src++;
00193             size--;
00194             for(i = 0; i <= code; i++) {
00195                 dst[filled++] = p;
00196                 if(filled >= width) {
00197                     filled = 0;
00198                     dst -= stride;
00199                     height--;
00200                 }
00201             }
00202         } else if(code >= 0xC0) { /* copy code: 0xC0..0xDF */
00203             code &= 0x1F;
00204 
00205             for(i = 0; i <= code; i++) {
00206                 dst[filled++] = *src++;
00207                 if(filled >= width) {
00208                     filled = 0;
00209                     dst -= stride;
00210                     height--;
00211                 }
00212             }
00213             size -= code + 1;
00214         } else if(code >= 0x80) { /* skip code: 0x80..0xBF */
00215             int skip;
00216 
00217             code &= 0x3F;
00218             /* codes 0x80 and 0x81 are actually escape codes,
00219                skip value minus constant is in the next byte */
00220             if(!code)
00221                 skip = (*src++) + 64;
00222             else if(code == 1)
00223                 skip = (*src++) + 320;
00224             else
00225                 skip = code;
00226             filled += skip;
00227             while( filled >= width) {
00228                 filled -= width;
00229                 dst -= stride;
00230                 height--;
00231                 if(height < 0)
00232                     break;
00233             }
00234         } else {
00235             /* zero code treated as one-pixel skip */
00236             if(code)
00237                 dst[filled++] = ctable[code & 0x7F];
00238             else
00239                 filled++;
00240             if(filled >= width) {
00241                 filled = 0;
00242                 dst -= stride;
00243                 height--;
00244             }
00245         }
00246     }
00247 }
00248 
00249 static int decode_frame(AVCodecContext *avctx,
00250                         void *data, int *data_size,
00251                         const uint8_t *buf, int buf_size)
00252 {
00253     QpegContext * const a = avctx->priv_data;
00254     AVFrame * const p= (AVFrame*)&a->pic;
00255     uint8_t* outdata;
00256     int delta;
00257 
00258     if(p->data[0])
00259         avctx->release_buffer(avctx, p);
00260 
00261     p->reference= 0;
00262     if(avctx->get_buffer(avctx, p) < 0){
00263         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
00264         return -1;
00265     }
00266     outdata = a->pic.data[0];
00267     if(buf[0x85] == 0x10) {
00268         qpeg_decode_intra(buf+0x86, outdata, buf_size - 0x86, a->pic.linesize[0], avctx->width, avctx->height);
00269     } else {
00270         delta = buf[0x85];
00271         qpeg_decode_inter(buf+0x86, outdata, buf_size - 0x86, a->pic.linesize[0], avctx->width, avctx->height, delta, buf + 4, a->refdata);
00272     }
00273 
00274     /* make the palette available on the way out */
00275     memcpy(a->pic.data[1], a->avctx->palctrl->palette, AVPALETTE_SIZE);
00276     if (a->avctx->palctrl->palette_changed) {
00277         a->pic.palette_has_changed = 1;
00278         a->avctx->palctrl->palette_changed = 0;
00279     }
00280 
00281     *data_size = sizeof(AVFrame);
00282     *(AVFrame*)data = a->pic;
00283 
00284     return buf_size;
00285 }
00286 
00287 static av_cold int decode_init(AVCodecContext *avctx){
00288     QpegContext * const a = avctx->priv_data;
00289 
00290     a->avctx = avctx;
00291     avctx->pix_fmt= PIX_FMT_PAL8;
00292     a->pic.data[0] = NULL;
00293     a->refdata = av_malloc(avctx->width * avctx->height);
00294 
00295     return 0;
00296 }
00297 
00298 static av_cold int decode_end(AVCodecContext *avctx){
00299     QpegContext * const a = avctx->priv_data;
00300     AVFrame * const p= (AVFrame*)&a->pic;
00301 
00302     if(p->data[0])
00303         avctx->release_buffer(avctx, p);
00304 
00305     av_free(a->refdata);
00306     return 0;
00307 }
00308 
00309 AVCodec qpeg_decoder = {
00310     "qpeg",
00311     CODEC_TYPE_VIDEO,
00312     CODEC_ID_QPEG,
00313     sizeof(QpegContext),
00314     decode_init,
00315     NULL,
00316     decode_end,
00317     decode_frame,
00318     CODEC_CAP_DR1,
00319     .long_name = NULL_IF_CONFIG_SMALL("Q-team QPEG"),
00320 };