On Wed, Sep 11, 2024 at 3:21 AM Michael Niedermayer <mich...@niedermayer.cc> wrote: > > Hi > > On Wed, Sep 11, 2024 at 02:45:59AM +0300, Andrew Randrianasulu wrote: > > I can't find entry about it in ffmpeg/MAINTAINERS > > I do try to maintain swscale. But iam surely happy if others help > If you have a patch that needs to be reviewed or applied i can look at it
well, sadly I do not have any patches because I do not even understand how chrRangeToJpeg_c works (I think I traced ~same code back to 2008 when it was introduced to fix jpeg's full range yuv) https://git.ffmpeg.org/gitweb/ffmpeg.git/blob/HEAD:/libswscale/swscale.c line 159 I wonder why two other functions look different ( lumRangeToJpeg16_c vs lumRangeToJpeg_c - I assumed some shit by 4 should be there <according to stackoverflow > but 4769U ? static void chrRangeToJpeg_c(int16_t *dstU, int16_t *dstV, int width) 160 { 161 int i; 162 for (i = 0; i < width; i++) { 163 dstU[i] = (FFMIN(dstU[i], 30775) * 4663 - 9289992) >> 12; // -264 164 dstV[i] = (FFMIN(dstV[i], 30775) * 4663 - 9289992) >> 12; // -264 165 } 166 } 167 168 static void chrRangeFromJpeg_c(int16_t *dstU, int16_t *dstV, int width) 169 { 170 int i; 171 for (i = 0; i < width; i++) { 172 dstU[i] = (dstU[i] * 1799 + 4081085) >> 11; // 1469 173 dstV[i] = (dstV[i] * 1799 + 4081085) >> 11; // 1469 174 } 175 } 176 177 static void lumRangeToJpeg_c(int16_t *dst, int width) 178 { 179 int i; 180 for (i = 0; i < width; i++) 181 dst[i] = (FFMIN(dst[i], 30189) * 19077 - 39057361) >> 14; 182 } 183 184 static void lumRangeFromJpeg_c(int16_t *dst, int width) 185 { 186 int i; 187 for (i = 0; i < width; i++) 188 dst[i] = (dst[i] * 14071 + 33561947) >> 14; 189 } 190 191 static void chrRangeToJpeg16_c(int16_t *_dstU, int16_t *_dstV, int width) 192 { 193 int i; 194 int32_t *dstU = (int32_t *) _dstU; 195 int32_t *dstV = (int32_t *) _dstV; 196 for (i = 0; i < width; i++) { 197 dstU[i] = (FFMIN(dstU[i], 30775 << 4) * 4663 - (9289992 << 4)) >> 12; // -264 198 dstV[i] = (FFMIN(dstV[i], 30775 << 4) * 4663 - (9289992 << 4)) >> 12; // -264 199 } 200 } 201 202 static void chrRangeFromJpeg16_c(int16_t *_dstU, int16_t *_dstV, int width) 203 { 204 int i; 205 int32_t *dstU = (int32_t *) _dstU; 206 int32_t *dstV = (int32_t *) _dstV; 207 for (i = 0; i < width; i++) { 208 dstU[i] = (dstU[i] * 1799 + (4081085 << 4)) >> 11; // 1469 209 dstV[i] = (dstV[i] * 1799 + (4081085 << 4)) >> 11; // 1469 210 } 211 } 212 213 static void lumRangeToJpeg16_c(int16_t *_dst, int width) 214 { 215 int i; 216 int32_t *dst = (int32_t *) _dst; 217 for (i = 0; i < width; i++) { 218 dst[i] = ((int)(FFMIN(dst[i], 30189 << 4) * 4769U - (39057361 << 2))) >> 12; 219 } 220 } 221 222 static void lumRangeFromJpeg16_c(int16_t *_dst, int width) 223 { 224 int i; 225 int32_t *dst = (int32_t *) _dst; 226 for (i = 0; i < width; i++) 227 dst[i] = (dst[i]*(14071/4) + (33561947<<4)/4)>>12; 228 } ===== I have very limited understanding how it was supposed to work , apart from recognizing 16-bit long datatypes as function params ... can you leave few words in source code explaining how it works? > > > > > > bugs meanwhile exist > > > > https://trac.ffmpeg.org/ticket/3345 > > https://trac.ffmpeg.org/ticket/7978 > > I was not aware of these and ATM i dont have time but > these smell like some constant somewhere is a little off > > thx > > [...] > -- > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB > > What does censorship reveal? It reveals fear. -- Julian Assange > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
