пн, 9 сент. 2024 г., 23:04 Andrew Randrianasulu <randrianas...@gmail.com>:
> > > пн, 9 сент. 2024 г., 18:06 Andrew Randrianasulu <randrianas...@gmail.com>: > >> Looking at libswscale/swscale.c (due to >> https://trac.ffmpeg.org/ticket/11182#comment:5) I do not understand >> how it works :) >> >> why shits to 11 and to 12 ? >> >> // FIXME all pal and rgb srcFormats could do this conversion as well >> // FIXME all scalers more complex than bilinear could do half of this >> transform >> static void chrRangeToJpeg_c(int16_t *dstU, int16_t *dstV, int width) >> { >> int i; >> for (i = 0; i < width; i++) { >> dstU[i] = (FFMIN(dstU[i], 30775) * 4663 - 9289992) >> 12; // -264 >> dstV[i] = (FFMIN(dstV[i], 30775) * 4663 - 9289992) >> 12; // -264 >> } >> } >> >> static void chrRangeFromJpeg_c(int16_t *dstU, int16_t *dstV, int width) >> { >> int i; >> for (i = 0; i < width; i++) { >> dstU[i] = (dstU[i] * 1799 + 4081085) >> 11; // 1469 >> dstV[i] = (dstV[i] * 1799 + 4081085) >> 11; // 1469 >> } >> } >> >> === >> can anyone knowledgeable write/add some more comments in code ? please :) >> > > > it seems that same code (under slightly different name) was living in > swscale_template.c since at least 2009 ... > > > > https://git.ffmpeg.org/gitweb/ffmpeg.git/blobdiff/c1977fbbd7d1e7825010e301fa236e910b760aab..bae76dc3eb6e5cd07f5881092d375ddc0270f693:/libswscale/swscale_template.c > and it was commited in 2008: https://git.ffmpeg.org/gitweb/ffmpeg.git/commit/6bc0c7928a386d5cf99c198ec1b795aff6bf7656 Fix jpeg yuv. author Michael Niedermayer <michae...@gmx.at> Mon, 8 Sep 2008 15:36:38 +0300 (12:36 +0000) committer Michael Niedermayer <michae...@gmx.at> Mon, 8 Sep 2008 15:36:38 +0300 (12:36 +0000) commit 6bc0c7928a386d5cf99c198ec1b795aff6bf7656 tree a90c126c5d92e65bfe4ad9dac24473eaae8464ed tree parent f7b1d72f45c97f3fc57632a0a23d01cee51c4a4e commit | diff Fix jpeg yuv. Fixes issue504. Originally committed as revision 27547 to svn:// svn.mplayerhq.hu/mplayer/trunk/libswscale hm, but this does not make it less opaque for me ;) I guess it was working for all those years .. mostly? > > _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
