cinfo.CCIR601_sampling = true; // Seems to be mostly ignored by libjpeg, though.
jpeg_start_compress(&cinfo, true);
+ // This comment marker is private to FFmpeg. It signals limited Y'CbCr range
+ // (and nothing else).
+ jpeg_write_marker(&cinfo, JPEG_COM, (const JOCTET *)"CS=ITU601", strlen("CS=ITU601"));
+
JSAMPROW yptr[8], cbptr[8], crptr[8];
JSAMPARRAY data[3] = { yptr, cbptr, crptr };
for (unsigned y = 0; y < height; y += 8) {