Hi, Le sam. 28 sept. 2024 à 18:16, Ramiro Polla <ramiro.po...@gmail.com> a écrit : > I think you missed that the internal representation (the contents of > dst) is 15 bits for bit_depth <= 14, and 19 bits for bit_depth > 14. > It is confusing, but when I say bit depths > 14, I mean input bit > depths > 14, which have an internal representation of 19 bits (and > therefore the contents of dst are int32_t). Look at chrRangeToJpeg16_c > for example.
Yes I did miss these, even I suspected it was there: I mentioned I suspect the discussion would end up about the amount of casting and function prototypes. > For bit depth > 14, I had to raise the precision of the calculation in > order to respect the mpeg range. In this case, the shift is 18 bits > instead of 14, and the offset becomes greater than 32 bits. I don't know what the dst buffers are for (or their dynamics), but I have no problem accepting this is the way. > lum from 16 coeff 224260 (0x036c04) offset 8589631520 ( 0x01fffb6020) > chr from 16 coeff 229380 (0x038004) offset 8589672480 ( 0x01fffc0020) > lum to 16 coeff 306429 (0x04acfd) offset -10041292800 (-0x025681f800) > chr to 16 coeff 299589 (0x049245) offset -9817128960 (-0x0249258000) Yes as you said, only > 14 requires int32_t dst buffers, int32_t coeff and int64_t offset. I can understand you didn't want to bother with this rare case beyond having offset this large. > The API is indeed a bit confusing because it is shared for all bit > depths. It should be: > (int16_t *dst, int width, uint16_t coeff, int32_t offset) for bit_depth <= 14 > and > (int32_t *dst, int width, uint32_t coeff, int64_t offset) for bit_depth > 14 My point, but cf. just above. Except maybe, use ptrdiff_t for width, to avoid the Win64 ABI woes. In any case, I didn't follow well enough the complete changes, and I didn't look for the corresponding SIMD changes I was also concerned with. But given the above, it must be fine. _______________________________________________ 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".
