https://web.archive.org/web/20170822225433/http://www.mysterybox.us/blog/201... ==== As slightly more concerning consideration, however, is the availability of high quality 12+ bit codecs for use in intermediate files. Obviously any codec using 8 bits / channel only are out of the question for HDR masters or intermediates, since 10 bits are required by all HDR standards. 10 bit encoding is completely fine for mastering space, and codecs like ProRes 422, DNxHR HQX/444, 10 bit DPX, or any of the many proprietary ‘uncompressed’ 10 bit formats you’ll find with most NLEs and color correction softwares should all work effectively. However, if you’re considering which codecs to use as intermediates for HDR work, especially if you’re planning on an SDR down-grade from these intermediates, 12 bits per channel as a minimum is important. I don’t want to get sidetracked into the math behind it, but just a straight cross conversion from PQ HDR into SDR loses about ½ bit of precision in data scaling, and another ¼ - ½ bit precision in redistributing the values to the gamma 2.4 curve, leaving a little more 1 bit of precision available for readjusting the contrast curve (these are not uniform values). So, to end up with an error-free 10 bit master (say, for UHD broadcast) you need to encode 12 bits of precision into your HDR intermediate. ProRes 4444 / 4444 (XQ), DNxHR 444, 12 bit DPX, Cineform RGB 12 bit, 16 bit TIFFs, or OpenEXR (Half Precision) are all suitable intermediate codecs,** though it’s important to double check all of your downstream applications to make sure that whichever you pick will work later. Similarly, any of these codecs should be suitable for mastering, with the possibility of creating a cross converted grade from the master later. ==== hm, so even if swscale from rgba32f timeline to libavcodec still buggy we can just use cingg's built-in tiff/exr output, I guess? Strangely for now those blogs are not linked to site? I found link while looking inside HDR.zip provided at doom9 forums https://spaces.hightail.com/space/nEaXy 91 Mb!