Andrew Kolakowski wrote:If you want margins than shoot limited range. 16-255 makes not much sense for me. One end has margin, another not?
16-255 has to be treated in this case as full range (no other option), so in case of Rec.709 signal your white level is going be wrong. You're asking for one end to be limited, but other full. Strange combination.
Strange or not, that is how most 'consumer' and lower-end pro-line camcorders record HD-AVC, and now 4K AVC, and with no option to change that.
Andrew Kolakowski wrote:How are you going to flag such a strange thing like 16-255 for proper automated transcoding? We have issues just with limited v full. There is no existing spec for such a thing, so it has to b treated as full range, so you may as well extend black to 0.
If you mean transcoding with the Transcode function in Resolve. Well here's what I do. Taking 1080/30p HD-AVC.mp4 clips off my Canon HF-G30 as an example. If I bring the native clips into Resolve and let 'Auto' Data Levels interpret them, they are assigned at 'Video' levels. So if I transcode to DNxHD.mov or Cineform.mov using the Resolve Transcode function, yes, the original 16-255 range will get clamped to limited range 16-235 (10-bit 64‒940). To avoid that, I go into Clip Attributes and change the Data Level to Full. That way, when transcoded the original 16-255 range is preserved. Then when bringing the transcode into the Media Pool I change the Data Level interpretation back to Video Levels. As you know one of the nice things about Resolve is that it always processes in the background at Full Data Levels with 32-bit float. So even when working at Video levels, where there may be apparent clamping of the 'super-whites', that data is not lost and is still available for pull-down if so desired. And finally, I will export out at Video levels.
As for transcoding to DNxHD or ProRes with ffmpeg, no special precautions are necessary. These clips carry the yuv420p designation, so ffmpeg merely passes through the original 16-255 range.
No, I don't think that processing the these 16-255 range native clips or transcodes at Full Data Levels, and bringing the black point down to zero is the right way to go. That would then make 255 'true white' which it is not; 235 is the true white point for this 16-255 range material - in other words it is effectively 16-235 Rec709 range, but allows for specular excursion into the 'superwhites'. Trust me, I've been around the houses on this.
As to what luminance range I would shoot on the Pana GH5, well that would depend on a number of factors, not least the target delivery platform.