Transcoding AVCHD to ProRes?

[User]

57 minutes ago, Axel said:

Yes, we had this before.

If your 8-bit camera records in broadcast range, it most probably means 16-235. The range between 236 and 255 is not clipped, it just doesn't show immediately because it's 'superwhite'. But the highlights can be recovered in your NLE by drawing 110 beneath 100, thereby remapping the original values by a gamma curve.

But:

If you let remap 5D2RGB the 235 of your recording to 1024 in 10-bit ProRes, you lose these 'illegal' values. That's what happens if you choose "Full Range" (sounds better, but isn't).

That's what your images show - blown out sun in full range.

Only very few 8-bit cameras record full range, among them the 5Ds, if I don't err. 

What about floating point?

The 10-bit of ProRes don't help much if a mere 8-bit image is the source. With 32-bit computing, an 8-bit image is treated as if it had a much higher bit depth. There are practically no 'rounding errors'. An 8-bit clip transcoded to ProRes remains an 8-bit image, there is no wizardry going on. Only with floating point precision you can avoid banding and other artifacts during grading - with AVCHD originals just as good as with ProRes copies. The latter are just more edit-friendly, and that's the extend of it.

There are some very good tutorials on the web that prove these simple facts, but I am on a train with a cell phone and won't search for them now.

Maybe someone bright can confirm?
My understanding is that 5DtoRGB 'Full Range' uses the full 0-255. So everything that was recorded by the C100 MkII is retained in the transcoded ProRes material. This is what I'm sticking to until I hear otherwise.

[Axel]

4 hours ago, User said:

Maybe someone bright can confirm?
My understanding is that 5DtoRGB 'Full Range' uses the full 0-255. So everything that was recorded by the C100 MkII is retained in the transcoded ProRes material. This is what I'm sticking to until I hear otherwise.

Oh, yes, it may well be that the excellent C100 records full range, it will at least do so in C-Log ("Cinema-Lock"), because otherwise a log profile made little sense. But let this be confirmed by "someone bright".

Let me quote from the 5D2RGB manual:

Quote

Luminance Range: This setting tells 5DtoRGB whether to interpret the color range in your footage as full range (0-255) or broadcast range (16-235). The correct setting will depend on the camera used. Some cameras, like Canon HDSLRs, shoot using full-range color. On the other hand, the Panasonic DMC-GH2 shoots using broadcast range color. If you select "ITU-R BT.709" as your decoding matrix, "Broadcast Range" will be selected automatically. 

But even if "full range" is the correct setting for your camera and profile, you should think about what they say here:

Quote

It also recognizes Canon's full range 8 bit YCbCr values (0-255), avoiding clipping and the resulting loss of picture information. The resulting files are the absolute highest quality you'll ever get out of the camera. In fact, you could argue that they're even better than the camera originals since they've undergone high quality chroma smoothing.

How on earth can a copy be better than the original? Chroma smoothing? You lose information by that. Yes, I know that many posted "proof" that 5D2RGB did some magic on original footage that showed banding. If that's what you are looking for, a baked-in banding-filter, go ahead. 

The whole point of using ProRes is that it's visually lossless. Compared to the original, you can't tell the difference. But it doesn't add color depth or chroma samples, otherwise it would be absolutely lossy. 

The ancient *religion* of Adobe to always use the native files to compute changes is theoretically the only way to preserve full quality. There is a loss with ProRes, but no one can see it, and it's many advantages outweigh this hypothetic chance.

[User]

35 minutes ago, Axel said:

Oh, yes, it may well be that the excellent C100 records full range, it will at least do so in C-Log ("Cinema-Lock"), because otherwise a log profile made little sense. But let this be confirmed by "someone bright".

Let me quote from the 5D2RGB manual:

But even if "full range" is the correct setting for your camera and profile, you should think about what they say here:

How on earth can a copy be better than the original? Chroma smoothing? You lose information by that. Yes, I know that many posted "proof" that 5D2RGB did some magic on original footage that showed banding. If that's what you are looking for, a baked-in banding-filter, go ahead. 

The whole point of using ProRes is that it's visually lossless. Compared to the original, you can't tell the difference. But it doesn't add color depth or chroma samples, otherwise it would be absolutely lossy. 

The ancient *religion* of Adobe to always use the native files to compute changes is theoretically the only way to preserve full quality. There is a loss with ProRes, but no one can see it, and it's many advantages outweigh this hypothetic chance.

Axel, I can appreciate it that your trying to help and all but I wonder if you are going around in circles? Yes I read the 5DtoRGB manual before the transcode and, as I understood it, 'Full range' seemed the way to go. So that's where I went.

My comment on 'someone bright' wasn't aimed at you, I said this because what I sometimes see in this forum is that some folks are a tad excited to contribute though they may not have the hard facts. Nothing more, nothing less.

Maybe it's worth reminding ourselves that although we might like the world to be perfect, it isn't. I transcoded some material in the best way I knew how at the time, the world goes on.

[Stephen de Vere]

Yes, Full Range in 5DtoRGB is usually the safer way to go with footage from cameras that record a greater range than Legal / Broadcast Range of 16-235.

The trouble is that most modern cameras record using neither Full Range (0-255) nor Broadcast Range but instead use Extended Range (16-255) (and increasingly both Extended aa well as Broadcast depending on the setup and picture profile used) and 5DtoRGB has no option for correctly mapping values for footage that uses Extended Range.

If your camera is one of the many now that sometimes produces these 16-255 values (also known as super-whites) then by setting 'Full Range' in 5DtoRGB you will avoid highlight clipping that using the 'Broadcast Range' setting risks, but your luma values usually will still be shifted a little, which is generally thought not an ideal thing to do to master 8-bit video recordings that are going to be graded etc.