Re: Testing with lossless codecs
Re: Testing with lossless codecs
- Subject: Re: Testing with lossless codecs
- From: Marijn Eken <email@hidden>
- Date: Mon, 10 Aug 2009 22:20:33 +0200
You are right Brian. Included with QT or FCP, there is no mathematically lossless 10-bit codec.
There are however two options you could give a go:
1) AJA (makers of Video I/O hardware) have a free download of their software codecs. One of them is AJA 10-bit RGB, which should do exactly what you're looking for. Provided that you won't suffer from any gamma shifts, which seems to haunt me (and lots of other people on teh internets) all the time.
2) A codec called None16 by Digital Anarchy. Which is the 16-bit version of None. It makes HUGE files of course, but it works. Search for it on Google, since it seems Digital Anarchy discontinued it.
Hope that helps.
Cheers,
Marijn
On Mon, Aug 10, 2009 at 9:44 PM, Brian Gardner
<email@hidden> wrote:
Thanks, Darrin.
There appears to be no way to test my plugins using
a lossless QuickTime codec.
I tried the Difference matte technique you suggested to test a
number of QuickTime codecs, including the Animation codec.
None of them were lossless. Actually, it's kind of scary
that QuickTime does not have a single codec that is completely lossless...
even the "uncompressed" were lossy.
I used a 10 bit DPX 1920x1080p 24.0 fps sequence as source footage,
which I've just received from a recent music video shoot, shot on a stage.
The goal is to convert it into a single QuickTime ".mov" file,
with lossless compression (or even no compression). I couldn't achieve that goal.
Here are the codecs that I tested:
Animation (at best setting) - truncates off the bottom 2 bits (10 bit - > 8 bit), which is lossy.
None - Exact same results as Animation. 8-bit only. truncated bottom 2 bits. Lossy.
(Differencing the Animation and None codecs to each other gives 0's-- exact match.)
FCP Uncompressed 422 10 bit - differences at all edges (to be expected, 444->422 issue)
DNxHD 10 bit 709 - Noisiest of these codecs. (Noisy into top 8 bits.) Blocking artifacts,
especially in the vertically oriented direction. Lossy.
Apple Pro Res HQ - slightly noisier than FCP Uncompressed 422, but similar 444->422 lossy results.
Apple Pro Res 4444 codec - least lossy of the codecs I tested. Appears to have saved full 10 bits.
(Did not just truncate down to 8. Possibly can do 16->16 bit?) Noisy in bottom bits, though. Lossy.
NOTE: The Apple Pro Res 4444 codec has a bug, in that it does not appear to do
the right thing if it is given an image that does not have an alpha channel.
And there is no option in the codec UI to automatically add a fully opaque alpha channel.
(It would be very nice to have that option.)
When I layer two copies of the SAME resulting ProRes 4444 video on top of each other,
and toggle visibility of the top layer On & Off -- they do not match!
There is a brightness/contrast difference, which appears to be stemming from the alpha.
For my 10 bit 444 source video, Pro Res 4444 was less lossy than "Uncompressed", "None", and "Animation".
"Lossless" QT codecs appear to only be lossless for 8 bit video, not anything above 8 bits.
Ditto for 444 video ... where even "Uncompressed" is quite lossy. Both were rather jarring surprises.
-- Brian
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