STUMP THE PRO RES GURUS…

[Jeremy Garchow]

First of all, ProRes is bigger than DVCPRo HD. ProRes is not an offline codec, actually quite the opposite.

The brightness shift you are seeing in your canvas, but not on your production monitor, correct? If so, try turning off the range check, (control-z or File > Range Check > Off).

Jeremy

[Jim Blokland]

Hey Jeremy:

Thanks for the response. The reason I’m interested in using Pro Res as an offline codec, is that it actually gives me a file size about one third smaller than a transcode to DV 25 — and it actually plays back off my 3G iPod! — and even though the raster size is technically bigger, the 960 x 720 anamorphic DVCPRO HD frame transcodes perfectly into 1280 x 720 square pixels.

Unfortunately, the range check function was not on. (I’m not sure if the picture is changing on output to my production monitor, because I’ve just been doing these tests on my laptop — and probably will only use this codec as a solution to be portable…otherwise I’ll just edit 720p DVCPRO HD natively on my Dual G5 desktop)

Any other ideas welcome. If there was any way to get this working, it would be pretty cool.

Best, JIM.

OSX.4.3
Dual 2.7 G5
3.5 GB RAM
Radeon X800 XT
Kona 2 / K-Box
Seritek 1.2 TB RAID
AVID XPRESS PRO/MOJO

[Gary Adcock]

[Jim Blokland] “Any other ideas welcome. If there was any way to get this working, it would be pretty cool.”

I am with Jeremy here, this seems like a backwards way to go.

But the bigger issue you are having is that you are transcoding from HD’s Rec709 colorspace to SD;s default Rec 601 when you change the format size to something that is considered SD in Size by QT.

That could be the reason for the color shift.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows

[Jeremy Garchow]

[Jim Blokland] “that it actually gives me a file size about one third smaller than a transcode to DV 25”

That seems pretty impossible. DVCPro HD, 720p24 is barely bigger than dv25 so I can’t see how 10bit ProRes could be any smaller than considering that it’s over twice the bit rate. Even Pro Res regular (not HQ) has a higher bit rate than DVCPro HD.

As far as the color shift, Gary cold be on to something, but I bet you wouldn’t see it on a monitor, only in your canvas. You can edit DVCPro HD on a laptop all day every day. No need to transcode.

Jeremy

[Jim Blokland]

Hi guys:

Thanks for the thoughtful responses. First of all, I must apologize — got some of my file size numbers mixed up. Here’s the deal:

When I take a 538 MB (1.5 min) DVCPRO HD clip and transcode to:

Pro Res (normal) 1280 x 720 = 621 MB
Pro Res at 720 x 405 = 398 MB
DV 25 720 x 480 = 285 MB

So you’re right, the DV 25 is the lowest file size. Although, the Pro Res smaller version looks the sharpest — except for the brightness or gamma shift. I don’t get this when I transcode to Pro Res HD 24p, only when I lower the pixel count…

Perhaps I’m causing more trouble than it’s worth and should just stay in DVCPRO HD and leave it at that. It would be sweet though to get the entire feature on one 500 GB drive. I could almost do that if the Pro Res solution worked.

Best, JIM.

OSX.4.3
Dual 2.7 G5
3.5 GB RAM
Radeon X800 XT
Kona 2 / K-Box
Seritek 1.2 TB RAID
AVID XPRESS PRO/MOJO

[Neil Ryan]

[Jim Blokland] “it looks fine but when I hit play, the brightness of the shot jumps higher than when parked — and when parked, it looks exactly like the original in terms of brightness/gamma.”

This issue can occur based on your Timeline Settings.
check under the ‘Video Processing’ tab for the ‘Process Maximum White as:’ setting.
Toggle it and see if that makes a difference.

Neil.

– – – – – – – – –
Neil Ryan
Post Production
The Pod Multimedia
http://www.the-pod.com.au
– – – – – – – – –

[Jim Blokland]

Well, after further puttering, I’ve discovered that no, toggling the white/super-white settings does not make any difference. I tried another codec with a twist — the Photo JPEG HD setting, with the pixel size set at 960×720 and with the quality set at 50%, and while the file size got down to 169 MB (from 583 MB — and the picture looks pretty decent), there is still a shift on playback — this time more of a colour shift. I suspect Gary is right, that transcoding to a different colourspace just causes issues that can’t be corrected.

So, if I want to have a cutting version for offline that is DVCPRO HD size, but about 1/3 the data, I could go the Photo JPEG route and live with the colour shenanigans. Or I can just cut with DVCPRO HD selects on my portable drive and call it a day.

Many thanks to all who listened, offered advice, and showed patience with my experimentation!

Best, JIM.

OSX.4.3
Dual 2.7 G5
3.5 GB RAM
Radeon X800 XT
Kona 2 / K-Box
Seritek 1.2 TB RAID
AVID XPRESS PRO/MOJO