quicktime-api

Hi Simon;

On 6-Sep-07, at 10:41 AM, Simon Raisin wrote:

> On 9/5/07, Milton Aupperle <[EMAIL PROTECTED]> wrote:
> This has nothing to do with what the VDIG delivers. In the Settings  
> Panel that indicates what you want the Sequence Grabber to deliver  
> when it's configured to record. So the SG will take whatever native  
> format the VDIG delivers and then compress it (if possible) using  
> your specified Compression Codec.
>
> Ok, I think I understand this now Milton - thank you.
>
> If you want to know what the VDIG can actually deliver try calling  
> VDGetCompressionTypes() and looking at the VDCompressionListHandle  
> that gets returned. The VDCompressionListHandle contains at least  
> one VDCompressionList structure and may contain more.
>
> Ok, upon initialization I iterate through the VDCompressionList  
> structs to determine what my VDIG is capable of delivering.
>
> Now that I know what is available, I'm still confused as to *where/ 
> when* I need to perform my desired setup (no compression, 100%  
> sharpness, 0% saturation, 15 fps, depth: 256 grays).

Don't forget that if you ask for 8 bit grayscale "none" or RAW Codec,  
your likely going to get something weird out especially if it uses  
the standard 8 bit Monochrome CLUT (Color Look Up Table) with a  
GWorld / PixMap / PixMapHandle.

When Apple developed the first Mac, they defined grayscale as being 0  
for white and 255 for Black, and all the shades of gray in between  
them via a CLUT. So if I wanted Black, I used a value of 255 and in  
the  CLUT look up table that generates an RGB of 0,0,0.

This is still true to day and if you use the Apple standard gray  
scale CLUT, then your values are reversed. Most savy developers now  
create a custom Clut that has 0 index mapped to RGB 0,0,0 black and  
255 being white (255,255,255 or 65535, 65535, 65535 for old QuickDraw  
RGB colors structs used in a CLUT). This preserves the original  
intent of the camera data (0 = darkest, 255 = lightest) and matches  
the RGB display on screen.

> Do I do this right when I initialize the SG or when I am creating  
> the decompression session for the first time?  (I think it is the  
> latter, but I am not sure).

Anything that changes the video format, video depth or image size  
should be done before you set up the decompression session. Also If  
your going to manipulate the VDIG directly behind the SG's back,  
don't forget to call SGVideoDigitizerChanged() so that the SG can  
update it's status too after your done.

> Thank you again for all your help - I'm waiting for you to write a  
> book so I can stop bothering you directly. :)

Writing a book would be pointless because everything will be  
trashed / obsolete / re-done with Leopard (which is still secret and  
us long time VDIG writers have NEVER been consulted on this at all).  
Then it will only be another 5 years before we have stable video  
capture again with some meager documentation, but that's the Mac  
pessimist in me. I've only been writing Mac software now for 24 years  
now, so what would I know about "Look and Feel",  "Quality and  
Assurance Testing" or "Developer Relations".

HTH..

Milton J. Aupperle
President
ASC - Aupperle Services and Contracting
Mac Software (Drivers, Components and Application) Specialist
#1005 - 815 14th Avenue. S.W.
Calgary Alberta T2R0N5
1-(403)-229-9456
[EMAIL PROTECTED]
www.outcastsoft.com
Proud Supporter of the "Party of Alberta"
http://www.partyofalberta.org/


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