Another issue might be the codec used for decoding. If what you compare is a dv file - then decoding might be different in Vegas and Combustion dependend on which codec each software uses for decoding.
What if you use an uncompressed AVI file? - Same difference?

Marco

Duh...I shoulda thought of that. I use uncompressed or sequential tgas for exchange between most of my Vegas and 3rd party tools. Didn't even consider this one. Thanks for the reminder, Taliesin. 'Course, you're all over the codec thing all the time. I don't worry about codecs much any more. Not like we did 2 years ago and earlier.

Thanks.
I'm capturing clips using Vegas. The format comes up as 'DV/DVCPRO - NTSC'. This is uncompressed, so I'm not sure how codecs would come into it. Even if it was compressed, I always thought video codecs were system-based and the software just tapped into them, meaning the decoding would work out the same. Not true?

Combustion can render the viewport using OpenGL, but the differences with Vegas are the same no matter if OpenGL is on or off. I can't think of any other card settings that might be affecting it. Anybody know?

I know ideally I'd be previewing on an external monitor, but I don't have the setup unfortunately. And with things like colour correction, ideally I'd be getting the general gist of how it'll turn out on the PC monitor no matter what software I'm using anyway. Can you imagine if a JPEG looked different depending on the software you were using?

I can match the Combustion preview to Vegas using ViewLUT, and that's what I'm doing at the minute, but it's not an ideal situation. I'm really curious as to why it's happening in the first place.

Mark

>> The format comes up as 'DV/DVCPRO - NTSC'. This is uncompressed, so I'm not sure how codecs would come into it.

This is not uncompressed. When you captured a dv source via firewire using Vegas then your clips are dv compressed which is a 5:1 compression. Them are not recompressed by capturing but they are already compressed on the dv tape.
And this needs a decoding then for working in Combustion.

>> Even if it was compressed, I always thought video codecs were system-based and the software just tapped into them, meaning the decoding would work out the same. Not true?

Yes and no. There are some codecs which affect the luminance range on decoding and on encoding. Sony Pictures DV (which is used in Vegas) does NOT touch the luminance range of a dv signal. MS-DV does affect luminance. So does MainConcept DV if it is not well configured.

Try rendering a clip out of Vegas using the uncompressed template. Then you can be sure to exclude the decoding issue. Maybe this helps.

Marco

Thanks Marco.
So Vegas captures are compressed? I looked for a setting in the preferences but couldn't find one. Is there any way to capture uncompressed data?

I tried outputting an uncompressed file from Vegas. The resulting file looked more similar in Combustion, but still a little more contrast and darker.

Mark

Vegas captures aren't compressed, the video is compressed in the camera. Vegas via VidCap simply copies the compressed data from the camera into a file.
To compare the preview in both you should bring the clip into Vegas, render out as uncompressed AVI, bring that file into Vegas and Combustion to make a valid comparison. As no codec is now involved in the decoding you are making a comparison that bypasses the codec issue.

Bob.

Aldred, DV is a compressed format by itself. So Vegas captures what is already compressed at the camera level. When Vegas captures it doesn't change the video at all, but this is not uncompressed video. The video it is capturing is already compressed. The compression in terms of storage space is about 5:1. The way the video is compressed is miniDV stores less color/brightness information.

Uncompressed video is 4:4:4 and NTSC miniDV is 4:1:1 which means that miniDV is not storing all the chroma/luma information. More techincal info can be found here.

Vegas does its internal processing at 4:4:4. So you can render a file to uncompressed video to take into another program. Uncompressed video files will be very big.

Thanks for all the help. I'm beginning to understand. I'm from a CG background, and this is my first real step into video.

So it's not strictly codecs we're talking about here, but sampling formats? What is happening to image quality when I save from Vegas as uncompressed? Is it just a reformat of the data to 4:4:4?

Mark

Compression and sampling are two different things. Sampling refers to how the Y:U:V is sampled, compression refers to how the resulting data is compressed. Just to further confuse you you also need to consider bit depth, mostly video is 8 bit color res apart from very high end systems that work at 10 or 12 bit.
So rendering out as uncompressed doesn't help anything, what's lost is lost however it avoids the issue of how the different codecs might decode the compressed data.
If you need to know more, you'll need to do a fair bit of reading, it's all well explained on the web, just be warned, it can be a fair bit to digest and there is some dodgy information out there.

Bob.

Ok. Thanks. I think I'm getting there. The data on DV, the colour and luminance values are sampled at lower rates. But .... that leads me back to the subject of compression of data captured by Vegas. Like I mentioned, I can see 'DV/DVCPRO - NTSC' in the properties of the captured footage. I read the link busterkeaton gave me above (thanks) and it seems that this would mean the footage *is* compressed, and captured as is with Discrete Cosine Transform (DCT) compression intact. Rendering an uncompressed avi from Vegas gets rid of this DCT compression.

Am I getting this right?
Mark

combustion will default to using the micrsoft DV codec to read the Vegas rendered clips which will place anything you had at 100 ire to 108 ire.
IMO go between the 2 apps using 4:4:4 uncompressed either avi or QT ..
i find i get a little cleaner clips working in 4:4:4 color space in combustion even though the clips were originally 4:1:1 ..... if you use combustion alot you might look at the buying the microcosm codec ( approx $80) which is a 16 bit per channel 4:4:4:4 codec ( 6-12 mgs depending in clip) .... or others have suggested to me the huffy codec ( i think it's free and is 4:4:4) i have not tried it ... i do use the microcosm

for test results on different codec's ( most are QT based)
http://codecs.onerivermedia.com/
then click on the different color spaces 4:4:4 , 4:2:2 etc ...