Getting Grainy picture on DVD’s

[Terry Esslinger]

1. What format was your original footage?
2. Are you using the MainConcept MPeg2 encoder?
3. VBR or CBR? One pass or 2 pass?
4. How long is your project?
5 Are you rendering them to MPg2 in Vegas or in DVDA (if using DVDA)?
Ini other words , need more information.

[Rick Rintala]

The footage is Mini DV, shot with a Sony DSR PD170, good footage.

Main Concept MPEG2

VBR, 1 pass

Project footage was only 10 minutes

Rendering thewm in Vegas.

Any hints would be greatly appreciated. I am no expert so If you know better ways to do this, please feel free to steer me in the right dirtection.

Thanks

Rick Rintala
Flying Finn Video Services
Bedford Texas
http://www.flyingfinnvideo.com

[Terry Esslinger]

What were the bit rate settings?

[Mike Kujbida]

Since it’s only 10 min. long, bump your Avg. to 8,000,000 and your Min. to 4,800,000.
BTW, I set my Min. to at least 2,000,000 for any renders I do, even if the video is 2 hr. long.
It does help.

[Rick Rintala]

Mike,

Does the one pass, two pass option affect quality, file size, etc?

Rick Rintala
Flying Finn Video Services
Bedford Texas
http://www.flyingfinnvideo.com

[Mike Kujbida]

Rick, I couldn’t answer the question myself so I did some searching and came up with the following (credit to John Cline and John Meyer for the info). Hope it helps.

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If the video is under 74 minutes and you’re using 192kbps .AC3 audio, you can just use CBR at a rate of 8 megabits/sec and the encode will be the highest quality it can be.

Two pass is only really valid when you use variable bit rate (VBR) because you need to fit more than 74 minutes on a single layer disc. Using VBR, you set a minimum, maximum and average bitrate. The average bit rate determines the final file size. On the first pass, the encoder analyzes the file looking for places which need a higher bit rate, like those parts with high motion, very fine detail or video noise. It also looks for parts of the video which don’t need as high a bit rate and allocates the bits it can save from these parts to the parts which need them.

It’s a balancing act, take bits from here and allocate them there and over the length of the entire file make sure that the bit rate hits the average that you set.

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VBR vs. CBR will not affect space. The ONLY thing that affects the size of the MPEG-2 file is the average bitrate.

If you set it to, for example, 6,000,000 bps (average), you will get the same file size whether you encode in VBR or CBR. What’s more — and this is the one that surprises most people at first — you will get the same size whether you encode at 720×480, 320×240 or any other resolution.

The key in understanding this is to look at the name of the setting: Bits Per Second. What this says is that the encoder is going to use that many bits for every single second of video. When encoding a higher-resolution video (e.g., 720×480 instead of 320×240), fewer bits are available to create the intermediate “B” and “P” frames, so you get more motion artifacts (e.g., “mosquito noise”), but the video is sharper. It is an interesting tradeoff, and an especially important one to understand when encoding for the web.

It also doesn’t matter what frame rate you use. If you encode the video at 10, 15, 29.97, or 30 fps, the size of the file will still be determined ONLY by the average bit rate setting.