Quality loss when rendering mini-DVD

[Johan Lundqvist]

Hi!

Every clip that I’ve edited had a variable bitrate of 9 100 000 before I started working with it. I don’t know if you’ve read the whole thread, but if I set the bitate to vbr 9 100 000 (as max) the “no recompression”-sign show during most of the rendering. The problems is that my cuts look horrible if i render with that bitrate. This is because the cuts are not at the I-frames as far as I can understand. If all my cuts were at I-frames, then the “no recompression”-sign would show during the whole rendering process and I would not loose anything at all during rendering. Since Vegas has no way of showing where the I-frames are, most of my cuts are not at I-frames.

Because of this, I’ve decided to render my movie with another bitrate than vbr 9 100 000 (max).

If I choose for example: Variable bitrate (max 9 500 000, average 6 000 000, minimum 192 000); then there is some quality loss across the whole movie (and the “no recompression”-sign is not constant during rendering), but the cuts look good.

My .mov-files are not fully downloaded yet. I’ll get back to you when they are.

[Bill Goyette]

I want to thank John for explaining this in great detail. I have a Panasonic SDR-H60 HDD camcorder that records directly to hard disk in MPEG-2 format (704×480). I have been recording at the HQ setting and editing in Vegas Pro 8c. Even rendering at the highest quality settings, the results were clearly degraded from the original. However, I have figured out the settings to force no compression loss, except for cuts / fades and FX:

Project properties need to match aspect ratio, but the other settings here do not seem to matter.
The important thing is the output render template match…I am also streaming out the audio in one shot, no separate stream:

Source video at 4:3, HQ to 4:3 NTSC DVD:
Rendering settings (start with DVD NTSC)edit to these settings:
Project Tab: Best
Video Tab: 704 x 480 (panasonic format), Max: 9,510,00 bps, Ave: 6,000,000 bps, Min: 4,200,000 bps
Advanced Video: no change
Audio: up rate to 384 kbps (little higher quality, original is Dolby AC3)
System: no change.

Source video at 16:9, HQ to 16:9 NTSC DVD:
Same as above except:
Project properties to widescreen DVD (1.2121) aspect ratio.
Either set media switch for all source media on timeline to turn off “Maintain Aspect Ratio”. This will force the media to fill the widescreen template. (16:9 or 4:3 footage from Panasonic camcorder looks the same to vegas, and the media defaults to 4:3 unless the properties for each clip are set individually, I found it much faster to group select and turn off the “Maintain Aspect Ratio” switch).
Or set make sure the properties for each clip are set to widescreen.
Rendering settings: same as above except select 16:9 on the video tab.

Results are very good, but raising the minimum compression rate, the transitions and cuts are pretty good, and overall, the results are much better than a re-render, even at highest quality rates.

Thanks again for the discussion and I hope this helps someone else using a mini-DVD or HDD camcorder.