Picture quality "revelation"

Samus wrote on 5/27/2005, 5:00 PM
I have a music video for a DVD I am making, it is the master copy from a DVCAM tape. Anyway I downloaded the DV tape and burned it to a DVD. Looked great. However, for kicks I took the DV file and converted it to a maximum quality DivX file, burned it to a CD-R, and watched it on my XBox.

The DivX file looks SIGNIFICANTLY better than the DVD does. I am using 8MBPS with Architect 3!

Maybe I am an idiot and DivX is a newer encoder thus it looks better but I always thought DivX even at the highest setting was a WAY lower bitrate than DVD? I paused both videos and I couldn't believe how much sharper the DivX one looked over the DVD. Is there any explination for this?

Comments

BillyBoy wrote on 5/27/2005, 8:36 PM
Sure. It all depends on the file type and the codec used to compress it and of course the encoder itself. I too have seen very high quality DivX files and the same can be also said for Real Media and Microsoft's WMV format IF you use a high enough bit rate some compression schemes are better than others.

The "secret" if that's what you want to call it is MPEG-2 (what DVD's typically are) is old school while DivX uses newer MPEG-4 which is suppose to be a better compression scheme. The better it is, the better the quality. Bitrates are only one of several factors.
Peter Burn wrote on 5/27/2005, 8:57 PM
You got that right Bill! I am not sure what the future holds but suspect MPEG2 will go the way of MPEG1. I too have seen better results with DivX compressed videos played back through DivX-compatible DVD players (I have a Phillips Wal-mart special).

Peter
farss wrote on 5/28/2005, 3:11 PM
Certainly at the low bitrates that DVD players need the more advanced codecs perform better. Don't write off mpeg-1 and -2 though. DivX and mpeg-4 are designed to deliver the best results at low bitrates, unlike mpeg-2 once you get over a certain bitrate quality doesn't improve unlike mpeg-1 and -2 which is why although quite old systems they'll be with us for a very long time in high end broadcast equipment and the next generation of DVD players.

The biggest single impact on the qulaity of a DVD is the source material. If this was a typical band video shot on prosummer cameras I suspect part of the problem will be the amount of video noise. This plays havoc with mpeg-2 encoding as much of the bandwidth gets used up encoding the noise. Try reducing the noise before encoding, Mike Cash has a very good plug in for Vegas that can work wonders, alternatively a very small amount of the Median FX can help as can Black Restore as most of the noise is in the blacks.

Bob.
johnmeyer wrote on 5/28/2005, 6:24 PM
Actually, I bet you used the wrong template with Vegas to encode. Bitrate is only part of the equation in getting good quality. If you used Vegas' "Default Template" as the starting point, then even at a high bitrate, the quality may very well be poor. Make CERTAIN that you use one of the "DVD Architect" templates as the starting pont when encoding to MPEG-2. Then, choose the average bitrate. If you Have the quality slider set to 31 (which the default template does NOT do) and have the MPEG-2 average bitrate set to 8,000,000, you shouldn't be able to see much, if any difference between DV source material and the encoded results, except perhaps during transitions, smoke-filled or fog-enshrouded scenes. If you are seeing signficant differences, then you didn't do the encoding correctly.
Samus wrote on 5/29/2005, 12:52 AM
I don't really use a template with Vegas. I convert back to DV then let DVD Architect convert to MPEG.

The BIG difference I noticed like I said is when I pause the video. The DivX looked picture perfect. The DVD looks way way more blurry and I couldn't get a sharp image. The DVD looks awesome, don't get me wrong. Just not even close to the DiVX. Could it have something to do with DivX deinterlacing my video or something?

if it helps, the material are music videos (shot on actual film camera, big budget stuff) dubbed to DVCAM from their master copies.
johnmeyer wrote on 5/29/2005, 7:38 AM
Pausing video is not a good way to check quality. As you have already noted, you will see interlacing artifcats that have nothing to do whatsoever with how the video looks when played at normal speed. Deinterlacing video that is going to be played on an interlaced TV is a bad idea.
BillyBoy wrote on 5/29/2005, 8:16 AM
Like with many topics discussed in these forums its a matter of degree. For example I don't have any issues pausing a DVD, (nor should you) they are typically razor sharp, crisp and free of any artifacts. Again, without trying to look pretentious, its the quality of the source file you start with, YOUR skill in applying any necessary corrections during the creating phase, (over doing it or doing the wrong things is just as bad and doing no correction) and choice of encoders, bitrates and often overlook HOW (meaning on what) you view the finished project.

Again, not boasting, (ok, maybe a little) but DVD's I've authored using the DV NTSC tempates not fiddling around changing the bitrate when viewed on my 50 inch Panasonic plasma fed by a good quality upscaling DVD player look really good. Words from others that seen them are typically breathtaking, astonishing and similar adjectives. I'm not boasting about content, rather QUALITY of the content, ie how the DVD "looks" when played back. Many factors determine how good that quality will be.

In no particular order:

1. quality of source file
2. what adjustments/enhancements you make to it
3. shifts in color space or transcoding compression issues
4. encoder/codec/template
5. type/size of television other devices DVD played back on
6. your DVD player, how accurate its internal IDE settings are
7. cabling between DVD player and playback device, S video, component or digital
8. media quality/type/brand (minor)