TVPast Forums

manthing · #1 01-26-2006, 05:33 PM

lordsmurf, you wrote "You cannot "shrink" homemade discs without entirely destroying it's quality." in a previous topic/thread.

could you please elaborate?

i've been constructing dvds with about 3 shows and a menu which usually run a tad larger than a +5dvd.

so i then use dvdshrink to compress the above to fit within a +5dvd.

to me old & tired eyes, i don't see any loss of quality.

what tools do you use to notice the loss?

markatisu · #2 01-26-2006, 06:48 PM

That is a bit different. Mainly what Smurf was talking about is if you already have a DVD5 sized disc people are taking DVD Shrink and using that to make a "copy" which means Shrink is re-shrinking bits and pieces of something that is already under the limit and destroying parts of the video in the process

Its not the same thing as if you have make a dvd and its 6GB and you want to get it to 4.3GB, that is not what he is taking about though you have to be careful. For instance if you have 6gb of video and its on a setting like 4hr mode from a DVD recorder you DO NOT want to shrink it because the bitrate is as low as its going to go without turning to crap so you risk destroying it instead of just putting less episodes on a disc.

lordsmurf · #3 01-27-2006, 01:20 AM

MPEG encoding is really nothing more than advanced math.
- Encoders analyze video streams and then create fancy mathematical equations based on the source, creating a new video stream.
- Transcoders essentially re-calculate the equations, taking shortcuts or arbitrarily lowering certain values. Streams are not analyzed. You can basically only have a successfrul transcode on material that is clean and was exaggerated to being with (bitrate too high, for example).

Studio source is clean, and generally it's encoding bitrates/properties were exaggerated and over the top. Studios want to be 110% sure that the movies looks good. They usually do the same for tv shows, although some of the more recent sets seem to be lacking (Thundercats, Pokemon).

Homemade source is not clean. A transcode is not suggested on homemade material.

If your homemade source is too large, I suggest you re-encode it with Canopus Procoder before authoring a DVD. For already-authored DVDs, you can also use DVD Rebuilder with Canopus Procoder 2 as the encoder engine. It will decompile the DVD, re-encode the video, and then recompile the DVD.

I notice loss with my eyes. The computer (especially LCD monitors) are good for seeing noise, if you want to look for it. But I watch most of my stuff on normal tv screens between 20 and 35 inches.

There is a paper by HP on the topic online:
http://www.hpl.hp.com/personal/Susie...7/hpidc97.html