What's the value of half-d1 for extras?

[rayvt]

What's the value of half-d1 for extras?
It doesn't really reduce the size of the m2v files, so there doesn't seem to be much of a benefit. I did some trials of one cell (1078 frames, 45 seconds), with CCE, and here's the sizes:
15,733,380 V03000400001005-0pct-hd1.m2v
16,035,388 V03000400001005-0pct-nohd1.m2v
12,018,976 V03000400001005-25pct-hd1.m2v
12,010,336 V03000400001005-25pct-nohd1.m2v

Going from fullsize to half-d1 only saves reduces the size by a only trivial amount, whereas changing the reduction from 00% to 25% reduces the filesize by about 24%.

[wmansir]

Try cutting the bitrate by 50% then encoding a clip with and without Half-D1.

The half-D1 encode has less detail because of the decreased resolution, but should have fewer encoding artifacts because it is encoding less information than the full-D1 clip.

[int 21h]

If you think about your overall size as a bucket of paint, and the resolution (d1 vs half-d1) as your canvas, its easier to make a mental picture of what's going on here.

The amount of paint you have stays constant when you only change the resolution, the difference lies in what wmansir said with the artifacts. Since you're only trying to paint half of the area, you should get much better 'coverage' from your paint. Of course, this is subject to what sort of image you're trying to paint as well :-p

Maybe its not that good of a metaphor after all.

[jdobbs]

As the "readme" tells you, if gives you more granularity. You can decide to reduce extras to half-d1, and then select "Steal Space From Extras" at a level you feel is right. You will also find it useful in discs that, when reencoded, result in poor encoding quality on the extras because it had barely enough bandwidth even on the original -- there are quite a few of those. If you stole space, or used half/half they may lose too much quality.

[TomBrooklyn]

As the "readme" tells you, if gives you more granularity.
Hi jdobbs,
Which readme is that? The "readme" in DVDRB under the "Help" menu didn't have it.


You will also find it useful in discs that, when reencoded, result in poor encoding quality on the extras because it had barely enough bandwidth even on the original
You mean Half D1 would be useful, but not Steal Space, right? Is that because it would make a "smaller canvas" so the "paint" would fill the space better?

[jdobbs]

Whenever I add/change something in DVD Rebuilder, I update the REBUILDER.TXT file. The most recent set of changes is always available in HELP/"Show Readme". But many, many changes are in the .TXT file.

Yes to your second question. Sometimes you'll find discs that have the extras encoded at very low bitrates on the original. The problem is that when you compress the disc (say 70%) -- the extras get blocky. By selecting Half-D1 you can get a better picture (although lower resolution) from the resulting bitrate reduction -- without having to take any bits from your feature.