Suggestions for Bitrate/Resolution Table

[frell]

for people who try to fit 2 hour movies on one CD, the calculated bitrate can be quite low like 687. i usually encode to the same resolution as my DVD, but in cases like this i probably shouldn't, right? why? anyway...

what are some good rules of thumb for the bitrate to resolution relation for typical dvd's. for example?

bitrate: resolution reduction:
950+ 00%
900+ 05%
850+ 10%
800+ 15%
750+ 20%
700+ 25%
700- put on two cd's.

of course, this is for playback on large screens...

thanks in advance, frell

[khp]

This is purely a matter of opinion.

IMHO 950kbps is extremely low for a full resolution DVD rip 950000/(704*400@25fps)=0.1349 bpp. According to the most commenly accepted rule of thumb, you should try to stay resonably close to 0.20 bpp.

[frell]

taking the suggestion of wanting .2 bpp i did some calcs in excel. for both 25fps and 30fps.

for a 90 minute movie, the bitrate calc i use tells me 959 kbps. which since i don't downsamlpe my dvd's to 25 fps, i guess i should be reducing my resolution to 496x336...

kbps fps wpf hpf bpp wpf'' hpf'' bpp'
1950 30 704 464 0.20 704 464 0.20
1850 30 704 464 0.19 688 464 0.19
1750 30 704 464 0.18 672 448 0.19
1650 30 704 464 0.17 656 432 0.19
1550 30 704 464 0.16 640 416 0.19
1450 30 704 464 0.15 608 400 0.20
1350 30 704 464 0.14 592 400 0.19
1250 30 704 464 0.13 576 384 0.19
1200 30 704 464 0.12 560 368 0.19
1150 30 704 464 0.12 544 368 0.19
1100 30 704 464 0.11 528 352 0.20
1050 30 704 464 0.11 528 352 0.19
1000 30 704 464 0.10 512 336 0.19
950 30 704 464 0.10 496 336 0.19
900 30 704 464 0.09 480 320 0.20
850 30 704 464 0.09 464 320 0.19
800 30 704 464 0.08 464 304 0.19
750 30 704 464 0.08 448 288 0.19
700 30 704 464 0.07 432 288 0.19

kbps fps wpf hpf bpp wpf'' hpf'' bpp'
1550 25 704 464 0.19 688 464 0.19
1450 25 704 464 0.18 672 448 0.19
1350 25 704 464 0.17 656 432 0.19
1250 25 704 464 0.15 624 416 0.19
1200 25 704 464 0.15 608 400 0.20
1150 25 704 464 0.14 592 400 0.19
1100 25 704 464 0.13 592 384 0.19
1050 25 704 464 0.13 576 384 0.19
1000 25 704 464 0.12 560 368 0.19
950 25 704 464 0.12 544 368 0.19
900 25 704 464 0.11 528 352 0.19
850 25 704 464 0.10 512 336 0.20
800 25 704 464 0.10 496 336 0.19
750 25 704 464 0.09 480 320 0.20
700 25 704 464 0.09 464 304 0.20

[khp]

I strongly dislikes tables like this, it oversimplyfies the encoding process.

Someone might see this and this, and think this is all it takes to make perfect rips. Which would of course be very very wrong. All movies compress differently, depending on the amount of motion and noise in the video. If you wish to make an optimal choice of encoding resolution you should do a compressability test (GKnot comes in handy here).

Not to mention that each tabel only applies to one fixed aspect ration, and fps, taking all aspect ratios and fps speeds into account, you would need something like 10 different ables.

Besides the choice of resolution and bitrate, is only part of the equation for making a perfect rip. Tricks like cropping the edges and low quality encoding of the endcredits are equally important.

[UncasMS]

Tricks like cropping the edges and low quality encoding of the endcredits are equally important.

not to mention the influence of bframes, resizer or other filters

[frell]

thanks for the posts.

just because something can be misued, don't dislike it. people can misuse dvd archiving software, but don't dislike that software.

the "table" is worthless, but the excel spreadsheet calculation is nice. given a resolution, fps, and bitrate, it suggests to me what to resize to. otherwise i would be in the dark.

i always remove pre/post credits totally.
and of course, removing edges is a must.

and the gk process is too timeconsuming for me. i mean if i spend more than 1/2 hour backing up a dvd, then i might as well have just bought a 2nd copy. this is not a hobby for me. i use the clad dvd process which goes from a dvd to a frame served avi and a wav file in one step. in vdub and using it's job control, i go from these to a final avi in one last step. two steps. no demuxing/muxing etc.

frell