question about xvid single pass quantizer=1, and 2 pass encode at same bittrate

[nukesgoboom]

i encoded a uncompressed file with xvid with single pass quantizer=1. i played the file in MPC and the bittrate was around 20,000 kbps

if i had done 2 pass encoding, and then set the bittrate at 20,000 kbps would the result look better or the same than single pass quanztizer=1? am i correct to assume that single pass quant 1 is the highest quality xvid can create?

thanks for your time.

[GodofaGap]

am i correct to assume that single pass quant 1 is the highest quality xvid can create?
Yes, you are correct.

[Sharktooth]

quant 1 is the highest quality xvid can create... but you can get different results with different quantization matrices.

[foxyshadis]

q1 is generally nearly as large as lossless (or larger if using specialized custom matrices), consider simply storing/distributing your files in huffyuv if you have that much space to play with.

[Prettz]

i encoded a uncompressed file with xvid with single pass quantizer=1. i played the file in MPC and the bittrate was around 20,000 kbps

Holy crap! That's 20Mbps, more than 2 times higher than DVD bitrate! Why would you do this? What was the source video of?

[henryho_hk]

Does XviD make different B-frame decisions in 1-pass and 2-pass modes?

[Didée]

Does XviD make different B-frame decisions in 1-pass and 2-pass modes?
In 2nd pass, XviD does not make any B-frame decisions at all. Frametype decisions are made during 1st pass, and written to the stats file. 2nd-pass will just use the frametypes it finds in the stats file.

One more reason for not making a too fast first pass, BTW.

[nukesgoboom]

i was capturing 640x480 30 fps uncompressed data from my xbox using s-video input with a capture card on my computer, with a program called dscaler. the original bittrate was around 27,000 kbps. after xvid encoding single pass quant=1 it was around 20,000 kbps.

from now on i will simply use huffyuv to store video, since xvid at quant=1 produces the same filesize.


however, if xvid were ever to have a lossless feature, would it offer lower filesize than huffyuv, or at least a quicker decoding speed? huffyuv requires some serious power for decoding... however encoding with huffyuv is much easier.

also, is it possible to have a lossless mode but NOT have every frame be a keyframe? i wonder...

[foxyshadis]

Huffyuv is about 5x faster than xvid, both ways; the original huffyuv and the lavc/ffdshow version should be around 1.5x as fast decoding as encoding. Something's goofy if it's much slower.

Some lossless encoders with delta frames: FFV1, x264, MSU, MSU Screen. The first three are very slow and only 20-30% smaller than huffyuv though. (Screen is only useful for old games and screen captures.)

[Didée]

+ on the decoding side, Huffyuv gets lighter if the "predict" mode for encoding was set to "left" or "plane". "median" is the slowest of all, but compresses a little bit more than the other two.