Video sample rate settings?

[rick63366]

Hello folks, I'm a beginning encoder and I want to put all my home video on Xvid so I can watch it on my standalone player. With my old standalone (Philips dvp642) I could play 12-bit sampled Xvid files (home made with AutoGK) 16-bit files (home-made with Ultra avi converter) but when I dl'd an Xvid file over the net that was 24-bit it balked, so I got to wondering what determines the video sample rate? (I have since replaced the player with an RCA DRC240N that not only played the 24-bit file, but also played a 3ivx file!)
I didn't see any particular settings in either application that would allow me to change it. Is that just a result of say, less compression (like compressing a two hour movie to 1400MB instead of 700MB) or of a particular quality setting that I can manipulate? I like AutoGK but I assume that a higher video sample rate translates to higher quality at lower file sizes and would like to be able to encode my own stuff at the best quality/size compromise point (am I mistaken about this?). I also don't like to encode on the fly from my capture card (sony handycam with rca/s-video hookups to a Leadtek Winfast 2000 Dlx) because I think that I would get better quality if I capture as a high bit-rate mpeg2, then use AutoGK to convert it to Xvid at preset 1 or 2-cd settings. The Ultra avi converter is pretty fast but I have to use standard Xvid settings and I can't seem to get the filesizes/quality to come out like I want compared to AutoGK (It' a little over my head right now, so AutoGK is easiest for me to use--laugh and groan if you must)
Can you help? Any positive feedback would be much appreciated, and as I gain experience perhaps I can help others with similar problems. Thanks for taking the time to read this.

(I put this in Xvid forum because I'm using Xvid codec, and I don't want to double post in the AutoGK forums for what may be an Xvid solution.)

rick

[stephanV]

XviD always uses YV12 as native colorspace and you cannot change that

so while the colodepth is 24 bit, the average bits per pixel is 12 bit.

[rick63366]

XviD always uses YV12 as native colorspace and you cannot change that. So while the colordepth is 24 bit, the average bits per pixel is 12 bit.
Thanks for the reply. Please pardon my ignorance, but aren't other apps also using the Xvid codec and creating 16-bit and 24-bit files? I have 3 seperate sample rates on three separate Xvid-named files. Also, the file I encoded using Ultra avi converter was made with the Xvid config at 2-pass 2nd pass and a target bitrate of 2250kbs w/ 320kbsmp3 and it is labeled as a 16-bit file, and I have a 24-bit file mentioned earlier, so how can you say the xvid codec always uses 12-bit? I could maybe understand if it was AutoGK that only converts to 12-bit Xvid, but I have Xvid files with varying Video sample rates (12,16,24-bit).
Sorry for my misunderstanding of the basics...

[stephanV]

where do you get the info from? the internal colorspace of XviD is YV12. it is demanded by the MPEG4 specs. the value might refer to the colorspace that was fed into it or that the decoder outputs, but internally it is YV12.

BTW - a more correct term would be bit depth, not sampling rate :)

[rick63366]

Here is a screenshot of the file properties tabs. The smaller file (16-bit) was encoded with Ultra-avi Converter using the Xvid config settings on the left. The larger file was dl'd over the internet and is 24-bit Xvid. Every file I have ever encoded with Auto GK is 12-bit. That is why I was wondering about why there is a difference and wheteher I could manually select 16- or 24-bit vid sample encoding. Thanks again for your interest.

http://webpages.charter.net/rick63366/Xvidfilesproperties.jpg

[Dhampir]

If done properly, XviD should always show up as 12-bits, as like stephan has told you over and over, that it uses the YV12 colorspace which only has a 12-bit color depth. Something funky is being done during the encoding (possibly an intermediate colorspace conversion?) if it is showing it as 16 or 24 bit.

[stephanV]

the video sample size info has no meaning whatsoever :)

its not something you can set in XviD, i think it refers to the input colordepth... ill try a few short things to investigate.

[edit]it seems it indeed refers to the input colordepth :)

[Dhampir]

Originally posted by stephanV
[edit]it seems it indeed refers to the input colordepth :)

So then apparently whatever is being encoded was converted to some other colorspace before being encoded to XviD (possibly someone using full processing mode in Vdub)?

[stephanV]

probably yeah, although VDub in fast recompress mode also produces 16 bit... but it does that for both yv12 and RGB24

so for fast recompress the value is unreliable, but 24 bit would indeed appear to be the use of RGB24...

but the point of the value seems kinda missing if you ask me.

[rick63366]

stephanV, thanks for your replies and your patience. As shown on the screenshot, I wasn't lying, they are indeed listed at different values, hence my confusion. Whatever process Ultra-aviConverter uses creates the 16-bit designation regularly so it must use a different process than AutoGK or something. Maybe they should have named the description "colorspace" instead of "video sample size" in the properties tab if that is what it is based on. sheesh. Anyway, I really do appreciate you tracking that down for me. And since you think its not going to matter anyway then I won't bother with it anymore.

[unmei]

uh, "12bit" sound so wrong ..there are no 12bit samples anywhere in YV12, it's all 8-bit samples in all channels, only the chroma resolution is lower ><