Welcome to Doom9's Forum, THE in-place to be for everyone interested in DVD conversion.

Before you start posting please read the forum rules. By posting to this forum you agree to abide by the rules.

 

Go Back   Doom9's Forum > Video Encoding > (Auto) Gordian Knot

Reply
 
Thread Tools Search this Thread Display Modes
Old 10th January 2002, 23:04   #1  |  Link
kermit23
Registered User
 
Join Date: Oct 2001
Posts: 3
16 bit vs. 24 bit

When I use GKnot 0.23beta to make a divx-movie, I get avi's with a 16-bit color depth. This looks very unusual to me, all my other divx movies have a 24-bit color depth. GKnot uses DivX 4.12 and Virtual Dub.
But there's another thing, when I close GKnot, load the avs-file in Virtual Dub and encode the movie with DivX 4.12, then I get a 24-bit color depth avi. This looks very strange to me, any suggestions?
kermit23 is offline   Reply With Quote
Old 11th January 2002, 01:01   #2  |  Link
TheWEF
Gordian Mod.
 
TheWEF's Avatar
 
Join Date: Oct 2001
Posts: 772

gknot sets vdub/nandub in "fast recompress" mode.
the video is not converted to rgb but stays in it's original yuv format.
for some reason explorer-file-properties show 16bit for yuv videos.

don't worry, quality is the same.

wef.
TheWEF is offline   Reply With Quote
Old 11th January 2002, 01:05   #3  |  Link
kermit23
Registered User
 
Join Date: Oct 2001
Posts: 3
If, as you say, quality is the same, does that mean that most DivX movies have a maximum color depth of 16 bits although its properties (right mouse click on avi, and then summary) says it has 24 bits color depth, because they've been converted to rgb first?
Or 16 bits is shown, but it is 24 bits?
kermit23 is offline   Reply With Quote
Old 11th January 2002, 01:53   #4  |  Link
TheWEF
Gordian Mod.
 
TheWEF's Avatar
 
Join Date: Oct 2001
Posts: 772

http://www.inforamp.net/~poynton/not.../ColorFAQ.html
TheWEF is offline   Reply With Quote
Old 12th January 2002, 13:50   #5  |  Link
Acaila
Retired
 
Acaila's Avatar
 
Join Date: Jan 2002
Location: Netherlands
Posts: 1,529
Quote:
If, as you say, quality is the same, does that mean that most DivX movies have a maximum color depth of 16 bits although its properties (right mouse click on avi, and then summary) says it has 24 bits color depth, because they've been converted to rgb first?
Or 16 bits is shown, but it is 24 bits?
Actual color depth is 24 bits, it's only shown as 16 bits.

Btw, VirtualDub uses the same information as explorer shows, so that a movie encoded in fast-recompress mode can't be joined to a movie encoded in full-processing mode. Unless you change the color depth with a hex editor.

Last edited by Acaila; 12th January 2002 at 13:54.
Acaila is offline   Reply With Quote
Old 15th January 2002, 20:00   #6  |  Link
LotharZ
Registered User
 
Join Date: Oct 2001
Posts: 47
As I can change the color depth with a hex editor???
LotharZ is offline   Reply With Quote
Old 15th January 2002, 20:58   #7  |  Link
Acaila
Retired
 
Acaila's Avatar
 
Join Date: Jan 2002
Location: Netherlands
Posts: 1,529
It's just a one-byte flag, byte number 187 in the avi.
This doesn't change the actual color depth of each frame, just the flag that is read by programs.

Actually I don't use a hex editor, but an editor that translates hex language into decimal language. It's much easier to search for a specific number, coz you don't have to translate it first before you search.

!Don't change it unless you really need it for something!
Acaila is offline   Reply With Quote
Old 16th January 2002, 09:58   #8  |  Link
rui
Registered User
 
Join Date: Dec 2001
Location: Portugal
Posts: 730
But when using divx3, Gnot displays 24 bits??

By The WEF:

"gknot sets vdub/nandub in "fast recompress" mode.
the video is not converted to rgb but stays in it's original yuv format.
for some reason explorer-file-properties show 16bit for yuv videos"

But, when i make a conversion using Gnot and divx3, the avi file allways has 24 bits. I am not asking because of the 16 bits/24 bits issue. I am asking if this means that Nandub isn't in fast recompress mode.
__________________
Rui
rui is offline   Reply With Quote
Old 16th January 2002, 13:36   #9  |  Link
kermit23
Registered User
 
Join Date: Oct 2001
Posts: 3
> Actual color depth is 24 bits, it's only shown as 16 bits.

But when I change my display settings to 16-bit color (instead of 24 or 32), I see no difference in a 16-bit (yuv) movie. So you might think it has only a 16 bit colordepth, because when I play another movie in 16 bits colordepth (for example a DivX, RGB 24 bits so it's encoded in full processing mode!!!), it looks crap (you can clearly see the difference between 16 and 24 bits).
kermit23 is offline   Reply With Quote
Old 17th January 2002, 01:17   #10  |  Link
TheWEF
Gordian Mod.
 
TheWEF's Avatar
 
Join Date: Oct 2001
Posts: 772
if you see a difference changing desktop color deph it only means that your hardware-overlay is not kicking in. -> gfx driver problem.

kermit, you can trust me: "16bit" does not mean less quality - period.

wef.
TheWEF is offline   Reply With Quote
Old 9th March 2002, 17:36   #11  |  Link
ThePanda
Registered User
 
Join Date: Oct 2001
Location: Connecticut
Posts: 117
If I set VirtualDub to encode at 16-bit instead of 24-bit, will I get much better compression since it needs to encode so many less colors? I figured it would be better for anime but I don't know. How many colors can the human eye tell apart? Maybe you notice the differences more if it's in a gradient or something..
ThePanda is offline   Reply With Quote
Old 19th March 2003, 16:29   #12  |  Link
Belgabor
VDubMod Devel
 
Belgabor's Avatar
 
Join Date: Oct 2001
Location: Germany
Posts: 826
To my knowledge all MPEG4 codecs use YV12 color format internally, which makes the true value 12 bit, regardless what windoze chooses to report. (That's why it shouldn't matter at all if you process at '16 bpp' or '24 bpp' for compressibility)
16 bit RGB can be easily noticed on gradients, but 12bit YV12 or 16bit YUY2 are completely diffrent things, since these values are the middle bits/pixel over the entire video, if you look at a single pixel its 24 bit(*), only two(YUY2) or four(YV12) adjacent pixels share the same values in the chroma planes.

(*) This is not completely true since valid streams may not have the full value range per channel (e.g. iirc 16-235 for luma).
__________________
VirtualDubMod [SourceForge : Tracker/DL] (FAQ, Some rules)
Be sure to also download the latest DLL package or get the all inclusive package!
Before you post questions, please read the VirtualDub and/or VirtualDubMod FAQ.
If you have a bug report or feature request for VirtualDubMod, be sure to read the rules first.
We give 100% of your donations to the Open Source community

Last edited by Belgabor; 19th March 2003 at 16:32.
Belgabor is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT +1. The time now is 20:25.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.