How to capture screen with RGB?

[VHDBBTX]

I try to use x264 to capture but video color is very pale when compare with screen.
One way as I know is I must capture by using lossless codec with RGB color space but file size is very huge and if I convert to x264 it's have a problem with picture on video and x264 not support RGB as same.

Question is can I capture my screen with x264 in RGB or anyway to solve my problem.

Sory, I'm not strong in English.
Thank you.

[jagabo]

AviSynth script for standard definition (720x576 or less):

AviSource("RGB.AVI")
ConvertToYV12()

AviSynth script for high definition (greater than 720x576):

AviSource("RGB.AVI")
ConvertToYV12(matrix="rec709")

Encode that with x264.

Also, how are you comparing your RGB and x264 encodes? Viewing both on the screen at the same time in two media players? If so, you may just be seeing the difference in processing amp between video overlay and non video overlay display. Open them in the opposite order and you may see the opposite results.

[VHDBBTX]

I mean I want to use RGB on x264 codec. I try to config decoder by force using RGB color space but the result is same color is very pale. How I compare, I compare by open video near position where I capture, the difference is very clear.

[jagabo]

x264 only works in YV12 (like all MPEG family encoders). It has no ability to encode as RGB. You need to convert your RGB to YV12 correctly in order to get correct colors on playback. I gave you AviSynth script to do that.

[VHDBBTX]

Hmm. I get it now. Sory as you know I'm not strong in Engslish. Thank you.

[themaster1]

x264 only works in YV12

It also work in YUY2 according to my experience

[poisondeathray]

x264 only works in YV12

It also work in YUY2 according to my experience

Not yet, currently it's only YV12 4:2:0 .

But the developers are are working on 4:2:2 , 4:4:4 and 10-bit support ...eventually. It's on the to-do list for the Google Summer of Code for 2010 , as are a few other projects
http://wiki.videolan.org/SoC_x264_2010

[VHDBBTX]

Hmm. I was tested play by using script YV12, It's little better but still too much pale. What I can do? - - For example I capture video on youtube* what color space of that video stream, I think it's not RGB but why I capture it a video is very pale when compare it. *(I know it can download)

[jagabo]

You probably have a playback problem, not an encoding problem. Post a short sample of your source and your x264 output.

[VHDBBTX]

ConvertToYV12() - Use this script to play.
Player - MPC
Filter - AVI Decompressor (YV12)
left - desktop
right - video

You will see gray line at top and bottom on left which is original but video became orange.
This image is exactly as I see when play.


[Attachment 1667 - Click to enlarge]

[jagabo]

Your attachment didn't work.

[VHDBBTX]

- - What do you mean? It's clear. Why?

[poisondeathray]

We can't see anything , the screenshot or file, or whatever you uploaded didn't work

[VHDBBTX]

http://img682.imageshack.us/img682/4930/37110095.png Gray line on top and border on bottom. Can I encode for clear orange area like left picture which original picture. Right picture is very rough*. *I don't know what it this for call.

[jagabo]

What you are seeing is normal when converting RGB to YV12. YV12 encodes colors at half the resolution (both axis) so sharp colored edges or other small colored details get blurred. All MPEG family encoders work in YV12 internally (actually some MPEG 2 encoders have a YUY2 mode). More examples:

https://forum.videohelp.com/threads/294144-Viewing-tests-and-sample-files?p=1792760&vie...=1#post1792760

[VHDBBTX]

Hmm... Thank you so much.

One more, if I will capture video from screen like youtube* which have real resolution 200 x 200, between capture with real resolution 200x200 and 200% zoom than capture, what should I do for best quality and detail, I think zoom than capture may be good for sure to capture much more detail. Am I right?

*I know it can download, just for example.

[edDV]

Are you accepting of >double file sizes for 4:4:4 RGB vs. YV12 at similar compression?

The main reason for ITU-Rec 601/709 was to reduce bit rate* to less than half with very little picture quality loss as tested by human perception.

4:4:4 RGB or YCbCr makes an excellent production format but is wasteful for distribution.



* ITU-Rec 601/709 allow for 4:4:4 as a production intermediate format.

[VHDBBTX]

Thank you.

Am I accept? Yes I accept double size, because in half of my work must use RGB only.
YV12 is great and little picture quality loss I know that and half of my work used this but half more I want to use RGB too.

About human perception test, I think it's like lossy and lossless sound, you may be not hear the difference on few times but if you listen carefully or listen often enough you will hear a very difference of that which I found with myself.

[jagabo]

Videos from Youtube (or any other streaming source) will be encoded as YV12 before it gets to you so there is no advantage to capturing at double the frame size. All high compression codecs use YV12.

[VHDBBTX]

Hmm... Thank you.

Last one if I capture with x264 lossless than I want to compress to lower size what should I do. I should uncompress before encode or not neccessary to uncompress and what difference of fourcc x264 X264 h264 H264 avc1 AVC1 I very confuse with character case, x264=X264?

What benefit of
x264 =?
X264 =?
H264 =?
VSSH =?

[poisondeathray]

no difference between the fourcc's they mean the same thing, avc video (mpeg4 part10)

x264 is an encoder, and open source encoding implementation of avc

You don't need to uncompress before encoding, the decoder that you use will do that automatically. As it decodes, it passes uncompressed frames to whatever encoder you use.

I don't see any benefit in capturing x264 lossless if you are going to be re-encoding anyway to x264 with different settings (ie. if your computer is fast enough, I would just use the final format settings) - unless you are going to be doing multiple different format encodes

If you capture an RGB source with x264 lossless , it will be YV12 ; obviously there is quality loss there. (Although the youtube source is YV12, it's converted to RGB for your flash display - and there is quality loss in that stage, and again if you convert RGB=>YV12 again ; that's why it's better to just download the video)

[jagabo]

Youtube should be "captured" by downloading the files, not by screen capture.

[themaster1]

For Christ sake, download the video through this site!: http://keepvid.com/

"ScreenCap a youtube video"..i read it all in here

[VHDBBTX]

Sory not last post anymore. ^^ Sory for my newbie in video coding.

If avi doesn't support that features then my encoded avi have contained that features?
I use x264vfw and output file is avi, I heard avi not support few features like multiple reference frames, So my avi have that features? When I play it that features will working? Or I must have to convert to mp4 to use that features? I little confuse about x264vfw, if it not support that features why it have an options to set.

I find the way to set output to mp4 but I don't see anywhere.

Thank you.

[poisondeathray]

Newer versions x264vfw can output .mp4 container, .mkv and rawavc , and it also makes a dummy avi. You need to use the command line box

you can download these beta builds from here
http://komisar.gin.by/

read this thread, starting from page 29
http://forum.doom9.org/showthread.php?t=98247&page=29


The vfw version still lacks some of the features of the CLI version, and seems to be quite a bit slower during encoding. That thread lists some of the missing features

AVI container does support multiple reference frames, but the issues is b-frames which can cause playback issues in some players (AVI container is 1 frame in, 1 frame out, so bidirectional and b-pyramid can cause issues). I suspect this is also one of the reasons it seems to be slower during encoding

[VHDBBTX]

First which I want to know is if I encode to avi with x264vfw that feature contain in my avi?, because I use mediainfo to detect my avi and it have all of features.

If I convert to .mp4 my avi will loss quality?

Thank you.

[poisondeathray]

If you re-wrap the container (i.e. just switch containers) , there will be no loss

If you re-encode with a lossy format, there will be loss

You could re-wrap with mp4box (yamb) for example

[VHDBBTX]

Please, I want to know if I encode to avi with x264vfw feature of h264 will contain in my avi?, because I use mediainfo to detect my avi and it have all of features.

[poisondeathray]

Most of the features are supported in the newer builds. The exceptions are listed in that thread I linked above

[VHDBBTX]

Hmm... Sory for my English. I mean if I encode by using x264vfw to avi container then I re-wrap to mp4, I will have all features same direct output to mp4?