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Delphi - how do I code for RGB to YUV - (bmp or stream) ??
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vhelp
..Semi Neutral..


Joined: 31 Mar 2001
Location: New York
Post Posted: Apr 19, 2005 23:24 Posts Comp View users profile Send private message Reply with quote
-- vLAB 001 - bitmap data to YUV file (stream or other) --

Looking for some simple Delphi code to convert my RGB bitmap
to a YUV bitmap. That is, I know how to convert the RGB to YUV.
But, I'm not sure of the layout of the bitmap, to lay out the
YUV. I realize that it's probably a STREAM that I need to create,
(ie, bitmap.yuv) for instance.
.
I want to convert to YUV, save it. Then, read it in again, back
into RGB.

For intance, if I have a 5x5 RGB pixel bitmap, and I want to convert
it to YUV, the storage format (Row x Col) is:

Code:

      1         2         3         4         5
1 [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V]
2 [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V]
3 [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V]
4 [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V]
5 [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V] [Y][U][V]


The numbers (1 through 5) are the pixel places, and I think that
the YUV is one pixel - though I'm confused rolleyes.gif

Any help would be greatly aprecated. Thanks.

Cheers,
-vhelp 3274

Last edited by vhelp on Apr 23, 2005 10:10, edited 2 times in total
borax
Member


Joined: 20 Apr 2004
Location: Germany
Post Posted: Apr 23, 2005 03:11 Posts Comp View users profile Send private message Reply with quote
I don't know it either, but you can use avisynth + imagereader/imagewriter with a very small bitmap (like your 5*5) and have a look to the layout in the saved bitmap (can be saved as yuv!)
_________________
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http://www.videohelp.com/~gfd/

vhelp
..Semi Neutral..


Joined: 31 Mar 2001
Location: New York
Post Posted: Apr 23, 2005 10:02 Posts Comp View users profile Send private message Reply with quote
Quote:
..(can be saved as yuv!)


But it wouldn't be the same rolleyes.gif

I would like to make a standard YUV format file. (be it bitmap or stream)
whatever format/structure they usually are made in. Its all very confusing
to me at the moment. I think all I need to *see* the picture is the
actual layout of the numbers/pixels.

I do have a few samples (why I didn't think of it in the first place)
but I don't think they are standard format in structure. They are all
based on a STREAM. YV12; YVU9; and 411 and something else I think (from
one of those Borland or efg sites, I think)

I could "re-create the wheel" by making my *own* format (stream or something)
(I was thinking of this) but if others want to open the YUV file w/ standard
or commercial tools of there preference, then my home-brew will not open or
convert properly them.. not that I'll be distributing any, but you never know
who might want to D/L such files for there own purposes/studies. And, I'd like
for it to be accurate for there own tools and studying smile.gif

Below is an example of a format I was working on.
( maybe I'll start my own LABS tongue.gif )

Given my 5x5 bitmap layout (above post) but we'll use a 2x4 (2 col, 4 row)
for space purposes. I was hoping to duplicate it, but I'm still confused.
I'm not sure if this is a Planar or Packed format.

411 FORMAT

[Y][Y][Y][Y]
[Cb][Cr]

or

[Y][Y][Y][Y]
[Cr][Cb]

or

[Y][Y][Y][Y]
[U][V]

or, if in a file, the sequence ? would be similar like this..

Code:

        - 1 -               - 2 -
1 - [Y][Y][Y][Y].[U][V] [Y][Y][Y][Y].[U][V]
2 - [Y][Y][Y][Y].[U][V] [Y][Y][Y][Y].[U][V]
3 - [Y][Y][Y][Y].[U][V] [Y][Y][Y][Y].[U][V]
4 - [Y][Y][Y][Y].[U][V] [Y][Y][Y][Y].[U][V]


.. I realize, that I can take a rgb bitmap and convert (pix by pix) the r.g.b
.. to YUV and store it in any kind of file container I design (but don't forget
.. the note above, why I don't want to go that way, unless I have to)

RGB pixel layout:

Code:

     -1-  -2-
1 - [RGB][RGB]
2 - [RGB][RGB]
3 - [RGB][RGB]
4 - [RGB][RGB]


So, given the the following color information conversion for our first pixel:

R=255; G=255; B=255

Y = (R255*.3)+(G255*.6)+(B255*.1) = 255
U = ( 0.493 * (B - Y) )
V = ( 0.877 * (R - Y) )

So, Y=255; U=0; V=0; Thus, our first set of YUV data layout, as observed
over the "underline" (if I understood the process correctly, and using the
planar_or_packed format) would be:

Code:

[255][Y][Y][Y].[0][0] [Y][Y][Y][Y].[U][V]
---------------------


I'm still confused, and I think I have things messed up in the above
layout. If I learn anything new, I'll revise and bring to light.

Comments, anyone ??

-vhelp 3284
EDITED - Sat - 11:59pm

Last edited by vhelp on Apr 23, 2005 23:01, edited 1 time in total
borax
Member


Joined: 20 Apr 2004
Location: Germany
Post Posted: Apr 23, 2005 16:52 Posts Comp View users profile Send private message Reply with quote
I'm not sure if there is anything like a real standard for YUV bitmap data. Even for Streams (where this format is at least 'common') there are several "standards" (as you have mentioned already): YUV 4:4:4, YUV 4:2:2, YUV 4:1:1.
I think to have the best conversion, use should use YUV 4:4:4

There are also some (commercial) graphic conversion programs that support YUV data. This could also be seen as 'standard':
http://64.233.183.104/search?q=cache:w-et91QGY2sJ:www.pcsupport.d ... &hl=de
_________________
GUI for dvdauthor:
http://www.videohelp.com/~gfd/

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