Order of RGB or YUV Frame values in memory

Inc · 16th August 2005, 12:31

Question a):

Lets assume I do load rgb data into memory using dgdecode.dll's getRGBFrame() at a memorypointer *rgb24.

Now how is the order of the RGB data in memory:

(RGB24 Like ...

RGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGB ...... etc.

I do know getRGBFrame results in rgb24 data, but just to know how generally rgb32 data is stored )

RGB32 like ...

RGBARGBARGBARGBARGBARGBARGBARGBARGBA ..... etc.

And for YUV via dgdecode.dll's getFrame()

YUVYUVYUVYUVYUVYUVYUVYUVYUVYUVYUVYUV .... etc.

is that right? I think not due 4:2:0 12 Bit allocation?

Question b)

If I do use the VFW API AviFileGetFrame() is there generally a RGB result, no matter if even the Frame in the avi is YUV ?

Would the allocation of Pixeldata using AviFileGetFrame() also be stored as YUV Values in Memory like ...

B = BITMAPINFOHEADER data and its size

BYUVBYUVBYUVBYUVBYUVBYUV .... etc.

?

Thanks for your help

Purpose of all this is that I want to build an autocrop part in a video applikation using the way of directly peeking the memory instead of GetPixe() via API out of a generated Bitmap using SetDIBits() ... I think the peek() approach would be much faster.

Also if I can handle it, I would like to build a histogram window using the peek function on the image data at a given Memorypointer.

Wilbert · 16th August 2005, 17:25

Regarding question a:

Quote:

(RGB24 Like ...

RGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGB ...... etc.

It is

BGR BGR ...

Quote:

RGB32 like ...

RGBARGBARGBARGBARGBARGBARGBARGBARGBA ..... etc.

Likewise

BGRA BGRA ...

Quote:

And for YUV via dgdecode.dll's getFrame()

YUVYUVYUVYUVYUVYUVYUVYUVYUVYUVYUVYUV .... etc.

is that right? I think not due 4:2:0 12 Bit allocation?

For YV12 planar: first Y plane, then V plane, then U plane. I guess you know YUY2 (YUYV YUYV ...).

Inc · 17th August 2005, 12:47

Ah, yep RGB is ordered as BGR, now I remember, thanks.

But about YV12 and YUY2 ...

Did I understood right that YV12 is ordered as YVUYVUYVUYVUYVUYVU .... ?
But how about peeking these Y V U values in the memory?

I do peek the B,G,R each as Byte including 8bits, but I dont think Y,V,U will be byte,byte,byte ?

Also how are the rows of the image allocated?
Means in case of a 10px width and 4px height image ...

is it a zigzag order? :

00 01 02 03 04 05 06 07 08 09
10 11 12 13 14 15 16 17 18 19
20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35 36 37 38 39

(above assuming one Number would contain RGB just for demonstration)

Nic · 17th August 2005, 19:17

No, YV12 is planar....i.e. YYYYYYYYUUVV So all the Ys then the Us then the Vs.

-Nic

16th August 2005, 12:31	#1 \| Link
Inc Squeeze it! Join Date: Oct 2003 Location: Germany Posts: 472	Order of RGB or YUV Frame values in memory Question a): Lets assume I do load rgb data into memory using dgdecode.dll's getRGBFrame() at a memorypointer rgb24. Now how is the order of the RGB data in memory: (RGB24 Like ... RGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGBRGB ...... etc. I do know getRGBFrame results in rgb24 data, but just to know how generally rgb32 data is stored ) RGB32 like ... RGBARGBARGBARGBARGBARGBARGBARGBARGBA ..... etc. And for YUV via dgdecode.dll's getFrame() YUVYUVYUVYUVYUVYUVYUVYUVYUVYUVYUVYUV .... etc. is that right? I think not due 4:2:0 12 Bit allocation? Question b)* If I do use the VFW API AviFileGetFrame() is there generally a RGB result, no matter if even the Frame in the avi is YUV ? Would the allocation of Pixeldata using AviFileGetFrame() also be stored as YUV Values in Memory like ... B = BITMAPINFOHEADER data and its size BYUVBYUVBYUVBYUVBYUVBYUV .... etc. ? Thanks for your help Purpose of all this is that I want to build an autocrop part in a video applikation using the way of directly peeking the memory instead of GetPixe() via API out of a generated Bitmap using SetDIBits() ... I think the peek() approach would be much faster. Also if I can handle it, I would like to build a histogram window using the peek function on the image data at a given Memorypointer. Last edited by Inc; 16th August 2005 at 12:35.

17th August 2005, 12:47	#3 \| Link
Inc Squeeze it! Join Date: Oct 2003 Location: Germany Posts: 472	Ah, yep RGB is ordered as BGR, now I remember, thanks. But about YV12 and YUY2 ... Did I understood right that YV12 is ordered as YVUYVUYVUYVUYVUYVU .... ? But how about peeking these Y V U values in the memory? I do peek the B,G,R each as Byte including 8bits, but I dont think Y,V,U will be byte,byte,byte ? Also how are the rows of the image allocated? Means in case of a 10px width and 4px height image ... is it a zigzag order? : 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 (above assuming one Number would contain RGB just for demonstration)

17th August 2005, 19:17	#4 \| Link
Nic Moderator Join Date: Oct 2001 Location: England Posts: 3,285	No, YV12 is planar....i.e. YYYYYYYYUUVV So all the Ys then the Us then the Vs. -Nic