[linux-dvb] Re: problems with dvb-kernel

[Michael Hunold <hunold@convergence.de>]

Hello Guido,

> > However - kvdr can not display Xv with it (just overlay works), just a 
> > green screen so i can not verify if the flashes are gone at least.
Unfortunately, "kvdr" won't run with "dvb-kernel" without major changes. 
The "problem" is, that the capture subsystem has been changed 
fundamentaly between Video4Linux-1 and Video4Linux-2.

These are the main problems when running "kvdr" through the 
compatibility layer:

1) You use VIDEO_PALETTE_YUV422 for capturing. Due to a hardware bug 
this byteorder is not supported by the saa7146 in hardware. In the old 
av7110 driver, the frames are captured in VIDEO_PALETTE_UYVY, then the 
bytes are swapped in software. Ieeek! The new Video4Linux-2 driver has 
"support" for this byteorder removed. This leads to "capture format not 
supported" error messages on the syslog. If you change this in the kvdr 
code, capturing will work, but the picture will be greenish/purple, due 
to the swapped U and V components.

2) With V4L-1, capturing was set frame size and format, SYNC frame, 
CAPTURE frame. V4L-2 however requires request_buffers(), 
query_buffers(), stream_on(), queuebuffer(), dequeuebuffer() and 
stream_off(). This semantic cannot be mapped adequately.
So if you resize the window, you'll get "setting format not allowed 
during streaming capture" error messages.

I've send to you a small V4L-2 capture application in private, that 
shows the use of the V4L-2 capture subsystem. IMHO it would be best, if 
you write a separate V4L-2 capture core for "kvdr".

CU
Michael.



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