Hi,
I am developing an AVStream mini driver for an USB analog TV device. I have implemented the related codes of the VBI pin of the capture filter. Although my driver can output raw VBI data, but CC decoder filter can’t decode them. I also used the VBI scope to see the VBI waveform. But I can’t see what’s wrang with the raw VBI data stream.
Does anybody know where can I get a working sample code of the AVStream VBI driver? There is a working stream class video capture driver sample, testcap. But I want an AVStream one.
George
Hi George:
When you look at the VBIScope waveform are there any zero values in the VBI
stream. This will show
up as a sharp drop in the waveform for one bit time. I worked on a capture
board where we had to search
the VBI data and strip out the zero byte samples. This was a problem /
behavior of the video decoder chips
slicer we were using. Sorry I don’t remember the exact chip part number.
Do the values for line number, fields, Bpl, Str, NTSC and the waveform -
should have some cycles that match
the timing shown in the MCPCvidcap.doc?
Phil
Phil,
I used a sample VBI stream data instead of real VBI stream from my video decoder chip. I got the VBI streeam data pattern from other working analog TV device that can show VBI closed caption data. I dump their raw VBI data from the capture filter VBI pin first, and feed these VBI stream pattern to my driver’s capture filter VBI pin. My driver can output the same VBI data stream with the testing pattern. I also can see the same VBI waveform from the VBIScope.
I think I suffer a awkward problem. I had referenced some driver sample to implement my VBI closed caption function. But from the limited DDK documentation and samples, I can’t come out a working solution in a short run.
George