2009-09-15 17:44:02     ADV7183A support through V4L - what does it mean?

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2009-09-15 17:44:02     ADV7183A support through V4L - what does it mean?

Owen OH (IRELAND)

Message: 79961   

 

Hello,

 

I'm just about to get started on a project to capture a PAL TV stream to an embedded system for (near) real time analysis to detect commercails/ adverts. I'm looking at using a BF533 STAMP board & and building an ADV7183A daughter board from the schematics in the hardware section of this site.

 

I understand that the ADV7183A chip is supported in the linux kernel through V4L but don't know what this means. Is it full support of the chips capabilities or in some way limited? V4L seems to be aimed towards webcams so I'm wondering if it can handle a PAL TV stream?

 

Many thanks,

 

Owen

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2009-09-15 17:50:49     Re: ADV7183A support through V4L - what does it mean?

Mike Frysinger (UNITED STATES)

Message: 79962   

 

V4L isnt limited by the format nor size nor interface

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2009-09-16 02:54:16     Re: ADV7183A support through V4L - what does it mean?

Jean-Christian de Rivaz (SWITZERLAND)

Message: 79969   

 

Hello,

 

If I remember correctly, the ADV7183A have to be initialised with a different set of parameters than with the ADV7183B. This should be doable, the parameters are listed into the datasheet.

 

V4L (and V4L2) is the general API for video capture on Linux. It provids an abstraction that let  (well written) applications get image stream, regardeless from the hardware that actually grab the images. So you can test you application on a Linux PC with a webcam and it should work the same on the embedded board after cross-compiling.

 

Now, the actual ADV7183B V4L backend is a minimal one. It just set the chip at his default settings and let the Blackfin V4L code grab images from it.

 

Jean-Christian de Rivaz

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2009-09-17 12:44:55     Re: ADV7183A support through V4L - what does it mean?

Owen OH (IRELAND)

Message: 80085   

 

Ok, thanks for the information.

 

Am I correct in saying that I don't need to write the driver code for this ADV7183A chip if I use the V4L?

 

I see the ADV7183A is outdated & design are recommended (by Analog) to use ADV7184 chips instead so I'm wondering will I need to do a heavy rewrite of the ADV7183A code?

 

Owen

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2009-09-17 14:29:12     Re: ADV7183A support through V4L - what does it mean?

Jean-Christian de Rivaz (SWITZERLAND)

Message: 80095   

 

You don't have to touche the ADV7183 code.

 

You have to write a new ADV7184 code. This should be relatively easy as you probably just need to replace the chip initialisation code after copying the ADV7183 code into a new file.

 

As for the init code of the new chip, the page 81 of the ADV7184 manual say:

 

"A register programming script consisting of I2C programming

examples for all standard modes supported by the ADV7184 is

available from the ADV7184 product page on the Analog Devices

website."

 

 

But I can't find those examples...

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