TVP5150 & field inversion problem

however, when I change the video standard from NTSC to PAL & vice a versa, the field inversion problem occurs. Any pointer to solve this problem?

[manju] I think you should make sure to stop streaming and restart (and also doing QUERY_STD) when you change from NTSC to PAL and vice-versa. There  is no auto detection for input disconnection on Dm6446 so it will not know that you switched standards.

I have another question. If no video source is connected to TVP5150, the tvp5150 should produce black frames. How can this be achieved? need to set any register for this?

[manju] If there is no input, there would be no interrupts and there is a possibility that you applications might seem to be hung. frames cannot be produced in the interim.

Manisha,

There are 2 parts to this issue.

First, the TVP5150 can be configured to automatically switch its output format to track the input format (called auto switch). This will not automatically cause the processor to automatically switch its input format.

Second, if the format changes it will still be necessary to re-configure the processor input even if the TVP is configured for auto-switch.

Regarding the no-input generation, there is a register setting which will ensure that the output data stream always conforms to a standard active frame format even when no analog input is presented. This is necessary to ensure that the processor always receives a correctly sized active region.

What I think you really need to do here is disable auto-switch and use the TVP5150 auto detect instead. If you use auto-switch then there will be a period where, for example, the TVP51510 can switch from say NTSC to PAL but the processor is still configured to NTSC.

If you use auto-detect instead then you can use either polling or an interrupt from the TVP5150 for format switching. Then you could shut down the processor input, switch the TVP5150 format, re-configure the processor input then re-enable. This will ensure that there are no miss-matched frames.

BR,

Steve

Hello Manisha,

Can you give us the version of the TVP5150 you are using?  There are 3 version of them.  If you are using the latest which is 4.00, can you use our latest patch v048CAA?  it can be download from:

http://dleinspect.itg.ti.com:82/dsps/dsps_public_sw/dsps_swops_houston/ANALOG_VIDEO/Analog_Video_Decoder_Versions.htm

Regards,

Viet

Hi,

Thanks for the information.  I have enabled auto switch by setting 00h in the register 0/40 (28h).  It would be helpful if you could tell how to enable auto detect in TVP5150. 

Also, please let me know which register should be set to handle no-input generation situation.

Thanks  & regards,

manisha