Questions regarding the SAA7105 / SAA7108 / SAA7109 encoder

Hi,

I'm currently using the SAA7108AE IC from NXP (Philips) for a video
decoding and encoding application. The decoding part works well so
there's no problem on this side. However, I have trouble making the
encoder work. The encoder part of the SAA7108AE is pretty much the
same as the SAA7105 (which is an encoder only).

Input to the encoder : ITU 656 stream (8 bits). 27 MHz clock

Output : NTSC

In the datasheet, they indicate how to take a progressive digital
video stream and convert it to an NTSC signal. Basically they give us
equations that are used to calculate the values that will be written
in the encoder registers.

However, they mention in the vertical scaler equations that these
equations are only valid for a non-interlaced input with an interlaced
output. But they don't specify what are the equations when using a
digital interlacted source for the input.

Does anyone here has any experience with that kind of application? I
emailed NXP for support, but so far I haven't got any answer from them

Best regards

Benjamin.

In article <6b2eaf2c-bfc8-45a6-9d2d-
cee33c6cf8c2@34g2000hsf.googlegroups.com>, benjamin.couillard@gmail.com 
says...
> Hi,
> 
> I'm currently using the SAA7108AE IC from NXP (Philips) for a video
> decoding and encoding application. The decoding part works well so
> there's no problem on this side. However, I have trouble making the
> encoder work. The encoder part of the SAA7108AE is pretty much the
> same as the SAA7105 (which is an encoder only).
> 
> Input to the encoder : ITU 656 stream (8 bits). 27 MHz clock
> 
> Output : NTSC
> 
> In the datasheet, they indicate how to take a progressive digital
> video stream and convert it to an NTSC signal. Basically they give us
> equations that are used to calculate the values that will be written
> in the encoder registers.
> 
> However, they mention in the vertical scaler equations that these
> equations are only valid for a non-interlaced input with an interlaced
> output. But they don't specify what are the equations when using a
> digital interlacted source for the input.
> 
> Does anyone here has any experience with that kind of application? I
> emailed NXP for support, but so far I haven't got any answer from them
 
Not that device but if you can understand what the equations are doing 
with the registers, you should be able to understand what little vertical
scaling  has to be done from ITU656 interlaced to NTSC interlaced.

It sounds to me that others designed the hardware and you are just doing
the software? If so the designer should have some idea what is to be 
acheived.


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