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Questions regarding the SAA7105 / SAA7108 / SAA7109 encoder

Discussion in 'Embedded' started by benjamin.couillard, Jul 21, 2008.

  1. 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.couillard, Jul 21, 2008
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  2. >,
    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

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    Paul Carpenter, Jul 22, 2008
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