Reply To: Legacy AV In for OSSC Pro

[Zacabeb]

The dilemma is that the output from the ADV7280 that does decoding of composite and S-video in the Legacy AV Adapter is always rescaled internally in that IC to a 720 sample wide output.

Even if that’s then trimmed down to only the width of the actual graphics, for instance 640 samples, those will have to be either fit to a single pixel in the 1280×720 output or doubled to fill it. Either way the picture gets the wrong aspect ratio.

A solution to avoid the delay from Scaler mode would be to implement a horizontal-only polyphase scaling function also in A-LM mode so the picture can get scaled to an arbitrary width.

The challenge with that, I imagine, is getting the scaler IP core from Intel/Altera that’s used to accept reading from and writing to a small buffer of only a few lines rather than a full frame buffer as it does normally.