Allow separate chroma output from ld-chroma-encoder #777
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atsampson
added
enhancement
ld-decode-tools
ifb spotted, while working on the NTSC encoder, that this filter didn't quite meet the spec in Clarke -- it had slightly less than 20 dB attenuation at 4 MHz. Recompute it so it now has slightly more. Also correct the misleading comment -- the filter isn't taken from pyctools-pal. Comparing the results from check-chroma-pal, this results in ~0.02 dB lower PSNR on colourbars.
There's no need for QVector's COW behaviour here.
This matches the output from vhs-decode, which ld-analyse already accepts.
happycube
approved these changes
Aug 22, 2022
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The main aim here was to make it possible for ld-chroma-encoder to produce the same kind of output as vhs-decode, with chroma in one file and luma + syncs in another. Besides testing the handling of this in other tools, this is useful for tuning ld-chroma-decoder, because you can feed video through it and see exactly which parts of the composite signal are chroma. I plan to use this for calibrating the Transform PAL thresholds.
Some other improvements to ld-chroma-encoder included: