That sounds ideal for handling the low res sources. Is there any real downside to oversampling by 5x? I guess the tvp may run hotter and draw more power, although, it may actually be optimized for higher resolutions. Is it worth averaging (or median?) the samples rather than dropping them?
I looked into adding the hqx filter, but the implementations I’ve seen all generate a large lookup table to handle the RGB->YUV conversion and also perform some of the calculation. The tvp can output YUV, but I don’t think that helps. I wonder what happens to the filter if bits are dropped (or maybe hashed together) from the RGB value to make the lookup table a reasonable size.