{"id":511,"date":"2008-07-01T16:00:19","date_gmt":"2008-07-01T23:00:19","guid":{"rendered":"https:\/\/www.reenigne.org\/blog\/?p=511"},"modified":"2008-05-23T16:42:28","modified_gmt":"2008-05-23T23:42:28","slug":"ntsc-decoder","status":"publish","type":"post","link":"https:\/\/www.reenigne.org\/blog\/ntsc-decoder\/","title":{"rendered":"NTSC decoder"},"content":{"rendered":"

I want to write a piece of software that simulates a colour television (well, monitor really). It would really be a filter – the input is a sampled, quantized composite (CVBS) signal at some sample rate and the output is a series of video frames scaled to some resolution. I’d want the composite->RGB transformation to be done at the same time as the horizontal scaling to maximize quality whilst minimizing computation time. That means dynamically generating the appropriate filter kernel for a particular pixel width and sample rate.<\/p>\n

Such a thing would be particularly useful for emulating old computers and consoles which generated a composite colour signal directly (including the demo machine of yesterday’s post). In particular, it would render colour artifacts and interlacing perfectly). It would also be useful for simulating (for example) how an image would look on a TV for applications like DVD mastering.<\/p>\n

This is the kind of image it will be able to generate (this mock-up was done at fixed resolution and not in real time):<\/p>\n

\"\"<\/p>\n

No high-frequency chroma filtering was done on this image, so you can see the chroma artifacts. I wanted to include an animation showing the dot-crawl effects, but animated GIFs don’t go up to 60fps. It does look uncannily like a TV screen though.<\/p>\n

Writing this filter might even inspire me to fix up the NTSC emulation in MESS and improve the video emulation of machines like CGA, Apple II, CoCo and Atari 400\/800.<\/p>\n","protected":false},"excerpt":{"rendered":"

I want to write a piece of software that simulates a colour television (well, monitor really). It would really be a filter – the input is a sampled, quantized composite (CVBS) signal at some sample rate and the output is a series of video frames scaled to some resolution. I’d want the composite->RGB transformation to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[38,23],"tags":[],"class_list":["post-511","post","type-post","status-publish","format-standard","hentry","category-emulation","category-video"],"_links":{"self":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/511","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/comments?post=511"}],"version-history":[{"count":0,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/posts\/511\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/media?parent=511"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/categories?post=511"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.reenigne.org\/blog\/wp-json\/wp\/v2\/tags?post=511"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}