Re:R.T. Russell's Z80 BBC Basic Is Now Open Source
by gugagore on Saturday June 15, 2019 @12:02PM
(#20190588)
The process seems fairly DSP intensive. If I recall, the IQ modulated color signal would leave a dot pattern in the luminance signal. I wonder how many frames it could process a second, if written in BASIC.
Re:R.T. Russell's Z80 BBC Basic Is Now Open Source
by mikehall314 on Saturday June 15, 2019 @04:14PM
(#20191866)
From memory, it would do 1.5 frames per second.
For background: many programmes produced on colour videotape by the BBC in the 70s, were distributed to overseas broadcasters on black and white film only. When the BBC destroyed the original videotapes, this left the black and white films as the only remaining copies of these programmes. In some cases, however, the colour information had been accidentally embedded into the black and white film (a notch filter should have been used to remove it).
So around 2008, Richard developed a piece of software, in BBC BASIC, which was able to recover the embedded colour signal and restore several programmes held in black and white to their full colour glory.