While an input is locked, single-shot deviations of the frontend
measurements (line count, field period beyond PCNT_TOLERANCE, hsync width
beyond HSYNC_WIDTH_TOLERANCE, activity flag or the validity check) make
get_status() re-program the mode or drop sync. A NeXT SoG source produced
such glitches (868 -> 814 -> 868 lines) every few minutes, each one a
visible blink.
With this option on, a deviation is acted upon only once it has been seen
on three consecutive status reads; the first two deviating reads are
replaced by the previous stable values. That is 30 ms in the normal case
and up to about 105 ms if the vsync wait in get_status() times out on every
read. Counting deviating reads (rather than requiring identical readings)
guarantees that a real mode change or sync loss is always accepted on the
third read. The counter is cleared whenever the input is not locked or the
option is off. Default Off (stock behaviour). Stored as profile item id 69.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WiXHy7Jhh5yTdsBaenucgw
tvp_source_setup() disables the TVP7002 internal H-PLL coast for every
PC-type preset. That is right for RGBHV, but with sync-on-green or
composite sync the serration pulses during vsync disturb the H-PLL every
frame; on a NeXTstation Color (1120x832, SoG) this caused continuous
horizontal jitter, jitter in the top third of the picture and a periodic
HDMI re-sync. With the option on, coast is re-enabled after setup when the
sync source is SOG or CSYNC; RGBHV is untouched. Default Off, so existing
behaviour is unchanged. Stored as profile item id 68.
On the NeXT, this option together with the existing settings Analog sync
LPF = 10 MHz, ADC PLL BW = Low and H-PLL Pre/Post-Coast = 4/4 ran 19
minutes without a sync loss, mode re-program or IT6613 video-stable
change. SPARCstation 20 framebuffers (ZX, TurboGX) over composite sync are
stable without it.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WiXHy7Jhh5yTdsBaenucgw
marqs