How to avoid palimpsest (Ghost captions)?

[Djard]

In my project, I have the lyrics to a song in an overlay track, with space between the captions (no overlapping). Yet I get part of one word faintly recurring in ensuing captions. Is there a way to correct this problem?

[pandy]

Try reduce subtitles level (i mean instead pure white use light gray) - there is a chance that your recording device has some form of AGC and it may be over-steered by too high signal level if this signal occupy only limited amount of screen.

[Djard]

Thanks for responding, and the clever idea to use a less intense tone. I find it odd that this problem has not surfaced in previous projects, wherein I have used the same settings without any bleeding.

[pandy]

This is more complex problem - depends on hardware vendor and software quality it may be few different problems - at first normally capture HW expect active video to be 700mV and 300mV sync pulses so 1V (1000mV) in total - then to maximize conversion dynamics analog frontend may adjust gain to use as much as possible bits in Analog-Digital Converter. It can be case where Average Picture Level calculated by capture HW is lower and ADC is over-steered by high local signal (subtitles) - reducing subtitle level may help in such case.

[Djard]

I fixed the problem: the rogue text that kept re-appearing in subsequent captions was in the Title that VS added when I started the project. I simply deleted the contents of the Title track, and the ghosted text disappeared. I used a prepared photo for my title page anyway.

[pandy]

I fixed the problem: the rogue text that kept re-appearing in subsequent captions was in the Title that VS added when I started the project. I simply deleted the contents of the Title track, and the ghosted text disappeared. I used a prepared photo for my title page anyway.

Check how your software deals with alpha channel - seem alpha is not fully deactivated (or it may be case full quantization range vs limited quantization range - 0..255 vs 16..235 - if alpha is in full quantization range then it may be active when instead black level 0 your setup use black level 16).