[MPlayer-users] ASS move jerks

[Phil Oleynik]

Evgeniy Stepanov wrote:
> I've switched pos_x/pos_y to double and it moves much more smoothly now. It 
> now jumps by screen pixels instead of script pixels.
>
> Taking it one step further and achieving subpixel precision would not be that 
> easy.
> 1. The subpixel part of screen coordinate has to be known before the first 
> glyph is extracted from font, otherwise it will not be hinted correctly. 
> \move and \pos can appear anywhere in the line, so we either need some kind 
> of preprocessing, or delay glyph extraction until all the line has been 
> parsed.
> 2. More importantly, \move will be slow as hell, as it will need to render the 
> line from scratch for each frame.
>   
I suppose 0.5 pixel accuracy will be enough for everything,
so four glyph caches will be sufficient for smooth move,
one with integer coordinates, and others with 0.5 shift in all directions.
Otherwise it will be slow as a drunken snail.

Best regards, Phil