ffmpeg scroll text without gap

Question

I'm using this command to scroll text on video

"drawbox=y=ih-108:color=blue@0.4:\
width=iw:height=48:t=fill, \
drawtext=textfile=file.txt: \ 
fontfile=OpenSans-Regular.ttf: \
y=h-line_h-65:\
x=w-mod(max(t-1.5\,0)*(w+tw)/18.5\, (w+tw)): \
fontcolor=white:fontsize=36" \

This scroll runs in loop with gap. When all the text is scrolled on video [there's a gap] then it restarts the scroll.

I want scroll to run continuously without any gap like in this video - https://www.youtube.com/watch?v=Z0ZpLAgpghk

Is there any other filter to accomplish this or how do i modify the x= expression to get desired output?

Answer 1

You can achieve this by chaining two drawtext filters

"drawbox=y=ih-108:color=blue@0.4:\
width=iw:height=48:t=fill, \
drawtext=textfile=file.txt: \ 
fontfile=OpenSans-Regular.ttf: \
y=h-line_h-65:\
x=w-mod(max(t-START_TIME_OFFSET\,0)*(SPEED)\, 2*(tw+MARGIN)): \
fontcolor=white:fontsize=36, \
drawtext=textfile=file.txt: \ 
fontfile=OpenSans-Regular.ttf: \
y=h-line_h-65:\
x=w-mod(max(t-(tw+MARGIN)/(SPEED)-START_TIME_OFFSET\,0)*(SPEED)\, 2*(tw+MARGIN)): \
fontcolor=white:fontsize=36"

START_TIME_OFFSET is the initial time when the text appears e.g. 1.5 seconds.
SPEED is the scrolling distance for one character per second e.g. 100 pixels or 1/10th the width, w/10.
MARGIN is the distance between the end of one scroll and the start of the next e.g. 100 pixels or proportional distance w/5.

For this method, text has to be equal to or wider than frame width.