SyncMySubsFix subtitle reading speed
When a subtitle flashes on screen for a fraction of a second, you can't finish reading it before it's gone. Set a minimum display duration and this tool stretches every too-short cue up to it, stopping short of the next cue so they never overlap. Set a maximum too if some lines linger too long. It all runs in your browser.
Set a target reading speed and each cue's minimum scales to its text length, so a dense line gets more time than a short one. The minimum duration above then acts as a floor. Leave it off to use the flat minimum on its own.
Why cues that flash by are hard to read
Reading takes time, and a subtitle that appears for half a second is gone before your eyes reach the end of the line. It happens a lot with fast dialogue, auto-generated captions, or files that were split from a longer cue. A sensible minimum duration gives each line enough time on screen to actually be read.
This tool checks the length of every cue and lengthens the ones below your minimum by pushing out their end time. It only extends up to where the next cue begins, so nothing collides. For a smarter check, set a target reading speed in characters per second and each cue's minimum scales to its own text, so a long, dense line that clears a flat minimum but is still too fast to read gets caught too. Set a maximum and it will also trim cues that hang around too long. Only end times move, so SRT, VTT, ASS, and .sub files keep the rest of their timing, text, and styling.
FAQ
What is a good minimum duration for subtitles?
Around one second is a common floor, and many style guides go a little higher for longer lines. Anything much shorter tends to flash by before you can finish reading it. Start at one second, watch a scene, and nudge it up if lines still feel rushed.
What's the difference between a minimum duration and a target reading speed?
A flat minimum gives every short cue the same amount of time, which is simple but can miss a long, dense line that clears the minimum yet is still too fast to read. A target reading speed, in characters per second, scales each cue's minimum to how much text it holds, so a packed line gets more time than a couple of words. Turn it on and the minimum duration becomes a floor for very short cues.
Will extending a cue make it overlap the next one?
No. A short cue is only stretched up to the start of the next cue. If there isn't enough room to reach the full minimum, it extends as far as it can and stops there, so two subtitles never end up on screen at the same time by accident.
Does it change the timing of cues that are already fine?
No. Only cues below the minimum (or above the maximum, if you set one) are touched, and only their end time moves. Start times, text, order, and everything else in the file stay exactly as they were, and it saves back in the original format.