Fix 24 fps Subtitles to 25 fps
Or paste subtitle text
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Which frame rate the timings are counted in. On the format pages this is what MicroDVD needs, because it stores timing as frame numbers. On the frame rate pages it is the rate the file was timed against — the version the subtitles were made for — and the page's second box takes the rate of the video you are going to use them with. 23.976, 24, 25, 29.97, 30, 50, 59.94 and 60 are the common ones. Getting it wrong shifts the whole timeline, and on the frame rate pages it shifts it by a ratio rather than by a fixed amount.
The frame rate of the version you are going to use the subtitles with — the video you are actually going to play. The factor applied is the first box divided by this one, so 24 into 25 gives 0.96: a film runs 4% faster on PAL, and a 100-minute feature fits a 96-minute tape. Getting the two boxes the wrong way round shifts the whole timeline in the wrong direction by the same amount.
This page takes a subtitle file timed against a 24 fps film master and puts it on a 25 fps PAL version. Every timestamp is multiplied by 24 divided by 25, which is 0.96 exactly, so the whole timeline comes out 4 percent earlier and every cue is 4 percent shorter. The two boxes are already filled in; change them if your file is timed against something else.
This is the pair the phrase PAL speed-up refers to. Film is shot at 24 frames a second and European television replays it at 25, so the same pictures run 4.167 percent faster on the clock and a 100-minute feature fits a 96-minute tape. Nothing about the film is changed and no frames are dropped: the pictures are identical, and a subtitle file timed against the film has to run at the tape's speed to stay with them. That is what 0.96 does, and it is the one ratio in this group you can work out in your head.
Two things people notice about PAL speed-up are outside this page's reach. The audio, if it is carried over unchanged, plays 4 percent fast and rises in pitch by roughly 70 cents — a little under a semitone. And the reading speed of every subtitle goes up by 4 percent with the timings, because each cue is given less time while the words stay the same length. If the file is being prepared for broadcast, that second one is worth checking against the limits before you ship it.
If your film master is not a true 24 but the 23.976 that an NTSC release carries, the factor is 0.95904 and the pair has its own page in this group; the two differ by 0.1 percent, which is 3.5 seconds an hour. Nothing is uploaded, and a whole season goes through the queue in one pass — SRT, WebVTT, ASS, SSA, SBV, SAMI, MicroDVD, TTML, JSON and CSV files are read as what they actually are rather than as the extension suggests.
Examples
The four percent, in full
Input
1
00:00:01,000 --> 00:00:03,000
Hello there.
2
00:01:00,000 --> 00:01:02,000
One minute in.
Output
1
00:00:00,960 --> 00:00:02,880
Hello there.
2
00:00:57,600 --> 00:00:59,520
One minute in.
0.96 is 24 divided by 25. The cue at one second loses 40 ms and the one at a minute loses 2,400 ms — sixty times the distance from zero, sixty times the movement. Both edges of each cue are multiplied, so a two-second line is given 1.92 seconds, which is where the reading speed increase comes from.
A feature that ends four minutes early
Input
1
00:01:00,000 --> 00:01:02,000
One minute in.
2
01:40:00,000 --> 01:40:03,000
The last cue of the feature.
Output
1
00:00:57,600 --> 00:00:59,520
One minute in.
2
01:36:00,000 --> 01:36:02,880
The last cue of the feature.
A 100-minute feature runs 96 minutes on the PAL tape and 95 minutes 54 seconds if the master was 23.976 rather than 24. This is the check worth doing by hand after converting: open the PAL file at the last cue's new timestamp and the line should be there. If it is, every cue before it is right as well, because the error being corrected is a proportion of the clock rather than a fixed offset.
A MicroDVD file changes only its declaration line
Input
{1}{1}24
{24}{48}Hello
Output
{1}{1}25
{24}{48}Hello
MicroDVD stores timing as frame numbers, and PAL speed-up replays the same frames at a different rate — so frame 24 is still frame 24, and the file's first line is what changes. Rewriting the frame numbers to 23 and 46 would apply the 4 percent twice, since the player already knows to read them at 25.
Frequently asked questions
Why is the factor for 24 to 25 exactly 0.96?
Because it is 24 divided by 25. PAL replays the same pictures 4.167 percent faster, so the running time is 96 percent of the film's: a 100-minute feature fits a 96-minute tape, and every timestamp keeps 96 percent of its value. Nothing is rounded here and nothing is approximated — 0.96 is exact, which is why this is the one pair in the group you can check in your head.
What does PAL speed-up do to the audio?
If the soundtrack is carried over without correction it plays 4 percent fast and rises in pitch by roughly 70 cents — a bit under a semitone, which is why voices on some European releases sound slightly high and hurried. That is a separate problem from the subtitles, and it is not something this page can fix: the subtitles have to follow the pictures, so the ratio here is 0.96 whether or not the audio was corrected.
Is 24 to 25 the same as 23.976 to 25?
No, and the difference is 0.1 percent: 0.96 against 0.95904, which is 3.5 seconds an hour and 5.5 seconds over a 95-minute film. Which one is yours depends on what the file was timed against. A film master runs at a true 24; an NTSC release of a film runs at 23.976, which is 24000/1001. Using the wrong one leaves a residual error that grows towards the end of the file.
How do I get back from 25 to 24?
Put 25 in the first box and 24 in the second and the factor becomes 1.0416667, which spreads the timeline back to the film's running time. The group has a page for that direction as well, and it is the one to use when a PAL subtitle file has to go back onto a film master — as opposed to onto an NTSC release, which is a different page and a different number.
Why does a PAL release of a film run four minutes short?
Because the same frames are shown faster. A 100-minute film becomes a 96-minute tape, so nothing is missing — it is all there, running 4 percent quick. This is also why running times differ between regions in databases: the 96-minute figure and the 100-minute figure describe the same film, and a subtitle file timed against one of them is four minutes out by the end on the other.
Do I need to check the reading speed after converting to PAL?
It is worth doing. Every cue keeps 96 percent of the time it had, so a line that was comfortably inside the limit can be pushed over it, and the words did not get shorter to compensate. The compliance tools in this site measure characters per second against the thresholds the accessibility standards set, which is the number to look at rather than a feeling that the subtitles now seem rushed.