[botribun]

Hello, it would be nice to be able to set the Subtitle frame rate right in the subs adjust osd menu. Sometimes I have a 25 fps video but a subtitle with 23.976 fps and everting is out of sync. There are few tools to fix this, but its getting a tedious job to turn on your PC do this all the time. Could this be implimentet into XBMC per default, so you just download the sub with your remote and select the right sub frame rate eg. > 15 > 20 > 23,976 > 23,978 > 24 > 25 > 29,97 > 30, without the need to convert the srt files at yout PC all the times.

Thanks in advanced!

// Edit Subject

[Ned Scott]

I was always under the impression that most subtitles are time stamped based, not framerate based.

[botribun]

I was always under the impression that most subtitles are time stamped based, not frame rate based.

I don't know exactly but with XBMC the subtitles will get out of sync if you have different frame rates. Eg, your video is 25 fps but the subs are made for a 23,978 fps video, the timestamps will not match somehow and the subtitles moving far ahead as later the movie goes.

To fix this I used the SubtitleCreator tool and convert the fps, but as said before if you have a lot of TV shows with different frame rates its really getting a demanding job. (specially when you have a impatient wife)

So what I'm asking is, would it be possible to add some frame rate setting for the subtitles, that do some kind of live converting the timestamps to match the frame rates and not running out of sync?

[ilomambo]

I second botribun motion.
Although Ned is right, most subtitles are timestamped, it would be a very useful feature to re-stamp them according to a higher/lower FPS ratio.

The same way we can now delay/advance the subtitles up to 10sec to each side, it would be nice to have another option, to compress/expand the subtitle FPS.
Since subtitles are only a few hundred text lines, this timestamp processing is not a heavy burden.

Today, they way I deal with non-FPS-matching subtitles is to download them outside XBMC, re-stamp them, go back to XBMC, restart the movie/series I was watching, re-load the re-stamped subtitle and if it still does not match, repeat the process. Having this done on the fly without having to stop the movie or leave XBMC would be a big improvement.

[ghizzu]

+1

[botribun]

Thanks ilomambo, that was exactly what I've tried to explain!

[takoi]

I was always under the impression that most subtitles are time stamped based, not framerate based.

They are time based; that's the problem. Most frame rate conversions are speedup/slowdown so the timing change, and you need to do the same conversion with subtitles. +1 on this.

[davilla]

We can delay/advance the subtitles up to 10sec to each side because that's just an easy offset to the supplied timestamps. So this is quite easy and not the same at all as changing the actual timestamps.

Change the actual timestamps to a different frame rate is much, much more tricky. ie there's a huge difference between 23,978, 23,977 and 23,979 after a few hundred/thousand frames. You will have a/v subtitle sync issues, guaranteed.

[da-anda]

how can a timestamp differ, shouldn't it be independet from frames? Or how do we internally calculate the current timestamp?

[ilomambo]

how can a timestamp differ, shouldn't it be independet from frames? Or how do we internally calculate the current timestamp?

Good question. 1 second is 1 second at any frame rate.
In reality, anyone that has loaded a subtitle experienced sometimes a loss of audio/subtitle sync, and gets worse as the movie goes on, as if the lagging was cumulative. This is a fact, it happens.
So regardless of how we call it, having the option to correct the subtitle lagging on screen, I think, is a very good idea.

[takoi]

No. Let me repeat: if video B is a speedup/slowdown of A (which 90% are) 1 second in A is not the same frame as in B at time 1sec. It's opposite: if a subtitle is based on frame number, it will be independent of playback speed.

[Ace]

For example NTSC/PAL: https://en.wikipedia.org/wiki/576i#PAL_speed-up.

[da-anda]

ah, you're talking about using subs created from a video source with different framerate, in this case timestamps ofc differ

[botribun]

Maybe just add a option like "ignore video/subs frame rate" and only use the time stamps instead?

[davilla]

Don't forget, not all subtitle formats are handled the same. XBMC has several subtitle codecs that handle the various flavors. This is not a trivial problem so please stop treating is as trivial.