FPS question

[pfxz]

What exactly is FPS? If I think of it as "Frames per Second," I just can't figure this one out.
My question stems from out-of-sync audio and subtitles.

.SRT subtitles for example don't use frames for timing, but actual time (hours:minuteseconds,miliseconds). Supposing that a video plays at normal speed (whatever the FPS is), shouldn't the subtitles always be correct?
And sometimes the audio goes out of sync as well, being OK in the beginning and gradually losing sync towards the end.

So, assuming that audio and subtitles have a fixed (and correct) length but the video goes out of sync, is it safe to conclude that the video has incorrect FPS?

[filmboss80]

Yes, FPS is Frames Per Second. You should not assume the problem is with the video stream. There are many other variables that can cause the loss of sync. However, it is impossible to assess your situation because you provide absolutely no useful information about the video type. Is it a DVD (VOB, MPEG), AVI (Divx, Xvid) file, etc.? Did you perform any analysis using G-Spot (freeware under the Tools section) concerning frame rate? Did you check to see if the audio stream was VBR (Variable Bitrate) or CBR (Constant Bitrate)? We can't help you unless you can tell us more about the video.

[pfxz]

Well, my question doesnt concern a particular situation or anything; it is just a general question about FPS. I can usually fix the sync editing subtitles or by changing the FPS in the video file (I usually dont mess with the audio stream), but I was wondering if I could pinpoint the cause of such problems to the video's FPS setting.

Thanks anyways.

Oh, and is there any tool similar to G-Spot that will work with MKV files?

[poisondeathray]

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