H264 PAL to NTSC Advice

[Kripsy]

I am attempting to encode some of the 1080p H264 files to x264 for storage and playback reasons, but they are all PAL which begs some questions. Should I convert the FPS from 25 to 23.976 and if so, what is the best way to do this? Is it possible to change the frame rate of a video after I already encoded it to x264 so I don't have to re-encode it? I know there is a pitch shift to compensate for the faster fps so I assume I would want to slow the film down to standard frame rate just to make the videos compatable with most DTS tracks.

Now, I am not so versed in movie framerates, so bear with me here. I have a H264 1080p Serenity cap that is 25 fps and has some noticeable frame "skips" during slow pan scenes such as the beginning montage when compared to my NTSC DVD. Is this due to the frame rate or is the original broadcast just messed up? I can make a sample if needed.

Thanks in advance.

[Mug Funky]

slow the film down to standard frame rate

25fps is a standard frame rate.

unless it's not playing in your equipment, there's no need to re-encode.

as for the frame skips, it's a matter of how the film was transferred to PAL. there's basically 3 ways to do it (more if you count things that should not be attempted because they suck).

1. 24fps sped up to 25p, with audio resampled (or timestretched).

2. 24fps put into 50i by duplicating 2 fields every second (if you're seeing 2 slight jerks per second, this is why). footage will be half interlaced, half progressive.

3. 24fps put into 50i by "field blending". this is where the 50 fields per second all contain a weighted average of adjacent frames. motion is smooth, but slightly ghosted if you look hard enough. footage will be interlaced all the way through.

the vast majority of films out there in PAL are the 1st method. 2 and 3 are rare (though 3 comes up a lot in DVD land, as hardware NTSC to PAL converters will do this from the NTSC source).


you'll want to deal with these issues before encoding to x264, though i'd advise not changing anything unless you can't play PAL on your hardware (in PAL land you can play anything, but in NTSC land you can often only play NTSC). 25fps should be perfectly compatible with DTS - the audio part doesn't care what standard the video is in unless there's embedded timestamps, and even then it's not a problem.

[Kripsy]

I haven't tried syncing the DTS track from my NTSC dvd yet, but the AC3 that is apart of the encode is deffinitely sped up, not slowed down. Does this mean that the PAL audio track is the actual speed and the NTSC track is slowed down if 25 fps is the standard? I thought someone told me the direct opposite so now I am confused :confused: .