converting audio 29 fps to 25 fps

[thecrock]

I have coverted a movie from 29.970 to 25 fps for pal playback. The audio file is the correct length but the sound is not good, it sounds slow and drawn out. I tried changing from mp3 to wav and encoding from 29 fps to 25 fps with besweet but the audio still sounds slow.

So in a nutshell I have a dvd compliant mpeg video file at 25 fps and wav and mp3 files of the audio running at 29.970 fps.
I have converted with besweet with no problems in the past. I used the ntsc to pal settings.
Perhaps I have altered some settings in besweet by mistake?

Screenshot from besweet.

[adam]

Short answer:
Use the NTSC->PAL (23.976 to 25.00) option instead and it should be perfect.

Long answer:
That 29.97 option in BeSweet is very misleading and I honestly don't know why its there. You'd never need to slow audio down by that much (~30 to 25fps) and for that matter, to convert NTSC to PAL you are supposed to be speeding up the sound not slowing it down.

See, film originates at 24fps and to convert to NTSC you slow it down to 23.976fps and then telecine it. The runtime stays the same, meaning the audio speed stays the same, yet new frames are created every second to increase the fps. Thus even though NTSC runs at 29.97fps its better to think of the audio as being synced to the 23.976fps source.

When film is converted to PAL the video AND audio is sped up by 4%. So PAL at 25fps actually runs faster than its 29.97fps NTSC counterpart. So to convert NTSC->PAL you'd actually (correction- speed up) the audio playback speed by 4% regardless of whether your video is stored at 29.97fps or 23.976fps (called 29.97fps internal because it will be telecined to 29.97fps at playback.)

[manono]

Hi-

Nice post. Just a minor nitpick:

So to convert NTSC->PAL you'd actually slow down the audio playback speed by 4%

Maybe you mean to say, "...you'd actually speed up the audio by 4%..." or some such.

...(called 29.97fps internal because it will be telecined to 29.97fps at playback.)

Hehe, you've been using TMPGEnc for too long. Where I come from progressively encoded 23.976fps with pulldown applied is called soft telecine. That's as opposed to already telecined film encoded as 29.97fps interlaced. That's hard telecine. Based on thecrock's description, I'm not sure how he did the conversion. I hope the former, and not the latter. And I hope his encoder didn't just blend it all to hell, in which case he doesn't have to adjust the audio at all.

[adam]

Yes that's what I meant, speed up.

I actually never use TMPGenc anymore, not for some years. 29.97fps internal is a technical term used in many mpeg white pages, its not just another example of a TMPGenc engrish label. It specifically applies to video stored at 23.976fps and decoded at 29.97fps.

Soft telecine is just a term used to describe a stream flagged to be telecined to something else at playback. Its not specific to 23.976fps footage, though that's definitely the most commonly soft telecined source. You can also store PAL footage at 24fps and flag it with the 2:2 pulldown flag to play back at 25fps and that would be a soft telecine but its not 29.97fps internal as we are discussing here. If you want to go outside of DVDs and look at codecs and software playback then there are dozens of other telecine patterns that could apply. All would be examples of soft telecines.

23.976fps footage with RFF/TFF flags set to decode at 29.97fps is an EXAMPLE of a soft telecine but there are others. I don't know of any other term that applies specifically to 23.97fps pulled down to 29.97fps other than 29.97fps internal, so I'm gonna stick with that one.

[mats.hogberg]

There's also a dedicated soft for this wavworks, that I used when I had a (rare) PAL player that didn't lke NTSC - Most PAL HW do NTSC without probs.

/Mats

[manono]

Hi-

I actually never use TMPGenc anymore, not for some years. 29.97fps internal is a technical term used in many mpeg white pages, its not just another example of a TMPGenc engrish label. It specifically applies to video stored at 23.976fps and decoded at 29.97fps.

OK, but I had never heard that term before, except for the TMPGEnc settings. My ignorance, stemming from just working on the computer with AViSynth and DGPulldown to telecine from unusual base framerates. Based on the way the name sounds, it also sounds exactly like soft telecine, as it seems to apply to every frame rate from 19.98 up to 29.97fps that's been through some sort of pulldown to output 29.97fps. "29.97fps Internal" Doesn't that sound like it could encompass any base framerate telecined for 29.97fps output, and not just 23.976fps? What do you suppose they'd call a PAL 25fps source telecined to 29.97fps for NTSC DVD? I don't think they'd come up with a new term for it.

Doesn't 29.97fps Internal imply there's also a 29.97fps External? Which is what? Hard coded 29.97fps movies? In that context, that term makes no sense. Soft and hard telecine are just more intuitive sounding to me. So, you stick with your term, and I'll stick with mine. And I apologize for the TMPGEnc crack. I didn't mean to sound patronizing.

[thecrock]

Wow, a lot of info to trawl there. Glad the solution was at the top of the post adam.

Thanks to everyone will post back and tell you how i got on.

[poescp]

hello, is there a way to keep the audio the same length as the original, meaning withou 4 % increase.
having speeded up my film by 4 % the voices are faster and higher and a bit noticable.
there must be someway to convert from ntsc to pal and still have the same length audio.

see also post https://forum.videohelp.com/viewtopic.php?t=303494

[adam]

Changing both audio and video speed, thus resulting in physically faster playback, is the proper way to do the conversion. For the vast majority of sources you really should not be able to detect the speed change. You say that its noticable because you know its there, but you should know that its there in just about any PAL source in existence. The vast majority of commercial footage is shot in film at 24fps and sped up to 25fps. Its just how PAL is done.

The only way to avoid the speed change is to increase the fps by duplicating frames (or fields) instead of speeding things up. This results in jerky playback and is the type of thing that most people would probably notice just from casual viewing. If you still want to try it then you can usually accomplish this just by encoding to your target framerate in your mpg encoder. You can use Procoder or TMPGenc with the "do not framerate conversion" filter unchecked and it will duplicate one frame every second.

[jman98]

poescp - I believe that what better authored PAL DVDs do about the sound speedup is that, yes, they do speed up the sound 4% but then they use an audio editing program to lower the pitch so that the faster audio now sounds identical to the original audio, even though it is a little bit faster. I can't provide any examples on how to do this, but perhaps a web search would help.

[Cornucopia]

2 that I use most often: ProTools & CoolEditPro.

In PT: Select Audio (whole thing), [AudioSuite] "TimeCompress/Expand"--with PitchAdjustment/Compensation

In CoolEdit: Selection Audio, [Effects] "Time/Pitch" | "Stretch" --with constant stretch, "TimeStretch" mode (High Precision pref.)

These are the %s:
PAL(25)-->Film(24) = 100.416666%
PAL(25)-->Film(23.976) = 100.42709376%
Film(24)-->PAL(25) = 96%
Film(23.976)-->PAL(25) = 95.904%

HTH,
Scott