I am making a DCP of a short film of mine for festivals. I was told to convert it to 24 fps for the DCP. I did some reading on how to do that, and I was told that I would need to convert the audio from 48 khz to 48.048 khz to match the 24 pull up.

But in Premiere Pro, I don't have a 48.048 khz option to export with. Does anyone know what to do then?

You were misinformed, you need to keep the sampling rate at 48kHz but you need to alter the speed of the audio.

Oh okay, how do I alter the speed though?

Altering the speed also changes the pitch though, so will that be a problem? Or is there a way of altering the speed, whilst keeping the pitch the same?

You can resample the sound which maintains pitch but it comes at a small quality price.

Sox is a nice and free tool to change the speed and optionally remain pitch.

http://sox.sourceforge.net/

In context, changing the sample rate from 48khz to 48.048khz will result in the audio running at 0.999000999% of its prior speed, or something like that. Ditto for the pitch. That's close enough to 100%.

My guess is that you're not going to notice anything and neither will anyone else. Give it a test without the CPU intensive pitch-maintaining software calculated conversion and see how you go.

Andrew

Okay thanks, but the only way I know how to change the speed is by changing a clip on it's on. Is there a way to change the speed of the whole sequence, compared to every little audio clip individually? I tried watching some tutorials but they only talk about changing the speed on individual clips.

Export the audio out to a single finished file, then apply the changes to that.

Andrew

Do people still produce in drop frame? I thought the NTSC days were over? Being in the UK we get very worried when asked to produce material in NTSC formats, because we have always had to guess if our converted products would actually play in the US. not at the work computer but isn't there a preset for drop frame in media encoder that converts the video AND audio as part of the conversion? I'd worry about doing any conversion as two separate files and hoping they started in sync. I'll have a look later, but I've never heard the 48+ and 48- formats even mentioned for a very long time. Is it still a common thing in the US?

I'm not positive about DCP, but most '24 frame' video is actually 23.976 and compatible with 48k audio. Pull up/down is not needed.. as was the case with cellulose film.

In context, changing the sample rate from 48khz to 48.048khz......
Not sure where this idea comes from that you have to change the sampling rate to change the speed (and or pitch).

It is not true and unwise as 48kHz is the most common audio standard. Keep the sampling rate the same.

I'm not positive about DCP, but most '24 frame' video is actually 23.976 and compatible with 48k audio. Pull up/down is not needed.. as was the case with cellulose film.
DCP is exactly 24p.

thank God for that - I was imagining all kinds of crazy things happening if you had to transcode audio to package it up.

I did have a look in Premiere and Media Encoder and couldn't find any trace of this audio format - so makes sense now. 48K and leave out there!

This article seems authoritative. It's a bit old as it refers to Pro Tools 7.3 as the newest version, but I suspect the issues he's discussing haven't changed.

https://www.trewaudio.com/articles/48048-khz/

Not sure where this idea comes from that you have to change the sampling rate to change the speed (and or pitch).

It is not true and unwise as 48kHz is the most common audio standard. Keep the sampling rate the same.

Changes to duration time and pitch are a side effect of changing the declared sample rate in an audio file. It's a bit like slowing down or speeding up an audio tape playback speed. My very point was that it wasn't worth it to mess around with the sample rate and to leave it at 48k.

Andrew

Okay thanks. But if I leave the sample rate the same, but I convert the footage from 23.976 fps to 24 fps, the sound then isn't as long as the video. So if I am to leave it the same, how do I change the speed then to match the video? Should I just use the rate stretch tool and stretch the audio to length of the video?

I think, if I have followed this correctly, is what people are saying is that you should not try to shoot video in drop frame - it's no longer a valid proposition, so if you record in any of the common versions, then the audio IS 48K, not the .1% difference because there is no dropped frame to be pulled up.

If you record video at 1080 and above at any frame rate above 23fps, then it will NOT be drop frame NTSC, and that is where the problem comes from. 24, 25,30 are all frame for frame accurate. I'm not even sure there is an HD drop frame format now, is there?

Shooting at 23.976fps is pretty standard in NTSC countries (unless shooting film), otherwise you can run into issues with time code and post production can become a nightmare. Many video cameras shoot at 23.976fps, while saying 24 fps as a short hand. I wouldn't bother about pitch changing for this. you probably hear it all the time and don't notice.

In Europe 23.976fps is not issue, because you use whole frames for the time code, so 24 fps can be used and 25fps is for TV (some low budget features uses this). However, shooting at 24 fps may require pitch change because of the 4% speed difference when being transmitted at 25 fps. Even then it may not work with all soundtracks because the process can be objectionable with certain types of music.

thank God for that - I was imagining all kinds of crazy things happening if you had to transcode audio to package it up.

I did have a look in Premiere and Media Encoder and couldn't find any trace of this audio format - so makes sense now. 48K and leave out there!

Potentially yes but pull down and pull up sample rate has always been there since the advent of digital.

Editors liked working with a 30fps timeline so pull down and pull up sample rates were defacto to suit the 29.97 frame rate that was used in TV.

As for HD I would have thought that if you have 1080i 48khz or 25p/30p you just export a 24p version for festivals etc.

The great thing about standards is that there are so many and at AMS Neve when I was there in the early 90's we had to deal with all sorts of chaos as people mixed and matched drop rate timecode and sample rates.

Oh okay, well I keep having issues cause when I try to convert 23.976 fps to 24 for a DCP package, the video is then longer than the audio it seems.

I would check your workflow for doing this, you may find that there is a setting/procedure for this operation..

I suspect you aren't the only person doing the 23.976 fps to true 24 fps procedure with a digitally shot film, so that procedures will be established, if somewhat confusing. https://simpledcp.com/notes-on-frame-rate-conversion may be a starting point.

I think, if I have followed this correctly, is what people are saying is that you should not try to shoot video in drop frame - it's no longer a valid proposition, so if you record in any of the common versions, then the audio IS 48K, not the .1% difference because there is no dropped frame to be pulled up.

If you record video at 1080 and above at any frame rate above 23fps, then it will NOT be drop frame NTSC, and that is where the problem comes from. 24, 25,30 are all frame for frame accurate. I'm not even sure there is an HD drop frame format now, is there?
"Drop frame" or "Non-Drop Frame" does not refer to the framerate but to how the timecode counts frames.