1. Change the Movie Header timeScale in ‘mvhd’ to $00000271 2. Change the Sound trak timeScale in ‘mdhd’ to $0000c350 3. Change the Video trak timeScale in ‘mdhd’ to $00000271

Just tried it with a previously exported file. original Video trak timeScale in ‘mdhd’ shows

$00007835 ($00000004) $00005dc0

(24000) instead of 600 on your screenshot. The change results in dodgy audio and the video only appears ( in extreme slow motion) 2 minutes after the beginning of my 3 minute file.

This is bound to happen. I know Final Cut Pro uses 2400 as the timeScale. If this export was from Avid, maybe it was an earlier version of Avid and Quicktime?

If you have 2400, you can try chaning it to 2500; you will need to play around with the string value to find what 2500 is though.

These methods are really very simple hacks, they will only work if you have the exact same start values as I had, if not then you need to figure out what values you need to enter. Its all relative to the start point.

- 24fps timeScale at 600 would become 625 at 25fps
- 24fps timeScale at 2400 would become 2500 at 25fps

Audio timeScale is based on samples - if you start with 48khz (48000) audio at 24fps, you need to enter 50khz (50000) for 25fps.

If you start with 44.1Khz then you will need to figure out what the resulting value is when moving the Quicktime file from 24fps to 25fps playback speed. I can check this out later if you need.

Good luck
Mark

I'd appreciate it. This export was from a rather new version of AvidExpressPro. Dunno about the QT version, though.

OK, I have updated the two pages with the values to use when you have files with 2400 or 24000 starting points. However the PC version of Dumpster seems to have issues with files which have header timeScale's of 600 and Video trak timeScale's of 24000.

On the Mac version you can make the changes to these mixed files and get the nice 25fps file with sped up audio, but on the PC version, the file seems to convert OK, but actually the image becomes cropped to a quarter of the screen - it seems to be OK apart from this. So the PC workflow is no good when you have those sorts of files I'm afraid.

With regard to why sometimes 600 is used and other times 2400 or 24000 is used - Avid does appear to use 24000 when you do a self contained Quicktime export, so try using a QT ref instead.

So the bottom line is the Mac version seems to be easier to use, more reliable and has better handling of these varying files. Nothing I can do about that I'm afraid.

--Mark

Mucho thanks. But as for QT-ref, isn't that only an exchange format to other Avids? I mean, will an east-European lab with an unknown computer platform be able to play it?

Only use QT Ref if you are going to be using that file for another purpose on that machine / network - such as encode a DVD.

If you are sending it to a lab for a conform etc, then you should make a self contained QT and maybe get a Mac to alter it with Dumpster:-)

Or get the lab to except a tape and just use Avid's built in 25fps digital cut !!

Good luck
Mark

I find it strange that there's been no more said about this since 2006!

mark.burton:

It seems that by using Dumpster you can alter only a few values in a Quicktime file to make it play at 25fps instead of 24fps. This way you can export a 24fps Quicktime reference file from Avid (much faster) and by making four value changes to the file in Dumpster (takes 20 seconds) it will now play with 1:1 frame acuracy at 25fps with audio also sped up to match. Perfect for making DVD's with no pulldown.

I made a quick webpage to explain this procedure for the Mac, see if it works for you:
Convert 24 to 25 Mac

--Mark

This looks like a good work around solution to the problem I'm currently having.  The only problem is the link is broken, can you Mark or someone please post the procedure for me.

Many thanks,

Baz.