Exporting video with 24 bit audio - which Quicktime codec will give me a smaller final file?

[rachel320234447hep]

Hello

I need to deliver a video with 24 bit audio. So I'm using Quicktime instead of H.264. I've tried two of the settings but both are creating massive files (35GB for 14 minutes isn't feasible for my purposes). Is there a setting / technique someone can recommend to preserve the 24-bit audio but reduce the overall file size? 

Thank you. 

[Jeff Bugbee]

If you're using the QuickTime format, you still need to set a codec. What codec are you currently using?

[R Neil Haugen]

If you simply want the smallest file sizes, then perhaps the ProRes LT or proxy.

The intraframe codecs like ProRes, Cineform, and DNx all have variants depending on compression rates. Starting with 4444 w/Alpha on top, and a proxy type as the lowest. You can find their data bitrates online.

[rachel320234447hep]

Thanks for these ideas, I'll switch to one of those, and check out the rates as you suggest. 

[rachel320234447hep]

I tried many exports, all of which claimed to be exporting audio at 24 bit. What I then discovered - with a mass of exports - was that none of them actually did that. The results are 32 bit. 

This seems to be a problem with Adobe.

[R Neil Haugen]

I am still trying to figure out why the need for 24 bit audio. That is, if the problem is the ending file size. Audio tends to be a rather smallish part of the overall file data.

It's the video part that takes the most space. By far. So ... what is the need here?

[rachel320234447hep]

I have to deliver 24 bit audio for a particular user, client if you like. That is the brief. 

Well, it was. But ultimately I delivered 32 bit audio in the movie. I gave them separate audio of 24 bit as well. I don't have software enabling me to deliver as I hoped.

[R Neil Haugen]

Understood. Client specs ... 😉

[Warren Heaton · Accepted solution]

ProRes has predictable file sizes based on the target data rates.

1080p30 ProRes 422 HQ is about 1.3GB per minute and 1080p30 ProRes 422 LT is about 700MB/per minute.

The appendix starting on page 19 of the Apple ProRes White Paper provides target bandwidth/file sizes in GB per hour at common frame sizes and frame rates.

As far as getting 24-bit audio goes with ProRes in a QuickTime file goes, you should be able to get this by starting with a ProRes QuickTime preset and changing the audio sample size from 16 bit to to 24 bit.  

[rachel320234447hep]

Thank you for the reference! 

I did export using QuickTime ProRes and I changed the audio setting to 24 bit. I checked it all in the plane showing source and output settings. 

However, even after trying multiple times, my resulting audio had been resampled to 32 bit. I checked every export with the use of audio software. 

Although I am working with video, my main concern is audio. I cannot deliver audio that has been resampled in this way.