Audio delay/echo issue

Hi Graeme,

Unfortunately, our sound mixer, Brandon, called Sound Devices and he didn't get the name of the person he was talking to because he gave them his email address. Sound Devices said they would email him with more support info but they haven't.

Brandon will be contacting the sound tech at the studio we've been filming at to get more technical info on the setup and I will relay that to you when I have it.

Reuel,

Can you pass on details of your contact at Sound Devices, and/or a support case number and can you also provide any and information about how the file was created?

Thanks we will do that.

We've contacted Apple already (but not given them your file yet as we were waiting for permission) and they have said that they are happy to have a conversation with Sound Devices, to explain what really is the problem.

You said you contacted Sound Devices already. Can you pass on details of your contact, and/or a support case number? It might be worth sending those details in a private message.

Can you also provide any and all information about how the file was created (e.g. what Sound Devices model/any settings/etc).

Sure, that's fine. Thank you.

Is it okay to send the mov file to Apple for them to look at?

Reuel,

Sorry for the late reply, I only just saw your PM. I have passed the file on to the developers so that they can check if it is the exact same issue as audiochick was having with the AJA file. I'll update you when I get a response.

We contacted Sound Devices and they're claiming it's a known QTKit issue and that this problem occurs across devices that record Quicktime files in 24-bit. I'm not sure if that's entirely true but it seems like they're not interested in addressing this problem on their end.

Hi Reuel,

It looks like it's the same thing then, but it would be best to get hold of a copy of the file to be sure. I've sent you a PM with FTP details.

Changing from using QTKit to AVFoundation to extract the audio would be a very big change to the way that the app works so I wouldn't like to say if/when that will happen. I know it has been talked about here, but it would require a lot of development and QA.

Although it's clear that this only happens in QTKit and not AVFoundation, the problem appears to be with the mov file missing some information that should be there (if it is the same thing). AVFoundation is just more tolerant of this than QTKit. For this reason, it might be worth contacting Sound Devices because they created the mov file.

If we can confirm that this is the same issue by looking at the file, we would be happy to explain to Sound Devices what Apple says is missing from the file. In the meantime, perhaps you could report the issue to the vendor that their files don't play correctly in QT7 to get the ball rolling?

- Graeme

Hi Graeme,

I can confirm that Quicktime Player X does not exhibit a delay when playing back the video files but Quicktime Player 7 does. I can send you a clip to check out. Please let me know how I can send it to you privately.

If this is an issue with QTKit, is there a possibility of you guys moving your code over to AVFoundation in the near future?

Reuel,

What does the audio sound like if you play it in QuickTime Player 7? (You can download it from support.apple.com/kb/DL923 if your system is to new to have it by default)

Would you be able to provide a clip that causes this issue so that we can check if it is caused by the same issue?

Just to raise visibility, we're having this same problem in our workflow as well. The delay/echo problem sounds like phasing. We're using multiple Sound Devices PIX recorders, however, not KiPros. Also recording 24-bit audio to ProRes Quicktime files. We worked around the issue by transcoding the source files to 16-bit audio.

Got it - thanks. We'll contact AJA soon.

Yes please! I will send you contact info. Thanks!

Audiochick, Mads,

This audio delay/echo also occurs when you play the file in QuickTime Player 7 (it plays fine in QuickTime Player X).

We have been told by Apple that the reason that the audio corruption occurs is because there is some missing information in the QuickTime wrapper.

We are happy to raise a bug report with AJA, and put them in touch with the Apple engineers that have told us what information was missing from the QuickTime wrapper, but before we do so, we would like be able to include all the relevant information. You have already said that your files were created by an AJA KiPro Quad and were Apple ProRes 422 (HQ) files, with two mono channels of 24-bit PCM audio at 48kHz, but is there any other information that you can give (e.g. versions numbers)?

Would you be happy or us to pass your contact details to AJA in case they need to ask for any more information?

Mads,

Can you please describe how your clips that exhibit this issue were created? Were they also from an AJA capture?

Graeme