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Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?

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Jonathan Fairey
Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 5, 2013 at 3:54:14 pm

Hi everyone,

I have an interesting problem - exporting a draft video clip for a client has resulted in a clip that plays fine, except for the audio for the first interview.

The interview plays fine both on Macs (on which it was edited), but on PCs, and an android phone, when playing the file from the hard drive or watching it on youtube, the audio for the first interview is "missing" - although artifacts of it can still be heard very faintly. If you plug headphones in to a PC/android phone playing the video either off the heard drive or on YouTube then you can hear the interview audio fine. And it only affects the first clip. Here is a link to demonstrate - the offending clip begins at 0:07:









(This will be useless for Mac users, as it should playback with no issues for them...)

Does anybody have any idea why this might be happening, and what I can do to fix it?

Thanks for taking the time to read!

Jon


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Craig Seeman
Re: Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 5, 2013 at 4:08:58 pm

At the top of this forum there's a Sticky post which you should read.
Without workflow details we can only guess.

YouTube re-encodes so if it sounds fine for Mac users but not for WIndows users from YouTube that would mean an issue with the file you uploaded. Assuming you encoded that first and the issue exists on the desktop it could mean an issue with that encode or maybe in the master file you exported.

We could throw out guesses but it would make more sense if you provided details.
Draft = what?
Encoded that to what?
Use codecs and settings in your description.



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Craig Seeman
Re: Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 5, 2013 at 4:18:05 pm

Playing the YouTube video on Windows 7 Internet Explorer 9, the audio plays fine for me including the first interview.



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Jonathan Fairey
Re: Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 5, 2013 at 5:21:07 pm

Hi Craig,

Thanks for your quick response, and apologies for not noticing the sticky thread - it wasn't my intention to waste anyone's time.

The video plays back with no issues on all Mac machines I have tested it on - these have 10.6.8 and 10.7.4 (Snow Leopard and Lion). I have also tried it on two Windows laptops, both running Windows 7 version 6.1, this is where it fails to play back the audio for the first interview shot. It also fails to play the audio for the shot on an iPhone 4S running iOS 5 and on a Samsung Galaxy S2 running Android 4.0.4.

I have been using Final Cut Pro 7.0.3 and tried exporting in the following formats:

MP4 - H.264 codec, audio format AAC-LC (data rate 256 kbps, stereo 44.1kHz)
MOV - H.264, ProRes, each with 44.1kHz audio, Format: Integer (Little Endian), 16 bit sample size stereo.
AVI - Cinepak compression, audio uncompressed at 44.1kHz (picture looks shitty but at this point I was just seeing if anything would fix the audio - it didn't work).

Looking at the video in Windows Media Player, Quicktime, and on Youtube using Firefox and Chrome all produce the "missing audio" effect.

The file is to be played on a PC laptop, and possibly projected. It will also ultimately be put up on YouTube, but at the moment I am only using YouTube to show drafts to my client - the main focus is on getting a playable copy on a PC laptop.


Again, to reiterate - the audio is not present when played on PC machines and phone handsets, either from the hard drive of the machine or when viewed on YouTube. Plugging in a pair of headphones seems to magically fix the issue. I have tried compressing the audio separately, as a .aiff or .wav and then putting that into Final Cut so there is only one audio track but that hasn't had any effect. The video plays back without any problems in Final Cut also, and there are no filters on that audio region that aren't also implemented elsewhere in the video with no adverse effects - just light compression and a small amount of gain.

If anyone has any suggestions, I would be very grateful, and thanks again Craig for taking the time to respond.

Thanks,

Jon


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Craig Seeman
Re: Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 5, 2013 at 5:37:33 pm

As noted above. Audio is there for me on Windows 7 using IE9.

Tested on iPhone 5 iOS 6.1.2 and there's only music no voice on the first interview.

I don't think this is Mac OS vs Windows so much as you may have unmixed audio and some systems aren't playing both channels. Either that or you have phase cancelation specific to the voice on the first interview which would mean that something playing both channels would make the voice disappear.

I think you may need to remix the first spot and check stereo phasing. SoundTrackPro has a utility that displays stereo phase.



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Jonathan Fairey
Re: Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 5, 2013 at 5:48:23 pm

Hi Craig,

Thanks for your feedback. I will investigate and let you know how I get on.

Thanks again.

Jon


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Jonathan Fairey
Re: Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 6, 2013 at 10:21:36 am

Hi Craig,

Thanks for your advice - you hit the nail on the head. Soundtrack Pro flagged up problems with the phase of the audio. Fixing it in Soundtrack Pro has resolved the problem.

I am still not entirely sure how this occurred - the sound for that first interview clip was recorded using the same equipment, techniques and team as all of the other footage, and I'm still unclear as to why the phase issue seems to only affect certain machines - possibly the PC laptops I was testing it on just have one speaker, so the Macs are playing it back in stereo whereas other devices including phones are sending the stereo audio out through one speaker, which is where the problem arises?

Either way, I have fixed the problem now. Thanks Craig for your understanding and feedback (even though this turned out to not be a compression issue at all!). Hopefully this thread helps anyone else who has the same problem in the future.

Jon


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Craig Seeman
Re: Compression has resulted in audio that only plays back through headphones on non-Mac devices...!?
on Mar 6, 2013 at 5:46:21 pm

Two possible variations.
One is only one channel had the voice and it was the other channel being heard on some systems.
The other is one channel was out of phase with the other and caused cancelation when they were summed in the monitor on the computer.
Any number of ways either can happen and be missed depending on the monitoring system during production or post. It was a bit more common in analog days when cabling issues were one possible way to cause phase cancelation.



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