HELP! Audio distorted on playback

[mitodages]

Hello All!

I recorded a classical guitar recital this past weekend, and although the audio I was monitoring through my 896mk3 sounded excellent, now when I opened the session, I'm finding out that the audio was completely distorted and at a faster than normal speed! I recorded two concerts this past weekend, and the second one sounds completely fine.

I'm using DP 8.07 on an iMac running 10.10.3. Interface is a MOTU 896k3. Audio was recorded in DP7 on an older MacBook Pro running Lion.

Could it have been a loose firewire connection maybe? I don't know what else would cause the issue.

It looks like there is no hope for the audio as the WAV files themselves are presenting the issue, whether i play them back in DP or not.

How can I possibly avoid this in the future? Any and all insight is helpful!!!

[trex67]

I'm having this problem, too, but with 7.24. I recently bought a new iMac to replace my old one. I had to get a replacement CD to register so I only just started using DP again. On my first mix since the upgrade I noticed that what I was hearing during my mix wasn't what I got after the bounce to disc - I'm getting very heavy distortion and lots of "breathing" like it's over-compressed. I've gone over all the settings I can think of but the problem has persisted for a couple of days now. I'm getting pretty frustrated. I wondered if I just needed to upgrade to 8, but now I'm not so sure.

[Shooshie]

SOOOOO many possible answers.

Let's narrow it down. Give us the bit rate and sample rate of the recordings. Then look in the Soundbites window and see if the soundbites that are distorted are also of those same bit and sample rates. If not, then what are they?

Was everything recorded in DP? What version of DP? What version of the operating system? Are you running DP and plugins as 32 bit or 64 bit applications?

The distortion may not be from sample mismatch, but from overstating the volume. Check the chain of connections, settings, knobs, buttons, sliders, plugins, and so forth, and see if there is any point where the audio is getting a significant boost.

If it's just the bit/sample rate mismatch, you can probably fix that by converting it, following carefully the options in the dialog that comes up before you do. One of the options will let the pitch go back to where it should be at the project's sample rate.

Meanwhile, there are just too many possible user errors for us to zero in on any of them at this time. Maybe after you do a complete and thorough examination of the audio path from input to output, you'll be able to tell us more about the problem, and maybe the fix will suggest itself..

Shooshie

[Shooshie]

I'm having this problem, too, but with 7.24. I recently bought a new iMac to replace my old one. I had to get a replacement CD to register so I only just started using DP again. On my first mix since the upgrade I noticed that what I was hearing during my mix wasn't what I got after the bounce to disc - I'm getting very heavy distortion and lots of "breathing" like it's over-compressed. I've gone over all the settings I can think of but the problem has persisted for a couple of days now. I'm getting pretty frustrated. I wondered if I just needed to upgrade to 8, but now I'm not so sure.

I assure you, the problem is user error. Upgrading will not fix the problem, unless you've got a very unusual situation that we rarely encounter. But we cannot tell you what the error is unless you do what I advised the original poster in my previous message.

It can happen to anyone, but you have to track it down with a bloodhound's nose for detail.

Shooshie

[mitodages]

My issue is definitely not gain related, and isn't a DP playback issue either, as the WAV files themselves are displaying the issues, which are clipped and sound twice the speed they should be.

All my versions that I was using were in my first post. I was recording only in DP, no plugins, at 24/96 29.97 non drop.

This has popped up for me before, where I stop a recording, listen back and hear that the audio is corrupted, and end up restarting the Macbook Pro and when I open DP again, the issue is gone.

Just want to try and avoid this in the future, and was hoping to narrow down the reasons for it. I initially thought maybe it was a loose firewire connection or something. I recorded another recital the very next day, and that came out wonderfully.

[HCMarkus]

Diagnosing intermittent or one-time issues is very challenging. The speed issue sounds like a clock mismatch; where 48k files are being played back at 96k rate, but I can't explain the amplitude issue, other than a possible resolution error, where DP thinks the 24 bit files are 16 bit. I have been recording with DP for years and have only experienced the clock issue when using external clocking, and due to human error.

A clock mismatch is easy to create if using an external clock, but the MOTU hardware is supposed to automatically conform to the rate set within DP. In the hopes that you might notice a discrepancy before you have another disaster, I would consider carefully noting the sample rate displayed on your interface when preparing to record and making sure it matches the rate set in DP.

As Shooshie noted, the are tools within DP that will allow you to change the header on audio files without actually re-writing the files. I would experiment to see if you can get your corrupted audio files to play at the proper speed and amplitude. The tools can, if I recall correctly (not at DP at the moment), are accessed from the soundbites mini-menu. I have used these tools to successfully restore files with clock mismatch on several occasions.

Good luck!

[mitodages]

Going through the audio now, and now that I look at it again, the length of the file within DP is 34 minutes, when the recital was easily an hour long or more. I took the file and stretched it out to double its length, and now the audio is at the correct speed, but sounds as if the audio is passing through a ring modulator almost. Although now the speed of the file is correct, I don't know what I would do to remove the distorted elements from the sound. Perhaps it was indeed a clocking mismatch between DP and my 896mkIII.

[HCMarkus]

Don't time stretch! Change the header as I mentioned.

[Timeline]

DP's set SR does get out of sync occasionally when files do not conform to standard SR's due to lost connections or something. I have used non standard SRs like 127 SR and found the sync eventually fails. Not that you could even do that with a MOTU IO but possibly the DP identifying switch between the IO and DP software was lost. I once recorded a High school band and when I got home the files were at the wrong speed although it claimed 48k 24bit. I had to use the variable speed control in my RME to match the proper speed / pitch and when completed worked it out but RME was the variable clock at that point and had a cool software handle to re-insert the sync somehow at a slower speed. All very strange but it does happen once in a while. Distortion means it really got far far off.

[mitodages]

Hello gents, so in DP you change the header by selecting the audio in the soundbites window and choosing "convert audio file" correct? So i was recording at 24/96, and thats what the file says as well. Since the audio is basically twice as fast as well as distorted, how should I set the conversion?

In other news, I had another two gigs this weekend, the first went flawlessly, and at the next one, my portable hard drive disconnected itself. Perhaps the root of my issues is a failing hard drive. Or could something have happened within DP to cause such an issue. Luckily I had my backup recorder going, as I lost the first two songs when the hard drive disconnected.

I then continued recording right to my MBP hard drive. Perhaps I'll invest in a new SSD if my hard drive is the issue, which may be the case as it is a nearly 7 year old Lacie rugged drive.

BTW, I really appreciate all the help I've received so far. I pride myself on being very careful and meticulous in my work to prevent such errors, so this is not something I'm used to!

[HCMarkus]

Hello gents, so in DP you change the header by selecting the audio in the soundbites window and choosing "convert audio file" correct? So i was recording at 24/96, and thats what the file says as well. Since the audio is basically twice as fast as well as distorted, how should I set the conversion?

Set the header to 48k (check "Only change the file's recognized sample rate but do not process the file's audio") and play back in a project at 48k clock rate in DP. If my brain is working right, you should hear playback at proper speed.

Not sure about the distortion part though. Try Bite Gain.

[mitodages]

Set the header to 48k (check "Only change the file's recognized sample rate but do not process the file's audio") and play back in a project at 48k clock rate in DP. If my brain is working right, you should hear playback at proper speed.

Not sure about the distortion part though. Try Bite Gain.

Alrighty, so I went ahead and did this, and it went from sounding twice as fast, to normal speed, but the audio sounds like it it pitch shifted lower by several octaves. And the file still has the digital distortion happening as well throughout.

If I can get it to the correct pitch it would be great, but I still would probably have that distortion in there, but I may be able to clean that up possibly. It has a static like sound to it and is constant, but gets louder with the audio.

[David Polich]

You know what this sounds like (no pun intended) to me - your audio interface drivers went out to lunch when you were actually recording. I've had this happen a couple of times in the past. The solution, sadly, was just to ditch what was recorded because frankly, it was hosed beyond repair.

What causes drivers to go AWOL? I have no idea. Restarting usually fixes things, but it won't
resurrect the audio you recorded.

[HCMarkus]

What Dave said. Unfortunately most likely the sad truth.

As I noted before, in the hopes that you might notice a discrepancy before you have another disaster, I would consider carefully noting the sample rate displayed on your interface when preparing to record and making sure it matches the rate set in DP.

And do a short test recording before each session.

[mitodages]

I think you guys are right. I've had this issue before where i start recording, sounds great in the headphones monitored through my 896, and then when I stop and listened back to the short bit I just recorded, it sounds exactly like what I just experienced. Then I would restart everything and it would put it back all hunky dory.

I always do a short test recording for this reason, but I think my mind went out to lunch along with the drivers, because I must have skipped it this time. Of course.

Thanks for all the help everyone. Just have to chalk it up to a lesson learned.