Session changes playback speed

[jurld]

I keep having a really weird problem recently.

Over the course of the weekend I created a new 48k session. I imported a .wav file for a guide track, created several other audio tracks and tracked guitars. Then I created an instrument track, laid in some beats. Did some tempo mapping and then fooled around quite a bit with elastic audio. At some point I ditched the original .wav file.

All weekend, everything sounded "in tune" with my guitars, but felt a little slow to me.

At the end of yesterday I was feeling pretty happy, so I decided to bounce to disk so I could listen to what I'd done on the way to work this morning. I bounced and shut down Pro Tools.

I went to listen to the bounced track and it was sped/pitched up. Even more annoying, when I get back to PT, all the tracks are sped up there too. The pitch is off by about the same ratio as a 44.1/48k mismatch.

The speed of the bounced tracks (and now the session playback) is actually correct, when compared to the original guide track (I wasn't imagining it felt slow), but of course the pitch is too high.

PT is set to use the internal clock. I use an old Fast Track Pro interface with the latest drivers. It's little UI widget says it's set at 48k same as the session. I don't really think it's hardware. I'm pretty ignorant of how it all works though.

The wav file I used for the guide track is (ostensibly) 48k. I say ostensibly because that's what PT and Audacity says it is. It definitely started it's life several years ago as 44.1k when we created original tracks, and I'm not sure how I did any resampling to get it to 48k. Everything I look at says it's 48k though, and it sounds correct in PT and everything else I play it in.

It sounded fine (pitch was correct compared to my tuned guitar) when I was using it as a guide. I used tab-to-transient and beat identifier to arrive at 145 bpm and to set up the tempo map for the new session.

What I really don't understand is why 145 bpm would not always track at 145 bpm. I wish I could remember when it started feeling a little slow... but the pitch sounded "in tune" all weekend as I was layering guitar tracks so I chalked it up to imagination. I don't understand why bouncing to disk made EVERYTHING speed up once I restarted Pro Tools.

Most importantly, how the heck can I avoid this happening again? This isn't the first time stuff like this has happened recently. It is a new thing for me though. I recorded and mixed a 20 song album a year or so back and never had issues like this. I got burned out on that project and took some time away... Now it seems like every session I've started is doomed to end up this way. The first few times it was clear that the problem was a sample-rate mis-match with an imported audio file. It sounds like that is what is going on here again.

How can I be sure a 48k wav file is really 48k?

[jurld]

OK, it just did it again just now.

I cleared and deleted all audio files from the session, leaving just the midi drums.

I played through one take of one of the guitar tracks. It was pretty bad, so I started to do another take and was told that PT had lost contact with the Fast Track Pro. Saved session, exited Pro Tools. Restarted Pro Tools. When I set the audio track to record I heard a bunch of static.... exited Pro Tools. Restarted PC. Restarted Pro Tools. Set track to record and hit spacebar... Drums are now noticeably slower... I played several bars, and quit. Bounced to disk at this point. Yep, it plays back at correct speed but pitched too high, up to the point where I stopped... the original take I did still sounds OK.

I'm super confused now.

[jurld]

Ok. I have PT set to internal clock. I noticed that the HW control panel for the Fast Track Pro will still let me change its sample rate. If I change it to 44.1k, the playback in Pro Tools is slow. If I change it to 48k, it plays at normal speed.

I am going to guess my hardware does not always default to 48k, or something is causing it to drop to 44.1k at some point. I'll leave the control panel up when I'm recording to see if this is really what's going on.

[JuanPC]

In Windows, the Speaker icon, "next to the clock", playback properties, if are set to 44.1khz will not allow WindowsMediaPlayer to play other sample rate faster than selected...

If you have a session at 48k and bounce without Sample Rate Converter...
File speed will change when played at 44.1khz.

Most soundcards/WindowsMediaPlayer, will do SampleRateConversion if the soundcard clock is faster than audio file.

To avoid sample rate confusion,... Most people do not select/use the soundcard as Windows Audio Device...
They use the HDMI output of the video card... Or the on-board soundcard of the board...

I like using the soundcard...
No problem here.

[jurld]

The internal Realtek sound card is set to 48k.

I just don't understand why the Fast Track Pro hardware is not respecting the "internal clock" setting in Pro Tools, or vice versa.

The problem is pretty clear... sometimes the clock changes to 44.1... somehow. When I record with it that way and then bounce it bounces them at 48 and they are sped up. If the clock is at 48k, everything is fine.

Somebody I read suggested bad cables or dirty connections or ports might cause these sorts of problems.

[The Weed]

To be clear: Make your onboard soundcard the default for Windows sounds/audio and leave the Fast Track Pro for Pro Tools only. If you have a video card with HDMI, disable the audio portion in Device Manager.

[jurld]

On-board sound is the Windows default. I'll have to double check the HDMI video. The Fast Track is only used for Pro Tools as far as I can tell.

[jurld]

Yesterday evening I started up PT. Things sounded correct speed on playback, but when I enabled a track to record I only got hiss which pegged the meter. Shut down PT, rebooted PC. Went back to PT... looking at the control panel for the Fast Track Pro it shows 48k. Started recording... it's too slow. Used the control panel and set the FTP to 44.1.. Started recording... still too slow. Set the FTP back to 48k... and the speed was correct again. Recorded some tracks and bounced to disk. Everything was fine.

I'm going to chalk this up to potentially jacked-up hardware and/or drivers.

Thanks to those who replied.