Stuart91 Posted May 27, 2011 Share Posted May 27, 2011 I'm relatively new to using QLab, and whilst it is fantastic I have discovered a strange glitch. WAV files which play fine within iTunes are distorting when played back in QLab. What happens is one channel peaks alarmingly. It isn't noticeably louder, but is clearly distorting the preamps on the desk. In the meantime, I have got around the problem by just using one side of the track. It is the same side which distorts, on two separate tracks. Play them back in iTunes, and the problem disappears. The best I can come up with myself is that there is some issue or incompatibility with the file format I'm using. The tracks were originally ripped into iTunes from a CD, and I had optimistically thought that they would carry over OK. QLab rejected a bunch of AAC format tracks so I suspect it might be fussy about such things. Wondering if anyone has come across a similar problem? Link to comment Share on other sites More sharing options...
rob.williams Posted May 27, 2011 Share Posted May 27, 2011 Have had the same problem and also importing WAV files into Logic. I found the easiest solution was to convert it to an MP3 in itunes. Everything worked fine then Hope that helps Link to comment Share on other sites More sharing options...
chelgrian Posted May 28, 2011 Share Posted May 28, 2011 The best I can come up with myself is that there is some issue or incompatibility with the file format I'm using. The tracks were originally ripped into iTunes from a CD, and I had optimistically thought that they would carry over OK. QLab rejected a bunch of AAC format tracks so I suspect it might be fussy about such things. Wondering if anyone has come across a similar problem? If you have 'sound check' on in iTunes the files may actually be broken and iTunes may be normalising them on the fly for you. The best thing to do is to see if they playback correctly using QuickLook in the Finder. If they do and they still don't play back correctly in QLab then it's worth sending them to Figure53 support along with your workspace to see if they can work out how they are broken. QLab will play m4a files but only non-DRMed ones. The most likely reason for Qlab to reject m4a files is they have been bought from the iTunes music store and thus are DRMed. Link to comment Share on other sites More sharing options...
Stuart91 Posted May 28, 2011 Author Share Posted May 28, 2011 Thanks for the replies. I'll try re-encoding as MP3s and see if that eliminates the problem. Unfortunately the tracks It would be nice to think that iTunes is correcting broken files, but I'll be very impressed if this is what it's doing. What I tend to see is momentary spikes on the meter on the affected channel, so there would need to be a very fast attack to avoid even moving the meters when iTunes is playing back. Will try quicklook in the Finder when I'm back in the venue tomorrow. The AAC / m4a files that QLab rejected were ripped straight from a CD into iTunes, so presumably DRM free? Link to comment Share on other sites More sharing options...
neilalexrose Posted May 28, 2011 Share Posted May 28, 2011 I'll try re-encoding as MP3s and see if that eliminates the problem. Unfortunately the tracks The only time I've ever had Qlab crash (albeit version 1) was when playing back an mp3 file and adjusting the volume during a tech. I personally wouldn't recommend using mp3 files at all for show purposes. I can see how it would appear to fix your problems, but it may cause other issues (from my own personal experience). Something to do with having to decode the compressed audio as well as playing at the same time - too many things to go wrong. I'm not sure what the answer to your problem is, but maybe opening the wav file in an audio editor (like audacity) will show you if there are any peaks/clipping/errors in the audio file. In audacity, you would also be able to re-save to different audio formats, rather than relying on iTunes. In my experience Qlab is pretty good at dealing with most audio and video formats. So these issues do surprise me. Also worth searching the Qlab list, and contacting figure 53 (as from what I hear they are pretty good with their support.) Neil Link to comment Share on other sites More sharing options...
Stuart91 Posted June 6, 2011 Author Share Posted June 6, 2011 Just to round this up, I didn't have too much of a chance to play with the files in the theatre, but haven't had any problems with other WAVs. Have reached the conclusion that it is just QLab being picky. Thanks to everyone for their help. Moral of the story - always check the tracks over before going live with them. At least I discovered the problem during a dress rehearsal and not an actual show. Link to comment Share on other sites More sharing options...
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