Waveform shows up as straight line

I’ve been using ELAN (started with 4.2, using 4.5 now) on my MacBook running OSX 10.7.4 without any problems, but yesterday a new problem showed up. The .wav files that I link to my .eaf projects show up as a straight line, though the sound is fine. When I increase the vertical zoom to 3000% there is something that shows up but it looks like a faint static with no variation.

My process is this: I convert .mts files to .mp4 files of about half the size using Wondershare Video Converter, then extract and convert the audio from the .mp4 file to .wav using Audacity. This has always worked fine until now

It gets weirder. When I open the same .wav in Audacity, it shows up as a normal .wav form. And, weirder still, if create a new .eaf with ONLY the .wav file, it shows up normally, however if I update, or remove then re-link the .wav in the original .eaf file, it remains as a straight line.

Weirder yet: I managed to get the waveform to show up as normal by creating a new .eaf with just the .wav file, then later adding the video file and .etf template. It seemed fine, but when I closed and opened it again I got this message:

“WARNING
No player could be created for:
-file:///Users/joshua/Documents/UM/Fieldword/Interviews/MARCO.etf
The Cocoa QT Player can not handle this file.
Could not initialize class quicktime.QTSession”

however, the waveform appeared as normal and everything seemed to be fine… until I noticed that at about 6 minutes into the 12 minute file, the waveform suddenly turned to a straight line once again. When I closed the file and opened it again, the whole waveform was once again a straight line.

If anyone has any idea what is happening hear, I would greatly appreciate it, as it is a puzzle I cannot solve.

Many thanks in advance for your kind help.

Joshua Shapero
University of Michigan

Update: I was messing around with this and discovered that the problem is resolved if I use stereo waveform view. The line disappears if I use merged, and returns if I go back to stereo. Any ideas about this bug? It is only happening on files I created since the 18th of February… ???

I’ve no immediate explanation, but the bug seems to be related to the format of the wav file. If you could make availabe one (short) wav file that “disappears” in merged or blended mode, then we could have a closer look (han.sloetjes AT mpi.nl).

-Han