Rockbox Technical Forums

Support and General Use => Recording => Topic started by: gsh on December 15, 2006, 07:43:04 AM

Title: Wav files suddenly gone silent?
Post by: gsh on December 15, 2006, 07:43:04 AM
I'm posting this in behalf of my technologically challenged friend, so bare with me.
He has just recorded a few wav files via line in on his H120 (concerts). He had listened to 2 of them via the headphones to check them, and all seemed well. When he's tried to copy them to his harddrive they are all silent. They show as playing and show the correct filesize for the duration, but no sound.
He tried both on his pc and iriver, same result.
A couple of test wav recordings he made a few days prior are still playing ok.
Is there any chance of being able to recover/repair the files? I talked him through chkdsk /f and that doesn't appear to have worked.
He is uploading one of the smaller files for me to test/try and fix.
Any help will be greatly appreciated.
Title: Re: Wav files suddenly gone silent?
Post by: Raptor on December 15, 2006, 01:50:34 PM
I think I ran into the same thing before on one of the files I had recorded with Rockbox.  I don't know what caused the problem to emerge... I could play the file on my H120 but I couldn't play it on the computer.  I figure it has something to do with the headers in the audio file.

The solution I found was to download Audacity (it's free: http://audacity.sourceforge.net/) or any other capable audio program that can import Raw Data.  In Audacity, you can find this option under Project > Import Raw Data...  From there, just use File > Export As... to save the audio to whatever format you prefer.

Hope this helps.
Title: Re: Wav files suddenly gone silent?
Post by: gsh on December 15, 2006, 05:54:51 PM
Thanks, but I've tried this already with the smaller file he sent me to no avail. If he hadn't already listened to them I would have said it was user error or the battery box battery dired, but he insists he listened to parts of 2 of the now silent files. I'm totally stumped.
Title: Re: Wav files suddenly gone silent?
Post by: Llorean on December 15, 2006, 06:10:07 PM
You said the copied files don't work. Do the originals still work?
Title: Re: Wav files suddenly gone silent?
Post by: petur on December 15, 2006, 06:13:00 PM
If you opened the file in audacity, was it really all silence or maybe very low signal?

Anyway, I cannot beleive that all the data in a file can go blank and the header stay ok.
Title: Re: Wav files suddenly gone silent?
Post by: jhMikeS on December 15, 2006, 06:31:04 PM
 ???  :o

Would love to have a copy of a file that exhibited this behavior and examine the header and verify it and the data itself. Would need the whole thing to check that exactly as many bytes are there as the header says there should be amongst other things.
Title: Re: Wav files suddenly gone silent?
Post by: gsh on December 16, 2006, 09:56:30 AM
Here are links to one of the smaller test recordings - as it's over 100mb he used winrar to split it into 2 files of 100mb + 50mb (no compression, archive only)
http://rapidshare.com/files/7602730/rec_0005.part1.rar.html
http://rapidshare.com/files/7590701/rec_0005.part2.rar.html

Thanks - this is very strange!
Title: Re: Wav files suddenly gone silent?
Post by: jhMikeS on December 16, 2006, 05:18:22 PM
On first inspection it doesn't even look like audio data but duration and such look good. It starts off with a bunch of samples of value 2 and 3 and then I see only 0 and -1 after that for the most part so it looks pretty silent. I normalized the recording and can indeed hear faint audio in the noise. About every 2:50 there is a little spike in the levels...probably low-level noise from a disk flush. Almost looks like a wrong input selected.

If the peakmeters were active and showing good levels during the recording, the data was coming in for sure and it sounds like the data is there with extreme attenuation. If any part of this could ever be played on the device and listened to with normal audible level, recording couldn't be at fault since it's no longer active after it is stopped.

Like petur said, it's a rather odd notion that the headers would be ok (it is) and only the samples attenuated much less by a file copy. I've copied files over 2h off my player without incident.

Attached is a sample of what I got out of it after much processing. (Rename extension to "mp3")

[attachment deleted by admin]
Title: Re: Wav files suddenly gone silent?
Post by: gsh on December 17, 2006, 05:09:47 AM
Thanks for investigating. I figured it was a longshot that they could be recovered.