After spending around 6 months on and off encoding CDs to FLAC, I have started to actually listen to some of my efforts, and to my horror, around 1 in every 20 FLAC files have errors in them, to the extent that they won't enven decode back to WAV. Is there an app I can use to check all my FLAC files at once, to ascertain which ones have errors in them? I've been usiing FLAC front-end to encode from WAV. At first, I thought the problem was isolated to FLAC files I had encoded, but errors have appeared in live recordings that I downloaded (in FLAC format). What could have happened here?

At the moment, the only way I know of to check for FLAC errors, is to do a search for all FLAC files, drag the results to WinAmp, press play, and wait for WinAmp to stop and report an error for each track with errors in it. Suffice it to say, this will take forever, so any help here would be much appreciated.

This thread has some options.

The FLAC Tester and OGG Tester apps were just what I've been looking for. Many thanks. I don't suppose you know of anything for APE and MP3?

APE has a built-in check feature in the command-line app. Type:

MAC "<filename>" -v

I'm assuming you are using Windows. You can get the command-line version of APE here if you don't have it already.

My batch file ape-verify.bat may be useful - or use the Monkey's Audio GUI.

My website has a little more info.

I am not sure what the general view is on Encspot as I dont use MP3 but it will give you detailed info about your Mp3s including errors.

Encspot

Not only does the Monkey's Audio gui have a verification function, but Monkey's Audio files, by default, include built-in CRCs, and I'm not sure if FLAC includes those or not. You can check a file all you want, but having built in CRCs will certainly make the file verification more accurate. I also archive my APE files in WinRAR and I make sure to check 'add recovery record' for extra protection

Also, do you use Exact Audio Copy or some other grabber? Is your drive C2 capable? Some of the audio errors you're encountering could be from the original rip. The errors in the FLAC files themselves may be indicative of a hard drive issue, you might want to test your drive...

did you encode them with -V (--verify) ? if so did they all verify OK?

Josh

FLAC uses MD5SUM signature for integrity test. This is a 128 bit long checksum. You do not need more to have a piece of mind. Also when you encode use the --verify option.

Triza (FLAC enthusiast)

That's really good to know thanks!

Yes, I used the Verify option when encoding all my FLAC files, and no errors were ever reported. I'm fairly certain some of my files have become corrupt after encoding - a result (I think) of the RAID card failing.

Anyway, I ran FLAC Tester and it reported 83 files with errors in out of 1600+. It's not a total disaster, but it's time I don't really relish having to go through again.

Here are a selection of some of the errors reported by FLAC Tester:

FLAC__STREAM_DECODER_UNPARSEABLE_STREAM
ERROR_FRAME_CRC_MISMATCH @ 3m 45s
ERROR_LOST_SYNC @ 1m 42s

Thanks, I'll give that a try.

Something Spooky

I had the same errors some months ago, asked here and did a lot of tests which led to that I no longer use Flac.

Had to redo about 50 vinyl rips (Out of 1000+) and archive in Wav instead.

I want to trust Flac, but I haven't find the reason why it fails. (I used the -V switch etc.)

I have only tried encoding on AMD XP computers. Is there a general incompability with AMD XP??

You are shooting the messenger.

I use flac on Linux and Windows and never had any problems barring one case. Even that one was a HW error. It was a faulty USB PCMCIA card. When I had it plugged in it corrupted my data. Memory issues are known to cause similar symptoms. You have memory issues or some other HW error. So far I heard a number or reports like this and every time it was followed up it turned out to be a HW bug.

You might not like Flac, but due to your very likely HW issues, I would not trust your PC, especially not for long term archiving. It is just that FLAC has a lot of internal tests not just at encoding, but at decoding as well unlike a WAV file, so you can catch these issues. You should be very thankful for that instead of bashing the format that is the most popular lossless format. If it would not work universally it would not be popular.

Triza

I'm not bashing..
I found flac to be the superior format.. until I noticed the errors.
I have tried everything suggested here, memtest etc.
It might be my computer
I'm just so confused , everything else works perfect...

I will try 1000 files on my new Pentium Laptop an see if it works

depends, what motherboard is it? there have been reports (not just FLAC, other programs too) of problems with some specific motherboards (e.g. ASUS A7V133). see also
http://flac.sourceforge.net/faq.html#tools__hardware_prob

with WAV there is no error checking. you won't discover the problem until you're listening to it.

Josh

Just an Update

I've had the errors on 3 different AMD computers.
1. MB Epox, Chipset Via CPU AMD XP 2500
2. MB MSI, Chipset nForce2 CPU AMD XP 2500
3. MB ASUS, Chipset VIA CPU AMD 2600 (Sempron)

No problem with Memtest on these Computers
The first configuration gives similar errors also with Ape compression!
All the above configurations works with Wma lossless.

Flac works on my Pentium 4 Laptop.

Changed the first machine to a Pentium 4 630 and a new MB today. Will run some heavy tests on that machine.