Verifying Flac files

[Onclefritz]

In the last weeks, i copied all my flac files from dvds to hdd. I just did a analyze with Audiotester and i have 151 files failed. I have (LOST_SYNC @ 0m 00s), (FRAME_CRC_MISMATCH @ 0m 00s), (EXTRA SAMPLES) and (TRUNCATED @ 6m 20s) as errors. But 95% is (LOST_SYNC @ 0m 00s) errors.

What does this mean? Does these files are corrupted and have to go to the garbage? Does audiotester is a good program to check them? Do i have to check my flac files or its a waste of time if i have succeeded to copy them?

[M4ST3R M1K3]

I'm not familiar with audiotester then I don't know whether it's reliable (it might use an old libflac version and you get errors because some of your files were encoded with a more recent version). But if you suspect your dvds were damaged, audiotester is probable correct and your files are corrupted.

To verify my flac files I use:
the FLAC frontend, bundled with the latest FLAC (1.3.0)
or
Trader's Little Helper. It uses FLAC 1.2.1 but I think it changes nothing for verifying your files. Also it can verify your files using the MD5 hashes (of course if you files come with a .md5 file). For this, you can also use md5summer or a similar tool.

As I explained in another topic you can use some tools to try to recover damaged files from a cd or dvd. The ones I use, all free:
Recovery Toolbox for CD Free: It copies the good sectors and fills the bad ones with 0. It means the copied file has the same size than the original file, with some blanks inside. The drawback of this tool is that when the copy is done, it says "recovered" but it doesn't say if it successfully read the files after some retries or if it replaced the bad sectors with 0. Then you have to verify the files.
Unstoppable Copier: A tool I discovered recently. It's better in my opinion. You can tweak the speed (fast/weak recovery to slooooow/best recovery). And it says whether some sectors were unreadable (and how many, which ones in a log file). The difference with recovery toolbox is that it doesn't fill the bad sectors with 0 but don't write the bad parts to the output file. Then the copied file is shorter than the original. It's a different choice but I can't say it's better or not.

Finally if your files are corrupted and if you can't manage to get a good copy, you can try the "decode through errors" option of the flac frontend. Instead of stopping the decoding when it finds an error, it continues and tries to decode as much data as it can. Then your file may be playable but the bad samples. For example, I had a file that was very partially corrupted (99.5% was ok). It was the last track of the bootleg, and it was crowd noise. Well I decided to keep it like this, it's not very important you can't hear 1s of crowd.

[Onclefritz]

I have tried traders little helper and it gave me OS error during the scan. maybe a compatibility error. i have tried flac frontend but i prefer audiotester because it give me final report with the errors at the top. So if your scanning a lot of files, you dont have to scroll all the way to find them. Also it gives me the same errors as flac frontend.

[deadone]

yeah flac frontend bundled with flac tester

or you could try convert it to WAV and then back to flac again with foobar2000 and see if the error is still there.