bash-flac-diag

This is a simple bash script for Linux to test FLAC audio files recursively and generate logs with good files (no errors found) and bad ones (at least one error found). The script tests flac files with the help of flac cli encoder/decoder, which detects errors in the stream and when

the MD5 signature of the decoded audio does not match the stored MD5 signature, even when the bitstream is valid.

This tool is meant to be used to identify corrupted flac files that should be deleted from an audio library, for example. Here's a demo of it:

Requisites

• flac cli. Most distributions have a flac package.

• Standard Linux packages. (If you're running a mainstream distro, you don't need to worry about installing any one of them.)

When running flac_diag.sh, the script will attempt to detect all necessary programs and if there's one missing, you'll see a message about it. Make sure that if they're installed, they're also in your user's $PATH.

Installation

I've only tested this script with Debian and Ubuntu but it probably works just fine with any other standard Linux distro.

Debian/Ubuntu

• Via git

sudo apt update
sudo apt install git -yy
cd /opt
sudo git clone https://github.com/cgomesu/bash-flac-diag.git
sudo chmod +x bash-flac-diag/ -R
cd bash-flac-diag/
./install.sh

• Via github cli

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key C99B11DEB97541F0
sudo apt-add-repository https://cli.github.com/packages
sudo apt update
sudo apt install gh
cd /opt
sudo gh repo clone cgomesu/bash-flac-diag
sudo chmod +x bash-flac-diag/ -R
cd bash-flac-diag/
./install.sh

Usage

To scan and test all flac files inside a music folder recursively, simply run the script adding the /full/path/to/music/folder/ as argument, as follows:

./flac_diag.sh /path/to/music/folder/

or

bash flac_diag.sh /path/to/music/folder/

The script will create a ./log subfolder with two log files, namely bad_flacs.log and good_flacs.log. The former has a list with the path of each .flac file that has produced at least a single error when running the flac utility in test mode, while the latter has a list with the path of each .flac file that has not produced any errors. A detailed description of all errors produced by each file are stored on ./log/errors/ for debugging.

(Optional: If you wish to create a log file with the output of the flac_diag.sh script, you can simply redirect the output to a file of your preference. For example, to output to a file called output-10-06-2020.log, simply run bash flac_diag.sh /path/to/music/folder/ > output-10-06-2020.log.)

In most cases, after testing all .flac files, you'd want to:

1. Double check a few files in bad_flacs.log, to make sure they are actually corrupted;
2. Make a backup of the current bad_flacs.log files;
3. Attempt to fix the files in bad_flacs.log by re-enconding them; then manually recheck the files or clean the bad_flacs.log and re-run the flac_diag.sh script;
4. Then if re-encoding doesn't work as expected, remove all files in bad_flacs.log from your music folder.

Fixing bad flac files

To attemp to fix the bad .flac files, you can use a tool in the ./tools subfolder called bad_flac_fixer.sh, which takes a bad_flacs.log as argument and overwrites every single file listed in there with a re-encoded version of it. To fix all files listed in ./log/bad_flacs.log, run the following from the git root folder:

./tools/bad_flac_fixer.sh log/bad_flacs.log or bash tools/bad_flac_fixer.sh log/bad_flacs.log

Make a backup of your bad_flacs.log, delete/clean the old ./log/bad_flacs.log, and re-run the flac_diag.sh script. If the errors persist, I suggest to remove the bad files.

Removing bad flac files

To remove the bad .flac files, you can use a tool in the ./tools subfolder called bad_flac_remover.sh, which takes a bad_flacs.log as argument and deletes every single file listed in there. To delete all files listed in ./log/bad_flacs.log, run the following from the git root folder:

./tools/bad_flac_remover.sh log/bad_flacs.log or bash tools/bad_flac_remover.sh log/bad_flacs.log