Each of these parts has a location in the file, a length and other information that helps software go directly to the correct part of the file… a bit like a map. So a FLAC file is broken down into many different parts. Importantly, it is written to contain different types of data as well, such as metadata which we use for good stuff like embedding cover art. What do I mean by structural problems? Well, FLAC is a container format which means it contains more than just audio. If you’re uncomfortable with the command line and on Windows, give the FLAC frontend a try. The resulting checksum includes the audio problem, and so the checksum comparison works fine - software should no longer complain.Īfter re-encoding you’ll have a new file, fixed.flac, which should not complain when played. This means, if there’s some (inaudible) audio artifact, this is treated as the original audio and so FLAC error checking via a checksum is ‘reset’ to allow the original problem. What this does is use the original FLAC as input. Replace corrupted.flac with the original FLAC file name. ![]() The command line to do this is: flac -verify -decode-through-errors -preserve-modtime -o fixed.flac corrupted.flac If you don’t, and you’re happy to live with a suspected unfaithful reproduction of the original music, you can simply re-encode the FLAC file.īut beware, you might be storing up problems - what if you get a better hi-fi in a few years where you can hear the difference? Re-encoding a FLAC If you do have to hand the original music it’s probably best to re-encode, as above. If you don’t notice an audio problem, things are a bit more subjective. WAV files you can encode from them without any nasty physical spinning discs. For example, you’ll need to re-rip a CD and re-encode with flac. ![]() To get back to a byte-for-byte faithful reproduction of the original music you will need the original music. If you notice a problem in the audio, then it’s most likely you’ve got an unrecoverable problem. ![]() Fixing FLAC audio corruptionĬorruption related to the audio stream is often the most difficult to fix. FLAC_STREAM_DECODER_ERROR_STATUS_FRAME_CRC_MISMATCH One of the best aspects of FLAC is internal error detection - this means the error checking found the audio did not match what was originally encoded. FLAC_STREAM_DECODER_ERROR_STATUS_BAD_HEADER More specific than the previous error, this happens when the audio data has a frame header (which gives information about the audio, e.g. It can be caused by badly structured data inside the FLAC file, corrupted audio within a frame within a FLAC file, or many other reasons. Some common FLAC error messages include: FLAC_STREAM_DECODER_ERROR_STATUS_LOST_SYNC The most common error this means the software was unable to read the file correctly. In the real world, though, the first time you’ll know you have a corrupt FLAC is when you try to play it, and you get a nasty error message. Ideally you’d proactively check your FLACs for corruption. ![]() Both are important even though any given music player might be able to play the audio from a structurally-corrupt FLAC file it doesn’t mean other tools will be able to work with the files when different operations are performed, such as tagging. There are two main types of FLAC corruption: those that exist in the audio stream and those in the overall structure of the file. It’s impossible to repair all FLAC problems. Well I’ve got some good news and some bad news. Unfortunately I left the post on a bit of a cliff-hanger… once you’ve found some corrupted files, what do you do about them? Back in 2015 I wrote a popular post about finding corrupt FLAC files.
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