I have searched and (I think) followed suggestions from this forum on checking for corrupt files...
Ran all FLAC files through latest (still very old) version of AudioTester. Only 1 of almost 4k files failed. Then ran same files through dBpoweramp (test conversion) and got many failures; all were of type "Error reading metadata".
What confuses me is that none of the files that failed due to metadata (wth is that anyway?) would play in FooBar at all, but some would partially play in WinAmp though not starting at the song's beginning. Even more confusing to me is that every one that failed in either AudioTester or dBpoweramp's test conversion played just fine in VLC. Should clarify and say the 10 files I picked at random from the failed group all played fine.
How do I fix the metadata so I don't lose these files? Is it possible? I did convert (from within VLC) to FLAC and save to alternate location. Those played fine but not sure if they are true FLAC, not that I care at this point. I'm most interested in not losing the tunes altogether. Help please?
It is likely that these files not only have bad metadata but a bad initial flac header (it is just the metadata is one of the first items read).
Some other players use 3rd party flac decoders (I think Winamp and VLC) where as others such as dBpoweramp and foobar use official FLAC decoders, it could be one is better than the other with corrupted files. (I can only speak 100% for dbpoweramp, but think am correct about the others)
Why not use VLC to convert the files to WAV? Then you can use dBpoweramp to convert the WAV files to proper FLAC files. You'll have to re-tag them, but that shouldn't take too long if there aren't that many.
If you use mp3tag you can strip tags from files. I'm not sure about copying the metadata across in the mean time and writing it as proper tags?
Or you could try using flac.exe to re-encode the files. Using the force overwrite flag.
The resulting files should be a "freshly" encoded files. I suggest using the validate flag. And you could also use the opportunity to encode at a higher compression level (or any other you choose). Your files would also be updated to the latest version of FLAC.
Note that the headers are in fact copied across by default. Then you'll have a good hint as if the file is corrupted or the headers, etc. You could also use metaflac.exe to modify the headers.