I have been looking at flac compression levels some more .Let me clarify uncompressed flac, since I confused flac 0 and uncompressed above.
Flac 0 is not uncompressed. It is the lowest level of flac compression, but it is still far from uncompressed. Many packages create flac 0, but dBpoweramp is the only one I know of that does truly uncompressed flac. There may be others, but dBpoweramp is the one I know.
As an example, I have a track that is 69KB (39%) at flac 6. It is 73 KB (42%) at flac 0 and 122KB with uncompressed flac. AIFF and WAV are also 122KB. So, if you want flac with no compression you need uncompressed flac, not flac 0.
Flac and WAV both have well defined meta-data capabilities. WAV
originally did not include meta-data, but many implementations do
include meta-data today, although the implementations can vary. So, if using meta data, flac and AIFF are the preferred formats.
Conclusion - If you want an uncompressed format use uncompressed flac (not flac 0), or AIFF, with WAV an option if you understanding the tagging issues.
The higher the compression level, the more compute time needed
to do the compression. However, people who understand the flac compression algorithms say
that the time to decompress the various
levels (0 to 8) are basically the same. That may not seem intuitive but
there are good explanations from the for the people who know. Uncompressed flac, however, should take not time to decompress, since it is not compressed.
Hope that helps clear up flac 0 and flac uncompressed. They are different.