Do you feel sometimes that you are cheated with a fake bitrate value? So audio files are presented as lossless o with a high bitrate and they are really just some low or medium bitrate files "saved as..."?
Your suspicion might be a "weird" sound quality. Your file is supposed to be a lossless FLAC and it sounds lousy. What to do? Checking the wave output on an app like GoldWave or Audacity won't give you any clue. Wave pattern for a lossless file or for a really poor 36 bps or are similar.
The solution is to use an audio file spectrum analyzer. Sounds "expensive" but it's actually just a freeware:
SPEK (IPA: /spɛk/, ‘bacon’ in Dutch) helps to analyse your audio files by showing their spectrogram. SPEK is a free software available for Unix, Windows and Mac OS X.
- Supports all popular lossy and lossless audio file formats thanks to the FFmpeg libraries.
- Ultra-fast signal processing, uses multiple threads to further speed up the analysis.
- Shows the codec name and the audio signal parameters.
- Allows to save the spectrogram as an image file.
- Drag-and-drop support; associates with common audio file formats.
- Auto-fitting time, frequency and spectral density rulers.
- Adjustable spectral density range.
- Translated into 19 languages.
Look for the version for your computer's OS: Windows, MAC or Linux. It's very easy to use and to interpret. Just load the file and watch the graphic output. Compare the output of a legitimate FLAC or WAV with a low bitrate copy of the same file. That's all, folks.
This is the the image from Spectrum Analizer for a 320 bps MP3 file
This is the image for real lossless FLAC file of same audio file
Actually, if you listen both with good quality but standard headphones, you can't appreciate any difference in quality
Note that sometimes the issue is with the original, Someone made a lossless rip from a bad quality vinyl. Well, in this case, no way, SPEK won't help you. My general advice: just trust your ears; if your audio doesn't sound fine it is not a good copy.