[PROBLEM] Library update issues

[Leviathan]

Would welcome any help in resolving my issue.
Running a very simple set up - FLAC files stored on a USB stick, plugged into one of the USB 2 ports on my Pi4.
Issue is whenever I remove the USB stick to add more more music, I don't seem to be able to "remount" the USB stick so that all music is visible in the Library.
Latest example - today. Ripped CD to FLAC and copied to USB stick. Re inserted stick into the Pi and then tried both "update library" and then, Config/Library/Music database/Regenerate.
The new album does not appear under "Artists" or "Albums by Artists".
However, I know it's on the USB stick because if I navigate to Library/Folder/USB and then dig down through the file structure, I can both see and play the album.
I'm obviously doing something fundamentally wrong and would welcome any help.
Thanks

[Tim Curtis]

Very odd.

In tag view does the Genre or Artist named "Unknown" appear?

[Leviathan]

Hi Tim.
Looking at the screen now.
Under both Genre and Artist, I have "Unknown"
Under Genre, "unknown" lists several albums under "Albums by Artist". However, none of these are the album I copied today.
Under Artist, "unknown" lists just one album.
I am clearly doing something very wrong!

[Tim Curtis]

Try clearing the Library tag cache
Menu, Configure, Library

Also examine the MPD log to see if there are any errors related to the files.

cat /var/log/mpd/log

[Leviathan]

Thanks, Tim.
I did clear the Library tag cache earlier.
Will have a look at the MPD log.
In simple terms - and I do get very easily lost when trying to undertstand tags, etc - why do some albums end up under "unknown"? Is the answer simple or complicated?
Also, will an album stored under "unknown" still play if Moode/Pi is set to random play?
Thanks

[Tim Curtis]

Yes it should play.

Unknown means that particular tag is missing from the file.

[Leviathan]

Thank you Tim. Much appreciated.

[TheOldPresbyope]

@Leviathan 

Your ripper did apply at least a basic set of metadata values to the tracks in a Vorbis Comment tag, yes?

You can use the mediainfo utility from the command line to check the values. For example, here's the first stanza of the output for the Stereo Test file:

Code:

pi@moode3a:/mnt/SDCARD/Stereo Test $ mediainfo LRMonoPhase4.flac
General
Complete name                            : LRMonoPhase4.flac
Format                                   : FLAC
Format/Info                              : Free Lossless Audio Codec
File size                                : 2.02 MiB
Duration                                 : 38 s 761 ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 438 kb/s
Album                                    : Stereo Test
Album/Performer                          : Koz
Track name                               : LR Channel And Phase
Track name/Position                      : 1
Track name/Total                         : 1
Performer                                : Koz
Genre                                    : Utilities
Recorded date                            : 1997
Writing application                      : X Lossless Decoder 20161007
Cover                                    : Yes
Cover type                               : Cover (front)
Cover MIME                               : image/png
TITLESORT                                : LR Channel And Phase
ARTISTSORT                               : Koz
ALBUMSORT                                : Stereo Test
...

Regards,
Kent

PS - sometimes ripper/tagger apps mix up ID3v2 and Vorbis Comment tags on FLAC files. There should be only the latter. Easy test---use the file utility from the command line. Example:

Code:

pi@moode3a:/mnt/SDCARD/Stereo Test $ file LRMonoPhase4.flac
LRMonoPhase4.flac: FLAC audio bitstream data, 16 bit, stereo, 48 kHz, 1860560 samples

If that 4-character string "FLAC" doesn't appear at the beginning of the line for a FLAC file, then it's likely an ID3v2 tag has been added to the file whether a Vorbis Comment tag is also present or not. This is incorrect usage and can cause confusion.

ETA: PPS - I'm using "tag" in the strict sense of the container of the metadata key/value pairs and not in the sense of individual metadata key names.