(06-03-2021, 10:05 PM)DRONE7 Wrote: Put the USB drive back in your MAC...check the files are there then make sure you safely/properly remove it.
Then plug it back into the Pi...try another USB port (and not the USB3 ports)
Check that it us found...you can run  from a terminal if needed .

Code:

lsusb

Go to the library tab and do a full regenerate.

(06-04-2021, 12:11 AM)Tim Curtis Wrote: Feel free to zip up the album folder and PM a download link me and @TheOldPresbyope. One of us will analyze it when we get a chance.

(06-04-2021, 02:23 PM)Tim Curtis Wrote: The m4a files in the download you provided definitely crash the thumbnail generator and also cause tons of errors in MPD log when playing. This suggests some sort of issue resulting from the way they were created/ripped.

Note that the iTunes M4A files that I have in my test collection, both in AAC and ALAC format work fine with thumbnail generator and MPD. No errors whatsoever. They were all created in iTunes or provided by users who created or downloaded them via iTunes.

Here's some analysis showing the various issues in the files you provided.

# Detail logging from thmcache.php showing no further logging after attempting to process Home.m4a. This indicates thmcache.php either hangs or crashes.

Code:

20210604 090114 thmcache: path: /var/lib/mpd/music/USB/VFAT128/Test_mixed/steve/Misc/08 Church Of Flames.mp3
20210604 090114 thmcache: path: /var/lib/mpd/music/USB/VFAT128/Test_mixed/the_bertrum/Julia-Sophie - 3/Julia-Sophie - -3 - 04 love let you down.flac
20210604 090114 thmcache: path: /var/lib/mpd/music/USB/VFAT128/Test_mixed/This Is Happening/09 Home.m4a
c^C

# Mediainfo output showing an "Other" block present in the file specifying RTP (streaming) codec involved.

Code:

pi@rp2:/media/VFAT128/Test_mixed/This Is Happening $ mediainfo 09\ Home.m4a
General
Complete name                            : 09 Home.m4a
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42 (mp42/isom)
File size                                : 19.8 MiB
Duration                                 : 7 min 53 s
Overall bit rate mode                    : Variable
Overall bit rate                         : 351 kb/s
Album                                    : This Is Happening
Album/Performer                          : LCD Soundsystem
Track name                               : Home
Track name/Position                      : 9
Track name/Total                         : 9
Performer                                : LCD Soundsystem
Genre                                    : Electronica/Dance
Recorded date                            : 2010
Encoded date                             : UTC 2010-03-29 19:53:19
Tagged date                              : UTC 2012-08-14 08:06:42
Writing application                      : iTunes v4.0, QuickTime 6.3
Cover                                    : Yes

Audio
ID                                       : 1
Format                                   : AAC LC
Format/Info                              : Advanced Audio Codec Low Complexity
Codec ID                                 : mp4a-40-2
Duration                                 : 7 min 53 s
Source duration                          : 7 min 53 s
Bit rate mode                            : Variable
Bit rate                                 : 316 kb/s
Maximum bit rate                         : 373 kb/s
Channel(s)                               : 2 channels
Channel layout                           : L R
Sampling rate                            : 44.1 kHz
Frame rate                               : 43.066 FPS (1024 SPF)
Compression mode                         : Lossy
Stream size                              : 17.8 MiB (90%)
Source stream size                       : 17.8 MiB (90%)
Language                                 : English
Encoded date                             : UTC 2010-03-29 19:53:19
Tagged date                              : UTC 2012-08-14 08:06:42

Other
ID                                       : 2
Type                                     : Hint
Format                                   : RTP
Codec ID                                 : rtp
Duration                                 : 7 min 53 s
Language                                 : English
Default                                  : No
Encoded date                             : UTC 2010-03-29 19:53:19
Tagged date                              : UTC 2010-03-29 19:53:20
Source duration                          : 473339
Source frame count                       : 20213
Source stream size                       : 1299136
Stream size                              : 1299136
Bit rate mode                            : VBR

# MPD log showing timescale error

Code:

pi@rp2:/media/VFAT128/Test_mixed/This Is Happening $ tail /var/log/mpd/log
Jun 04 08:55 : update: added USB/VFAT128/Test_mixed/This Is Happening/01 Dance Yrself Clean.m4a
Jun 04 09:04 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 0, timescale not set

# MPD verbose log showing tons of Decoding Timestamp (dts) issues

Code:

pi@rp2:/media/VFAT128/Test_mixed/This Is Happening $ mpc play
LCD Soundsystem - Dance Yrself Clean
[playing] #74/82   0:00/8:58 (0%)
volume:  0%   repeat: off   random: off   single: off   consume: off
pi@rp2:/media/VFAT128/Test_mixed/This Is Happening $ tail -f /var/log/mpd/log
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 1, sample 396, dts 11586757
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 0, sample 543, dts 12608435
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 1, sample 396, dts 11586757
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 0, sample 543, dts 12608435
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 1, sample 397, dts 11609977
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 0, sample 544, dts 12631655
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 1, sample 397, dts 11609977
Jun 04 09:07 : ffmpeg/mov,mp4,m4a,3gp,3g2,mj2: stream 0, sample 544, dts 12631655
.
.
.

You could try converting the files to FLAC or some other format using an appropriate utility and see if the issues go away.

-Tim

"I am in the process of re-converting the files that do not show the work art to FLAC: I will let you know how this goes "

(06-04-2021, 10:54 PM)Tim Curtis Wrote: @Miss Sissy Princess 
The FLAC specification looks quite complete to my eyes.
https://xiph.org/flac/format.html
https://xiph.org/vorbis/doc/v-comment.html

FLAC codec and associated utilities from xiph.org are IME the most widely used in Linux audio precisely because of their high quality implementations, efficient algorithms and well defined specifications.

ALAC is typically only found in collections where iTunes is or was used. Even after Apple released the ALAC specification back in 2011 as Open Source the adoption rate has been almost nil in the Linux audio community because FLAC has been in use since 2001 and was already a proven winner with high quality implementations, speed, efficiency and metadata support.

Oddly Apple still does not support FLAC in the iTunes / Apple Music eco system while most Linux audio players support a wide variety of formats including ALAC.