Peview Generator refueses to make thumbnails for videos from Samsung (any android version) phones

[yoGhurrt1]

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Steps to reproduce

1. Record any video with Samsung
2. Upload it to Nextcloud
3. No profit - go to Memories app and not get any thumbnail for uploaded video. Of course this video can be played without any problem in Nextcloud, it’s just a problem with thumbnail.

Expected behaviour

Preview Generator should generate thumbnail for requested file

Actual behaviour

sudo -u www-data php occ preview:generate /directory/filename.mp4 -vvv

In Generator.php line 366:

  [OCP\Files\NotFoundException]
  No provider successfully handled the preview generation


Exception trace:
  at /var/www/nextcloud/lib/private/Preview/Generator.php:366
 OC\Preview\Generator->generateProviderPreview() at /var/www/nextcloud/lib/private/Preview/Generator.php:313
 OC\Preview\Generator->getMaxPreview() at /var/www/nextcloud/lib/private/Preview/Generator.php:117
 OC\Preview\Generator->generatePreviews() at /var/www/nextcloud/lib/private/PreviewManager.php:182
 OC\PreviewManager->generatePreviews() at /var/www/nextcloud/core/Command/Preview/Generate.php:92
 OC\Core\Command\Preview\Generate->execute() at /var/www/nextcloud/3rdparty/symfony/console/Command/Command.php:326
 Symfony\Component\Console\Command\Command->run() at /var/www/nextcloud/3rdparty/symfony/console/Application.php:1078
 Symfony\Component\Console\Application->doRunCommand() at /var/www/nextcloud/3rdparty/symfony/console/Application.php:324
 Symfony\Component\Console\Application->doRun() at /var/www/nextcloud/3rdparty/symfony/console/Application.php:175
 Symfony\Component\Console\Application->run() at /var/www/nextcloud/lib/private/Console/Application.php:187
 OC\Console\Application->run() at /var/www/nextcloud/console.php:87
 require_once() at /var/www/nextcloud/occ:33

preview:generate [-s|--size SIZE] [-c|--crop] [-m|--mode MODE] [--] <file>

Server configuration

Web server: Apache 2.4.58

Database: MariaDB

PHP version: 8.3

Nextcloud version: 31.0.5

List of activated apps

Enabled:
  - activity: 4.0.0
  - app_api: 5.0.2
  - bruteforcesettings: 4.0.0
  - circles: 31.0.0
  - cloud_federation_api: 1.14.0
  - comments: 1.21.0
  - dashboard: 7.11.0
  - dav: 1.33.0
  - federatedfilesharing: 1.21.0
  - federation: 1.21.0
  - files: 2.3.1
  - files_downloadlimit: 4.0.0
  - files_external: 1.23.0
  - files_pdfviewer: 4.0.0
  - files_reminders: 1.4.0
  - files_sharing: 1.23.1
  - files_trashbin: 1.21.0
  - files_versions: 1.24.0
  - firstrunwizard: 4.0.0
  - ldap_write_support: 1.13.0
  - logreader: 4.0.0
  - lookup_server_connector: 1.19.0
  - memories: 7.5.2
  - nextcloud_announcements: 3.0.0
  - notifications: 4.0.0
  - oauth2: 1.19.1
  - password_policy: 3.0.0
  - photos: 4.0.0-dev.1
  - previewgenerator: 5.8.0
  - privacy: 3.0.0
  - profile: 1.0.0
  - provisioning_api: 1.21.0
  - recommendations: 4.0.0
  - related_resources: 2.0.0
  - serverinfo: 3.0.0
  - settings: 1.14.0
  - survey_client: 3.0.0
  - suspicious_login: 9.0.1
  - systemtags: 1.21.1
  - text: 5.0.0
  - theming: 2.6.1
  - theming_customcss: 1.18.0
  - twofactor_backupcodes: 1.20.0
  - updatenotification: 1.21.0
  - user_ldap: 1.22.0
  - viewer: 4.0.0
  - webhook_listeners: 1.2.0
  - workflow_media_converter: 1.13.5
  - workflowengine: 2.13.0
Disabled:
  - admin_audit: 1.21.0
  - contactsinteraction: 1.12.0 (installed 1.9.0)
  - encryption: 2.19.0
  - files_rightclick: 0.15.1 (installed 0.15.1)
  - files_scripts: 4.1.0 (installed 4.0.3)
  - sharebymail: 1.21.0 (installed 1.18.0)
  - support: 3.0.0 (installed 1.11.0)
  - twofactor_nextcloud_notification: 5.0.0
  - twofactor_totp: 13.0.0-dev.0
  - user_status: 1.11.0 (installed 1.8.1)
  - video_converter: 1.0.6 (installed 1.0.6)
  - weather_status: 1.11.0 (installed 1.8.0)
  - workflow_script: 2.0.0 (installed 2.0.0)

Nextcloud configuration

{
    "system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "nc.p12.com.pl",
            "192.168.1.112"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "31.0.5.1",
        "overwrite.cli.url": "https:\/\/192.168.1.112",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "mysql.utf8mb4": true,
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "maintenance": false,
        "ldapProviderFactory": "OCA\\User_LDAP\\LDAPProviderFactory",
        "theme": "",
        "loglevel": 2,
        "twofactor_enforced": "false",
        "twofactor_enforced_groups": [],
        "twofactor_enforced_excluded_groups": [],
        "defaultapp": "memories,files,dashboard",
        "memories.exiftool": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/exiftool-amd64-glibc",
        "memories.vod.path": "\/var\/www\/nextcloud\/apps\/memories\/bin-ext\/go-vod-amd64",
        "enable_previews": true,
        "enabledPreviewProviders": [
            "OC\\Preview\\Movie",
            "OC\\Preview\\TIFF",
            "OC\\Preview\\Image",
            "OC\\Preview\\HEIC"
        ],
        "preview_max_memory": 5120,
        "skeletondirectory": "",
        "memories.vod.ffmpeg": "\/usr\/bin\/ffmpeg",
        "memories.vod.ffprobe": "\/usr\/bin\/ffprobe",
        "memories.video_default_quality": "-1",
        "preview_max_filesize_image": 10240,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "app_install_overwrite": [
            "video_converter",
            "files_rightclick"
        ],
        "maintenance_window_start": 23,
        "memories.db.triggers.fcu": true,
        "preview_max_x": 4096,
        "preview_max_y": 4096
    }
}

Browser

Browser name: Brave

Browser version: 1.78.102

Operating system: Ubuntu 24.04.2

Additionally, information about files that worked/ didn't work with Preview Generator

File that worked:

General
Format :	MPEG-4
Format profile :	Base Media / Version 2
Codec ID :	mp42 (isom/mp42)
File size :	18.0 MiB
Duration :	7 s 280 ms
Overall bit rate :	20.7 Mb/s
Frame rate :	30.051 FPS
Encoded date :	2025-06-09 21:22:56 UTC
Tagged date :	2025-06-09 21:22:56 UTC
Writing operating system :	Google Android 15
Writing hardware :	motorola edge 50 ultra
Video
ID :	1
Format :	AVC
Format/Info :	Advanced Video Codec
Format profile :	High@L4.1
Format settings :	CABAC / 1 Ref Frames
Format settings, CABAC :	Yes
Format settings, Reference frames :	1 frame
Format settings, GOP :	M=1, N=30
Codec ID :	avc1
Codec ID/Info :	Advanced Video Coding
Duration :	7 s 188 ms
Bit rate :	20.3 Mb/s
Width :	1 920 pixels
Height :	1 080 pixels
Display aspect ratio :	16:9
Frame rate mode :	Variable
Frame rate :	30.051 FPS
Minimum frame rate :	27.916 FPS
Maximum frame rate :	32.491 FPS
Standard :	PAL
Color space :	YUV
Chroma subsampling :	4:2:0
Bit depth :	8 bits
Scan type :	Progressive
Bits/(Pixel*Frame) :	0.325
Stream size :	17.4 MiB (97%)
Title :	VideoHandle
Language :	English
Encoded date :	2025-06-09 21:22:56 UTC
Tagged date :	2025-06-09 21:22:56 UTC
Color range :	Full
colour_range_Original :	Limited
Color primaries :	BT.601 PAL
colour_primaries_Original :	BT.709
Transfer characteristics :	BT.709
Matrix coefficients :	BT.601
matrix_coefficients_Original :	BT.709
mdhd_Duration :	7188
Codec configuration box :	avcC
Audio
ID :	2
Format :	AAC LC
Format/Info :	Advanced Audio Codec Low Complexity
Codec ID :	mp4a-40-2
Duration :	7 s 280 ms
Source duration :	7 s 211 ms
Bit rate mode :	Constant
Nominal bit rate :	256 kb/s
Channel(s) :	2 channels
Channel layout :	L R
Sampling rate :	48.0 kHz
Frame rate :	46.875 FPS (1024 SPF)
Compression mode :	Lossy
Source stream size :	225 KiB (1%)
Title :	SoundHandle
Language :	English
Encoded date :	2025-06-09 21:22:56 UTC
Tagged date :	2025-06-09 21:22:56 UTC
mdhd_Duration :	7280

General
Format :	MPEG-4
Format profile :	Base Media / Version 2
Codec ID :	mp42 (isom/mp42)
File size :	71.7 MiB
Duration :	34 s 802 ms
Overall bit rate mode :	Variable
Overall bit rate :	17.3 Mb/s
Frame rate :	30.000 FPS
Encoded date :	2018-04-22 10:47:09 UTC
Tagged date :	2018-04-22 10:47:09 UTC
Writing operating system :	Google Android 7.0
Video
ID :	1
Format :	AVC
Format/Info :	Advanced Video Codec
Format profile :	Constrained Baseline@L4
Format settings :	1 Ref Frames
Format settings, CABAC :	No
Format settings, Reference frames :	1 frame
Format settings, GOP :	M=1, N=31
Format settings, Slice count :	2 slices per frame
Codec ID :	avc1
Codec ID/Info :	Advanced Video Coding
Duration :	34 s 802 ms
Source duration :	34 s 817 ms
Bit rate mode :	Variable
Bit rate :	17.0 Mb/s
Width :	1 920 pixels
Height :	1 080 pixels
Display aspect ratio :	16:9
Frame rate mode :	Variable
Frame rate :	30.000 FPS
Minimum frame rate :	21.062 FPS
Maximum frame rate :	39.982 FPS
Color space :	YUV
Chroma subsampling :	4:2:0
Bit depth :	8 bits
Scan type :	Progressive
Bits/(Pixel*Frame) :	0.273
Stream size :	70.6 MiB (98%)
Source stream size :	70.6 MiB (98%)
Title :	VideoHandle
Language :	English
Encoded date :	2018-04-22 10:47:09 UTC
Tagged date :	2018-04-22 10:47:09 UTC
Color range :	Limited
Color primaries :	BT.709
Transfer characteristics :	BT.709
Matrix coefficients :	BT.709
mdhd_Duration :	34802
Codec configuration box :	avcC
Audio
ID :	2
Format :	AAC LC
Format/Info :	Advanced Audio Codec Low Complexity
Codec ID :	mp4a-40-2
Duration :	34 s 731 ms
Bit rate mode :	Constant
Bit rate :	192 kb/s
Channel(s) :	2 channels
Channel layout :	L R
Sampling rate :	48.0 kHz
Frame rate :	46.875 FPS (1024 SPF)
Compression mode :	Lossy
Stream size :	814 KiB (1%)
Title :	SoundHandle
Language :	English
Encoded date :	2018-04-22 10:47:09 UTC
Tagged date :	2018-04-22 10:47:09 UTC
mdhd_Duration :	34731

Files that didn't work:

General
Format :	MPEG-4
Format profile :	Base Media / Version 2
Codec ID :	mp42 (isom/mp42)
File size :	88.8 MiB
Duration :	1 min 0 s
Overall bit rate :	12.2 Mb/s
Frame rate :	29.891 FPS
Encoded date :	2025-06-07 18:16:24 UTC
Tagged date :	2025-06-07 18:16:24 UTC
Recorded location :	
Writing operating system :	Google Android 15
Writing hardware :	Samsung Galaxy S25 (SM-S931B)
com.android.video.temporal_layers_count :	Unknown kind of value!
com.samsung.android.utc_offset :	+0200
Video
ID :	1
Format :	HEVC
Format/Info :	High Efficiency Video Coding
Format profile :	Main 10@L4@Main
Codec ID :	hvc1
Codec ID/Info :	High Efficiency Video Coding
Duration :	1 min 0 s
Source duration :	1 min 0 s
Bit rate :	12.0 Mb/s
Width :	1 920 pixels
Height :	1 080 pixels
Display aspect ratio :	16:9
Rotation :	180°
Frame rate mode :	Variable
Frame rate :	29.891 FPS
Minimum frame rate :	15.005 FPS
Maximum frame rate :	33.645 FPS
Real frame rate :	30.000 FPS
Color space :	YUV
Chroma subsampling :	4:2:0
Bit depth :	10 bits
Bits/(Pixel*Frame) :	0.193
Stream size :	86.9 MiB (98%)
Source stream size :	86.9 MiB (98%)
Title :	VideoHandle
Language :	English
Encoded date :	2025-06-07 18:16:24 UTC
Tagged date :	2025-06-07 18:16:24 UTC
Color range :	Limited
Color primaries :	BT.2020
Transfer characteristics :	HLG
Matrix coefficients :	BT.2020 non-constant
mdhd_Duration :	60989
Codec configuration box :	hvcC
Audio
ID :	2
Format :	AAC LC
Format/Info :	Advanced Audio Codec Low Complexity
Codec ID :	mp4a-40-2
Duration :	1 min 0 s
Bit rate mode :	Constant
Bit rate :	256 kb/s
Channel(s) :	2 channels
Channel layout :	L R
Sampling rate :	48.0 kHz
Frame rate :	46.875 FPS (1024 SPF)
Compression mode :	Lossy
Stream size :	1.86 MiB (2%)
Title :	SoundHandle
Language :	English
Encoded date :	2025-06-07 18:16:24 UTC
Tagged date :	2025-06-07 18:16:24 UTC

General
Format :	MPEG-4
Format profile :	Base Media / Version 2
Codec ID :	mp42 (isom/mp42)
File size :	29.4 MiB
Duration :	20 s 45 ms
Overall bit rate :	12.3 Mb/s
Frame rate :	29.970 FPS
Encoded date :	2025-06-09 20:48:58 UTC
Tagged date :	2025-06-09 20:48:58 UTC
Writing operating system :	Google Android 15
Writing hardware :	Samsung Galaxy S25 (SM-S931B)
com.samsung.android.utc_offset :	+0200
Video
ID :	1
Format :	AVC
Format/Info :	Advanced Video Codec
Format profile :	High@L3.1
Format settings :	CABAC / 1 Ref Frames
Format settings, CABAC :	Yes
Format settings, Reference frames :	1 frame
Format settings, GOP :	M=1, N=30
Codec ID :	avc1
Codec ID/Info :	Advanced Video Coding
Duration :	20 s 45 ms
Bit rate :	12.0 Mb/s
Width :	1 280 pixels
Height :	720 pixels
Display aspect ratio :	16:9
Frame rate mode :	Variable
Frame rate :	29.970 (29970/1000) FPS
Minimum frame rate :	19.235 FPS
Maximum frame rate :	30.020 FPS
Real frame rate :	30.000 FPS
Standard :	PAL
Color space :	YUV
Chroma subsampling :	4:2:0
Bit depth :	8 bits
Scan type :	Progressive
Bits/(Pixel*Frame) :	0.436
Stream size :	28.8 MiB (98%)
Title :	VideoHandle
Language :	English
Encoded date :	2025-06-09 20:48:58 UTC
Tagged date :	2025-06-09 20:48:58 UTC
Color range :	Limited
Color primaries :	BT.709
Transfer characteristics :	BT.709
Matrix coefficients :	BT.709
mdhd_Duration :	20045
Codec configuration box :	avcC
Audio
ID :	2
Format :	AAC LC
Format/Info :	Advanced Audio Codec Low Complexity
Codec ID :	mp4a-40-2
Duration :	20 s 32 ms
Bit rate mode :	Constant
Bit rate :	256 kb/s
Channel(s) :	2 channels
Channel layout :	L R
Sampling rate :	48.0 kHz
Frame rate :	46.875 FPS (1024 SPF)
Compression mode :	Lossy
Stream size :	626 KiB (2%)
Title :	SoundHandle
Language :	English
Encoded date :	2025-06-09 20:48:58 UTC
Tagged date :	2025-06-09 20:48:58 UTC

General
Format :	MPEG-4
Format profile :	Base Media / Version 2
Codec ID :	mp42 (isom/mp42)
File size :	40.5 MiB
Duration :	19 s 662 ms
Overall bit rate :	17.3 Mb/s
Frame rate :	30.000 FPS
Encoded date :	2023-06-21 19:18:51 UTC
Tagged date :	2023-06-21 19:18:51 UTC
Writing operating system :	Google Android 13
Writing hardware :	Samsung SM-G990B2
Video
ID :	1
Format :	AVC
Format/Info :	Advanced Video Codec
Format profile :	High@L4
Format settings :	CABAC / 1 Ref Frames
Format settings, CABAC :	Yes
Format settings, Reference frames :	1 frame
Format settings, GOP :	M=1, N=30
Codec ID :	avc1
Codec ID/Info :	Advanced Video Coding
Duration :	19 s 662 ms
Bit rate :	17.0 Mb/s
Width :	1 920 pixels
Height :	1 080 pixels
Display aspect ratio :	16:9
Rotation :	90°
Frame rate mode :	Variable
Frame rate :	30.000 FPS
Minimum frame rate :	29.278 FPS
Maximum frame rate :	30.822 FPS
Real frame rate :	30.000 FPS
Standard :	PAL
Color space :	YUV
Chroma subsampling :	4:2:0
Bit depth :	8 bits
Scan type :	Progressive
Bits/(Pixel*Frame) :	0.273
Stream size :	39.8 MiB (98%)
Title :	VideoHandle
Language :	English
Encoded date :	2023-06-21 19:18:51 UTC
Tagged date :	2023-06-21 19:18:51 UTC
Color range :	Limited
Color primaries :	BT.709
Transfer characteristics :	BT.709
Matrix coefficients :	BT.709
Codec configuration box :	avcC
Audio
ID :	2
Format :	AAC LC
Format/Info :	Advanced Audio Codec Low Complexity
Codec ID :	mp4a-40-2
Duration :	19 s 632 ms
Source duration :	19 s 605 ms
Bit rate mode :	Constant
Bit rate :	256 kb/s
Channel(s) :	2 channels
Channel layout :	L R
Sampling rate :	48.0 kHz
Frame rate :	46.875 FPS (1024 SPF)
Compression mode :	Lossy
Stream size :	613 KiB (1%)
Source stream size :	613 KiB (1%)
Title :	SoundHandle
Language :	English
Encoded date :	2023-06-21 19:18:51 UTC
Tagged date :	2023-06-21 19:18:51 UTC
mdhd_Duration :	19632

[HristiyanBostandzhiev]

I'm experiencing the same issue. I was using Nextcloud 31.0.6 via docker-compose, and all videos had previews. After upgrading to 31.0.9, the old previews were visible, but when I deleted them to regenerate, many videos failed to generate previews.

The logs show "no provider found." I tried generating previews manually with ffmpeg on the host, but got errors related to color and rotation. I also tried converting the videos with ffmpeg on both Linux and Windows, but the same errors occurred.

[yoGhurrt1]

I'm experiencing the same issue. I was using Nextcloud 31.0.6 via docker-compose, and all videos had previews. After upgrading to 31.0.9, the old previews were visible, but when I deleted them to regenerate, many videos failed to generate previews.

The logs show "no provider found." I tried generating previews manually with ffmpeg on the host, but got errors related to color and rotation. I also tried converting the videos with ffmpeg on both Linux and Windows, but the same errors occurred.

Can you share what parameters you used for manual generation with ffmpeg? I would try it myself to check if I have same situation. That would also suggest maybe it's problem somewhere in ffmpeg instead/additionally to this plugin.

[invario]

Are these locally stored videos, or some form of external storage mounted in NC?

Also, I currently have a Samsung GS25+ and previews function fine. I also have tons (thousands) of videos recorded from Samsung phones throughout the years. I purged all my previews yesterday for something unrelated and used Preview Generator to regenerate what ended up being 24GB of thumbnails and it went off without a hitch. (Samsung Galaxy S 4G, GS3, GS4, GS5, GS6, GS8, GS10, GS21+, GS23+,GS25+, A54, and several Samsung Tablets.)

So I'm very curious what the outcome of this might be.

[yoGhurrt1]

Are these locally stored videos, or some form of external storage mounted in NC?

Also, I currently have a Samsung GS25+ and previews function fine. I also have tons (thousands) of videos recorded from Samsung phones throughout the years. I purged all my previews yesterday for something unrelated and used Preview Generator to regenerate what ended up being 24GB of thumbnails and it went off without a hitch. (Samsung Galaxy S 4G, GS3, GS4, GS5, GS6, GS8, GS10, GS21+, GS23+,GS25+, A54, and several Samsung Tablets.)

So I'm very curious what the outcome of this might be.

They're on external smb share connected to Nextcloud. Not sure if I tried it locally, I'll test it and confirm.

[invario]

Okay, so one of the NC 31 updates disabled preview generation for videos for all external mounts because on certain video files (such as the ones generated by Samsung phones like ours) there is a header at the end of the file instead of the beginning.

NC 31 and 32 will not generate new previews for any videos on external storage because it would require downloading the entire video file to get that header and on external storage that is actually remote over a slower connection that could be really really slow and also cost people money that are paying by bandwidth usage (e.g. S3)

NC 33 (just released) has code I worked on integrated that fixes this problem and previews for videos will generate properly.

So this isn't a problem with Preview Generator, and it should be fixed by updating to NC 33.

[yoGhurrt1]

I have this problem as far as I remember and this NC instance exists for over 2 years, which means I've started with v26. I didn't have chance yet to chceck this problem with local drive, so I'll confirm that.

[st3iny]

Hi, thanks for the report. I'd love to help out here but I think this is probably not a bug in Nextcloud or the Previewgenerator app.

AFAIK, the movie preview generator class runs Ffmpeg behind the scenes to generate thumbnails. It is implemented in a way to handle errors gracefully. So, when Ffmpeg fails to generate a preview for some reason, the provider will just report that it can't handle the file. And you can easily confirm this by running Ffmpeg manually by hand. If it fails to read the movie file (and generate a thumbnail) this is most likely the reason: Your installed version of Ffmpeg is not able to handle/decode the video file.

It could also be a problem with the storage. If the file exists on an external storage, a failing connection might also be a reason for the preview generation to fail.

[st3iny]

PS: If anyone is able to share a video file that is consistently failing, I might be able to debug further.

[invario]

@yoGhurrt1 What is the output of just running ffmpeg?

Also, the command line used for preview generation ffmpeg -y -ss 1 -i INPUT.mp4 -f mjpeg -vframes 1 OUTPUT.jpg if you want to test that for yourself.

[yoGhurrt1]

Sorry, I just couldn't find time to test this earlier.
Looks like you're onto something - tested with a few files and compared result. I copied same file through Nextcloud interface to directory on Nextcloud server and also on network share that's connected to NC. Each time thumbnail for "local" file showed right away. Files were also from two different Samsung phones, so it isn't just a luck of some update on current phone.
However - if this is a problem related to network share - that means this problem should be related to any video on network share, whereas, I have problem only with files from Samsung phones.
Maybe this is truly related to what you mentioned, so it should be fixed in NC 33, but I have some doubts about it. Either way, that's something to also test and (or not) confirm.

Regarding ffmpeg:

  built with gcc 13 (Ubuntu 13.3.0-6ubuntu2~24.04)
  configuration: --disable-decoder=amrnb --disable-gnutls --disable-liblensfun --disable-libopencv --disable-podpages --disable-sndio --disable-stripping --enable-avfilter --enable-chromaprint --enable-frei0r --enable-gcrypt --enable-gpl --enable-ladspa --enable-libaom --enable-libaribb24 --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libdc1394 --enable-libdrm --enable-libdvdnav --enable-libdvdread --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libharfbuzz --enable-libiec61883 --enable-libjack --enable-libjxl --enable-libmp3lame --enable-libmysofa --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libplacebo --enable-libpulse --enable-librabbitmq --enable-librist --enable-librsvg --enable-librubberband --enable-libshine --enable-libsmbclient --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libsvtav1 --enable-libtesseract --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-nonfree --enable-openal --enable-opencl --enable-opengl --enable-openssl --enable-postproc --enable-pthreads --enable-shared --enable-version3 --incdir=/usr/include/x86_64-linux-gnu --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --toolchain=hardened --enable-vaapi --enable-libvpl --enable-libxavs2 --enable-libdavs2 --enable-libvmaf --enable-librav1e --enable-libvvenc --enable-libilbc --enable-libklvanc --enable-libfdk-aac --enable-libkvazaar --enable-omx --cc=x86_64-linux-gnu-gcc --cxx=x86_64-linux-gnu-g++ --disable-altivec --shlibdir=/usr/lib/x86_64-linux-gnu
  libavutil      59. 39.100 / 59. 39.100
  libavcodec     61. 19.101 / 61. 19.101
  libavformat    61.  7.100 / 61.  7.100
  libavdevice    61.  3.100 / 61.  3.100
  libavfilter    10.  4.100 / 10.  4.100
  libswscale      8.  3.100 /  8.  3.100
  libswresample   5.  3.100 /  5.  3.100
  libpostproc    58.  3.100 / 58.  3.100
Universal media converter
usage: ffmpeg [options] [[infile options] -i infile]... {[outfile options] outfile}...

Because it was some time ago, I think I manually updated ffmpeg on server just to be sure this program isn't a factor in this scenario.

[invario]

It is recording device specific. Samsung phones just happen to be a line of devices that places the MOOV atom at the end of its MP4 files.

For an in depth discussion and technical explanation, see the follow issue and fix (which went into NC 33)
nextcloud/server#53469
nextcloud/server#53952

Also, I misspoke earlier. The update that caused this on NC31/32 will still attempt to generate previews for videos for external storage, but only by retrieving the first 5MB of the file. Then it gives up if it fails. So as you can see, the location of the MOOV atom is crucial.