My video (.mkv) thumbnails are green (or monochromatic)?
This answer is based on Another answer posted by Elder Geek, this just makes it easy for new users to execute
Original Work
For 17.04
Enable Multiverse and Universe repositories
Open the software and updates app and select multiverse and universe repositories
and run the following command after enabling them
sudo apt-get update
Install ubuntu-restricted-extras
sudo apt-get install ubuntu-restricted-extras
This command should do it, You'll need to use the Tab key to highlight the OK button for the mscore fonts package and hit enter to accept the agreement, How do I install the ubuntu-restricted extras package? (for more details)
You don't need to install ubuntu-restricted-extras if you've already installed media drivers while installing ubuntu
Install ffmpeg
sudo apt-get install ffmpeg ffmpegthumbnailer
These commands will install ffmpeg, after that delete all the existing thumbnails. by doing
rm -r ~/.cache/thumbnails
Change the job of creating thumbnails from Totem to ffmpeg
sudo nano /usr/share/thumbnailers/totem.thumbnailer
a text file will open up, replace all the text inside it with the following
[Thumbnailer Entry]
TryExec=ffmpegthumbnailer
Exec=ffmpegthumbnailer -s %s -i %i -o %o -c png -f -t 10
MimeType=application/mxf;application/ogg;application/ram;application/sdp;application/vnd.ms-wpl;application/vnd.rn-realmedia;application/x-extension-m4a;application/x-extension-mp4;application/x-flash-video;application/x-matroska;application/x-netshow-channel;application/x-ogg;application/x-quicktimeplayer;application/x-shorten;image/vnd.rn-realpix;image/x-pict;misc/ultravox;text/x-google-video-pointer;video/3gpp;video/dv;video/fli;video/flv;video/mp2t;video/mp4;video/mp4v-es;video/mpeg;video/msvideo;video/ogg;video/quicktime;video/vivo;video/vnd.divx;video/vnd.rn-realvideo;video/vnd.vivo;video/webm;video/x-anim;video/x-avi;video/x-flc;video/x-fli;video/x-flic;video/x-flv;video/x-m4v;video/x-matroska;video/x-mpeg;video/x-ms-asf;video/x-ms-asx;video/x-msvideo;video/x-ms-wm;video/x-ms-wmv;video/x-ms-wmx;video/x-ms-wvx;video/x-nsv;video/x-ogm+ogg;video/x-theora+ogg;video/x-totem-stream;audio/x-pn-realaudio;audio/3gpp;audio/ac3;audio/AMR;audio/AMR-WB;audio/basic;audio/midi;audio/mp2;audio/mp4;audio/mpeg;audio/ogg;audio/prs.sid;audio/vnd.rn-realaudio;audio/x-aiff;audio/x-ape;audio/x-flac;audio/x-gsm;audio/x-it;audio/x-m4a;audio/x-matroska;audio/x-mod;audio/x-mp3;audio/x-mpeg;audio/x-ms-asf;audio/x-ms-asx;audio/x-ms-wax;audio/x-ms-wma;audio/x-musepack;audio/x-pn-aiff;audio/x-pn-au;audio/x-pn-wav;audio/x-pn-windows-acm;audio/x-realaudio;audio/x-real-audio;audio/x-sbc;audio/x-speex;audio/x-tta;audio/x-wav;audio/x-wavpack;audio/x-vorbis;audio/x-vorbis+ogg;audio/x-xm;application/x-flac;
To save updated file in Nano press Ctrl + X and then type y and enter. How to edit files in a terminal with nano?
You can use other text editing apps to edit /usr/share/thumbnailers/totem.thumbnailer file if you're not comfortable using nano
and the restart nautilus
nautilus -q
Clear all the thumbnails again and check if you're problem is solved
rm -r ~/.cache/thumbnails
The command above will clear all the thumbnails again, go check them, they will not be monochromatic now'
If you're losing Mp3/flac thumbnails after doing this, then try this approach instead
Based on the results of our testing, I believe that the issue is totem generation of thumbnails for nautilus when utilizing the HEVC codec. As I recall, totem utilizes gstreamer plugins for this task. While I would normally expect the installation of the ubuntu-restricted-extras package to resolve most codec issues, in this case it appears that's not true. It seems that the the x265 HEVC support isn't included. There are a couple of options, I can suggest.
Edit: After testing on 17.04 live media created from ubuntu-17.04-desktop-amd64.iso today (after confirming that the downloaded iso was uncorrupted by checking the hash)I can confirm that the following approach produces the desired results of appropriately colored thumbnails.
Enable both the multiverse and universe repositories via Software & Updates on the Ubuntu Software Tab by checking the aforementioned boxes. Install ubuntu-restricted-extras via either the software center or CLI with sudo apt update && sudo apt install ubuntu-restricted-extras You'll need to use the Tab key to highlight the OK button for the mscore fonts package and hit enter to accept the agreement. Then all the requisite packages will be downlowded and installed. Close Nautilus if it's open and then refresh your thumbnails with rm -r ~/.cache/thumbnails
The options below may have some value in certain situations so I'll leave them as is.
A) Install the libavcodec-extra57 package and all it's dependencies. This package contains the ffmpeg library with additional de/encoders for audio/video codecs. I believe the critical dependency here is the libx265-110 library that the aforementioned libavcodec-extra57 package relies on for HEVC encoding/decoding.
You can install the libavcodec-extra57 package after first completing the instrucions at How do I enable the "Universe" repository? and then installing the package either through the software center or via the command line with sudo apt-get update && sudo apt-get install libavcodec-extra57
If this by itself doesn't resolve the issue, you can add the step of changing to a different thumb nailer using one of the options described in Way to make video-thumbnails generate from VLC instead of Totem?
B) If that doesn't do the trick, utilize the libde265 package also in the Universe repository. I had good results with this package on 14.04 (I had to install it via PPA back then) It looks like I'm still using it successfully under 16.04 (likely an upgrade rather than a clean install.
dpkg -l libde265
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-===========================-==================-==================-===========================================================
ii libde265:amd64 1.0.2-1ppa1~trusty amd64 Open H.265 video codec implementation
Regardless of the approach you'll have to regenerate your thumbnails again.
Note: I always recommend backups to make it easy to revert back if changes don't have the appropriate result. It's become clear to me that many don't bother to do this any where near as often as they should.