Some tech documentation and snippets, finally organized.
Posts tagged as multimedia

Stop Chromium from listening on UDP Port 5353

Setting chrome://flags/#device-discovery-notifications to "disabled" as well as the configuration line export CHROMIUM_FLAGS="$CHROMIUM_FLAGS --media-router=0" in a file under /etc/chromium.d/ do not prevent the Chromium browser from listening on UDP port 5353 any longer. Instead, a policy has to be defined under /etc/chromium/policies/managed/:

$ mkdir -p /etc/chromium/policies/managed
$ echo '{ "EnableMediaRouter": false }' > /etc/chromium/policies/managed/disable_mediarouter.json

For Google Chrome, this policy has to reside under /etc/opt/chrome/policies/managed/.

Mount an USB connected Android based smartphone into Linux

​User-mountable and world-readable, using fuse and jmtpfs:

Install required software:

$ apt-get install fuse jmtpfs usbutils

Connect the smartphone with an USB data cable and read out required information:

$ lsusb

The command returns a list of all connected USB devices; the line for my Moto G4 play looks like this:

Bus 001 Device 003: ID 22b8:2e82 Motorola PCS

Now use the printed Vendor and Product ID (before resp. after the colon) to create the according udev rule:

$ echo 'SUBSYSTEM=="usb", ATTR{idVendor}=="22b8", ATTR{idProduct}=="2e82", SYMLINK+="libmtp-%k", MODE="660", GROUP="audio", ENV{ID_MTP_DEVICE}="1", ENV{ID_MEDIA_PLAYER}="1"' >> /etc/udev/rules.d/55-android.rules

Create mountpoint, make sure that you are in the audio group and test setup:

$ mkdir /media/motomobil
$ chmod a+rwx /media/motomobil/
$ jmtpfs -o allow_other /media/motomobil/
$ fusermount -u /media/motomobil/

jmtpfs will grab the first available device. Allternatively, the device can be specified with the -device=<busLocation>,<devNum> switch, to dump the parameters, run jmtpfs --listDevices.

Add fstab entry:

$ echo "jmtpfs       /media/motomobil       fuse       noauto,nodev,allow_others,rw,user,noatime       0       0" >> /etc/fstab

Burning a mixed-mode CD-R

It is possible to "enhance" an audio CD with arbitrary files as a bonus track. The following post shows how to create such a mixed-mode CD or enhanced CD on the command line.

Create suitable wav files with libav-tools

$ for i in $(ls); do avconv -i $i /path/to/outdir/$i.wav; done

Note: ffmpeg will work as well, with the same syntax and options: just /avconv/ffmpeg/.

Burn the audio-tracks

$ cd $WAVDIR
$ wodim -v dev=/dev/sr0 speed=4 -multi -audio *.wav

The -multi switch (for multi session) is necessary to prevent wodim from closing the disk after burning. Additionally, I use the slow speed=4 option to burn sharper delimited dots and thus enhance the disk's readability in older (or dusty) audio players.

Analyze the audio-session and prepare the "bonus track"

$ TRACKINFO=`cdrecord -msinfo dev=1,0,0`

In this case, the first session started at sector 0 and the following will start at sector 105248. This information can now be passed to mkisofs or the newer xorrisofs:

$ xorrisofs -J -r -C $TRACKINFO -V $16_CHAR_DISKLABEL -o /path/to/data.iso /path/to/data

Append the iso to the disk

$ wodim -v dev=/dev/sr0 -data /path/to/data.iso

The resulting CD will serve the first session to all common audio CD players, while the second (data) session can be accessed with a CD-ROM drive.

Note: Not all CD-ROM drives support mixed-mode media - some may fail to access the audio tracks from the first session.