Automating Video Workflows With PowerShell

Linking today to some great content from another Ian (ProTip: get to know an Ian, we’re full of useful knowledge). Ian Morrish posts about automating a variety of methods of automating A/V equipment using PowerShell. Lots of useful stuff in here.

No Windows? No worries, you can install PowerShell on MacOS and Linux too.

I’ve put some feelers out to some of my streaming equipment vendors to find out what kind of automation hooks and APIs they support.

Meanwhile, Wowza has a REST API for both its Streaming Engine and Cloud products. Integrating this into PowerShell should be relatively straightforward. Any PowerShell wizards wanna take a stab at it?

Stay tuned.


Instant Replays on Wowza

One of the useful features of Wowza is its ability to record a stream to disk and then be able to use that recording for a replay. In version 3.5, it would simply take the stream name, slap an MP4 extension on the end, and version any previous ones with _0, _1, etc. In 3.6, the default naming scheme for these recordings was a timestamp, with a configuration option to use the legacy naming convention. In Version 4, it appears this legacy naming convention option has disappeared altogether, meaning you can’t set up a player to just play back “streamname.mp4” and it would always grab the most recent one. EDIT: It appears that this loss of functionality was unintentional and has been classified as a bug, which should be fixed very soon.

This became a problem for one of my clients after their Wowza server got updated to V4. It wasn’t practical to re-code the player every week, or to go into the server and manually rename the file. Since it’s on a Windows server, PowerShell to the rescue:

$basepath= "C:\Program Files (x86)\Wowza Media Systems\Wowza Streaming Engine 4.0.3\content\"
$replayfile =  gci $basepath\streamname*.mp4 | sort LastWriteTime | select -last 1
$link = $replayfile.Name

cmd /c del $basepath\replay.mp4
cmd /c mklink $basepath\replay.mp4 $basepath\$link

I then put this into a scheduled task, with time-based triggers. Powershell is a little tricky to get into a scheduled task, but I finally got the syntax right:

Action: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe
Arguments: -nologo -file “C:\Program Files (x86)\Wowza Media Systems\Wowza Streaming Engine 4.0.3\content\replay.ps1”

If you’re on Linux or OSX, you can do this in bash instead:


unset -v replayfile
for file in "$basepath"/streamname*.mp4
  [[ -z $replayfile || $file -nt $replayfile ]] && replayfile=$file
rm -f $basepath/replay.mp4
ln -s $replayfile $basepath/replay.mp4

and put it in your crontab (this example is every sunday at 11:30am)

30 11 * * 0 /bin/bash /usr/local/WowzaMediaServer/content/