Why doesn't multimedia/HTML5 redirection work?

We deliberately disabled client-side multimedia and HTML5 rendering in TLXOS for HDX and Horizon modes because it just wasn't worth the hassle.  The Linux ports of Citrix Workspace App and VMware Horizon Client use GStreamer for multimedia and HTML5 redirection, and this is problematic for several reasons:

• In both cases (HDX and Horizon), the default GStreamer pipeline uses software-only rendering (no hardware accleration).  Someone with expert GStreamer skills would have to heavily customise the client's GStreamer pipeline in order to make use of hardware acceleration, and even then this would be fragile and very client-hardware-specific.
• GStreamer support for OpenMAX IL (Raspberry Pi hardware accleration scheme) is wildly experimental at best.  We tried it, and it isn't sufficiently reliable or robust.
• In both cases, hardware H.264 decoding of the entire screen does a pretty good job of rendering video windows anyway, so multimedia redirection would add very little even if it were hardware-accelerated.
• In order to even get the software rendering GStreamer pieplines to work, a full GStreamer install is required, which has a very large disk footprint.
• Horizon Client still uses GStreamer 0.10, which is obsolete (not available in Debian Stretch and later).  Workspace App, thankfully, has at least upgraded to GStreamer 1.0.  We didn't want to install both GStreamer 1.0 and 0.10, so our repackaged Horizon Client doesn't even include the MMR extension.
• Multimedia acceleration only works for specific server-side applications (ones using the Windows Media Foundation framework, such as Windows Media Player and Chrome).  Common multimedia applications such as VLC media player would not use MMR in any case.

The RDP client (FreeRDP 2.0) automatically renders video portions of the display to the best of its ability using FFMPEG.  In recent TLXOS RPi releases, for better use of Pi hardware acceleration we have provided FreeRDP with its own private FFMPEG libraries with added MMAL support.

We removed the "Redirect Video" option from our GUIs in TLXOS 4.8.0 and TMS 8.2.0.