HDMI output
What it is for
Section titled “What it is for”A lobby display, a day-room television, a waiting-room screen. Somewhere a single fixed channel needs to be on all day, the display is close enough to the appliance to be reached with a cable, and installing a set-top box or a small-form-factor PC to do it would be disproportionate.
It is not a monitoring feature. If you want to check that a channel is working, use the browser preview or the UDP bitrate figure — see Monitoring and metrics.
Configuration
Section titled “Configuration”The HDMI page has a channel picker, three output selections and a switch.
Name
A label for the output, used in the status display and the log view. It is not written into any transport stream, because nothing here produces one.
Channel (UDP)
Which of your channels to show. The player joins that channel’s multicast group like any receiver on the network, so what appears on the screen is exactly what the set-top boxes are getting. It plays channels only: there is no free-form URL, and a source Castmux is not already carrying needs to be added as a channel first. If the selected channel is deleted, the output stops and its log says why.
Video driver, Output device (GPU), Audio device
Where the picture and sound go. Each list is filled from what this appliance reports it can drive, so every option is something the player can actually open. Leave all three at their defaults (mpv default, auto) unless the screen stays black or silent. Set the output device on hardware with more than one display controller, where the default can be the wrong connector. Choose none as the audio device for a silent picture.
Active
Starts and stops playback. Turning it off stops the player; turning it on starts it and keeps it running.
The same settings live under hdmi_stream in the configuration file — see HDMI output settings.
Status and logs
Section titled “Status and logs”The output reports whether it is currently playing and how long it has been doing so. Uptime is the more useful of the two: a status that reads as playing but an uptime that keeps resetting to a few seconds means the player is crashing and being restarted, which is a different fault from one that will not start at all.
A log view shows the player’s own output. This is where to look when a URL plays in VLC on a laptop but not here — usually a codec the appliance’s display pipeline cannot handle, or a source the appliance cannot reach.
Automatic restart
Section titled “Automatic restart”If the player exits — a crash, a source that disappears, a stream that ends — it is restarted automatically. A screen in a public area that has been showing a blank display since some point on Tuesday is a fault nobody reports and everybody sees, so recovering without intervention is the sensible default. The uptime figure is what tells you it has been happening.
Independence from UDP channels
Section titled “Independence from UDP channels”The HDMI output is a separate process from the channels. It does not occupy a multicast group, it does not appear in a DVB-C multiplex, and it has no destination address.
One consequence is worth knowing: because the HDMI output joins the selected channel’s multicast group like any other receiver, it counts as a viewer for on-demand streaming. An on-demand channel shown on the HDMI output will never stop, which is correct behaviour and occasionally surprising.
Output device
Section titled “Output device”By default, video goes to the appliance’s display and audio is carried over HDMI with it. The Output device and Audio device selections above change that when the default is wrong for the hardware.
Audio device names differ from one board to the next. A setting copied from a different model of appliance is the usual reason the player will not start. The log view shows the player’s own error. Setting the lists back to their defaults, or picking again from what this appliance offers, is the fix.