Latency using HQPlayer Embedded (hqplayerd)

[simoncn]

In my test environment (RPi3 for server and RPi4 for renderer, 16/44 FLAC files, no transcoding), the great majority of the delay between tracks that causes these gaps is within HQPlayer (specifically, within the Rygel UPnP stack that HQPlayer uses to enable it to act as a UPnP renderer). Because HQPlayer doesn't use the UPnP gapless protocol, any significant delay during track changing breaks gapless playback.

If HQPlayer is running on a faster machine, renderer track-changing delay will be reduced and any server delay will come into play. Increased resolution and/or server-side transcoding will increase server delay.

The only way to make this work correctly in all cases is for HQPlayer to implement the UPnP gapless protocol. This enables the renderer to start streaming the next track before the current track has finished playing.