On Tue, Jun 25, 2019 at 2:45 PM Antony Awaida <[email protected]> wrote:
> Hi Guac team: > > One of our users is using a music sequencer (Ableton LIve) and he > experiences a small lag between the sound and video. ... > How much lag does the user experience specifically? What would cause such a delay.? I have read somewhere that the guac > protocol tries to make sure the sound and video are in sync on a frame. > Guacamole does, yes. It's not an aspect of the protocol as much as it's an aspect of the client. The Guacamole server will stream both graphical and audio data as quickly as it can, essentially as soon as it's received. Along with this data is the "sync" timestamp that denotes the end of Guacamole's concept of a frame. The audio player within the client tracks the timestamp of the display (the timestamp of the graphics that most recently finished rendering) relative to the timestamp of the audio stream (the timestamp of the audio most recently played) and alters the scheduling of future audio playback to compensate for any time difference. In practice, whether the user will notice lag will also depend on the protocol used by the remote desktop server. If I remember correctly, RDP always sends audio packets that are roughly 300ms in size. Since that amount of audio will have to have accumulated remotely before the RDP server can send it, that guarantees at least that much lag before Guacamole even receives the packet. - Mike
