<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - Sound output using DisplayPort is NOT played during the first 3-5 seconds (on several audio hardware)" href="https://bugs.freedesktop.org/show_bug.cgi?id=92889#c23">Comment # 23</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - Sound output using DisplayPort is NOT played during the first 3-5 seconds (on several audio hardware)" href="https://bugs.freedesktop.org/show_bug.cgi?id=92889">bug 92889</a> from <a class="email" href="mailto:Paul.Hancock.17041993@live.com" title="Paul <Paul.Hancock.17041993@live.com>"> Paul</a> <pre>(In reply to Alex Deucher from <a href="show_bug.cgi?id=92889#c22">comment #22</a>) > FWIW, the same thing happens with some receivers and various media devices > (Roku, DVD player, etc.). I think it takes some receivers and displays a > few seconds to detect and enable the audio stream. It might be dependent on > the display or receiver. It _is_ in fact normal for there to be a significant delay in initialising HDMI and DP audio, it's because of the multiple handshakes that have to occur between the devices. For standard internal and USB devices, the only long part of the init is creating the buffers, but for HDMI and DP it's more like this; - check controller capability and init controller (mostly in-memory from POST) - check link status, collect audio endpoint data (slow-ish) - ensure controller and endpoint can use desired format - initialise audio endpoint (again, slow-ish, requires re-configuring the cable bitstream) - create buffers - wait for endpoint to be ready, then init buffer stream Usually this is all done within 250-500ms, but indeed for some endpoint devices it may take a lot longer and especially if they need to relay info between other connected devices (ie; a receiver or a de-embed switch), content protection protocols also increase the complexity. We'd need a _lot_ more info to know whether it's just the endpoint or if the driver could be optimised more, for example a basic test with basic formats between windows/OSX/both and the xorg drivers, ideally with multiple HDMI/DP controllers and endpoints. I will note as well; the HDMI DAC takes about 5 seconds for a full init to finish, however this includes the video init as well as audio, windows seems to collect all the info it needs from the get-go instead of requesting later.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the assignee for the bug.</li> </ul> </body> </html>