<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_NEW " title="NEW - bluetooth audio out of sync when connection temporarily drops" href="https://bugs.freedesktop.org/show_bug.cgi?id=58746#c14">Comment # 14</a> on <a class="bz_bug_link bz_status_NEW " title="NEW - bluetooth audio out of sync when connection temporarily drops" href="https://bugs.freedesktop.org/show_bug.cgi?id=58746">bug 58746</a> from <a class="email" href="mailto:paco3346@gmail.com" title="paco3346@gmail.com">paco3346@gmail.com</a> <pre>(In reply to Dmitry Kalyanov from <a href="show_bug.cgi?id=58746#c8">comment #8</a>) > Created <a href="attachment.cgi?id=125291" name="attach_125291" title="Proof-of-concept patch">attachment 125291</a> <a href="attachment.cgi?id=125291&action=edit" title="Proof-of-concept patch">[details]</a> <a href='page.cgi?id=splinter.html&bug=58746&attachment=125291'>[review]</a> [review] > Proof-of-concept patch > > I've solved this issue for myself - I've been using pulseaudio with my > changes for several months now with no major problems. > > I've noticed that every time signal degrades audio gets more out of sync - > up to about 10-15 seconds (if I remember correctly). > > I've debugged bluez5 pulseaudio module and suspect that the problem lies in > buffering for bluetooth socket. Here's my analysis: > > 1) Pulseaudio detects BT signal drop when write() on bluetooth socket > returns EAGAIN (i.e., when the buffer is full). > 2) Bluetooth socket buffer is quite big (by default) > 3) When pulseaudio stops sending audio packets to BT socket the buffer still > contains a lot of packets > 4) pulseaudio considers those packets as successfully sent - but they aren't > 5) BT connection seems to never be able to "catch up" with the amount of > buffered packets and audio becomes out-of-sync. > > So here's my patch. The main change is to decrease the buffer size as much > as possible. I've experimented and found out that settings buffer size to > 2x-5x of packet size works best for me. This ensures that audio lag won't > accumulate after BT signal degradation while preventing audio skipping due > to buffer underruns. Audio still may skip (sometimes several times in a row) > - but without the lag after BT signal restores. > > Unfortunately with this patch bluetooth microphone (headset profile) won't > work - since I don't use one and couldn't test it. I hope that someone would > be able to pick it up and make into a form that would be possible to merge > in master branch. > > The changes are contained in attached path on github: > <a href="https://github.com/dmitryvk/pulseaudio/commit/">https://github.com/dmitryvk/pulseaudio/commit/</a> > 12b13c75d3a9b377e0f7de7c86116e3af41ce5ee. Patch was developed against > Pulseaudio-8.0 but it works with Pulseaudio-9.0. Genius! I understand the problems with this patch but for now it's music to my ears (pun intended). Using on Arch with Pulseaudio 9.</pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> <li>You are the assignee for the bug.</li> </ul> </body> </html>