如何避免XRUN回调跳过

Question

在设置了QjackCtrl和Arour之后，我可以记录得很好，但是XRUN回调跳过是很烦人的。

这是我的QjackCtrl配置：

在日志中我看到：

18:37:22.041 XRUN callback (97).
18:37:22.793 XRUN callback (42 skipped).
18:37:24.794 XRUN callback (111 skipped).
18:37:26.795 XRUN callback (111 skipped).
18:37:28.796 XRUN callback (111 skipped).
18:37:30.798 XRUN callback (75 skipped).
18:38:45.359 XRUN callback (552).
Mon Oct 20 18:38:45 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Running
Mon Oct 20 18:38:45 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:38:45 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:38:46 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Triggered
Mon Oct 20 18:38:46 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:38:46 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Triggered
Mon Oct 20 18:38:46 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
18:38:46.833 XRUN callback (3 skipped).
Mon Oct 20 18:38:46 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Triggered
Mon Oct 20 18:38:46 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:38:46 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:38:46 2014: ERROR: JackEngine::XRun: client = PulseAudio JACK Sink was not finished, state = Triggered
Mon Oct 20 18:38:46 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
18:38:48.834 XRUN callback (23 skipped).
18:40:28.031 XRUN callback (580).
Mon Oct 20 18:40:28 2014: ERROR: JackEngine::XRun: client = PulseAudio JACK Sink was not finished, state = Running
Mon Oct 20 18:40:28 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
18:40:28.884 XRUN callback (1 skipped).
Mon Oct 20 18:40:28 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Triggered
Mon Oct 20 18:40:28 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = PulseAudio JACK Sink was not finished, state = Running
Mon Oct 20 18:40:29 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = PulseAudio JACK Sink was not finished, state = Triggered
Mon Oct 20 18:40:29 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = PulseAudio JACK Sink was not finished, state = Triggered
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client PulseAudio JACK Source finished after current callback
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Running
Mon Oct 20 18:40:29 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = PulseAudio JACK Sink was not finished, state = Running
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = PulseAudio JACK Source was not finished, state = Triggered
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Triggered
Mon Oct 20 18:40:29 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Triggered
Mon Oct 20 18:40:29 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:40:29 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
Mon Oct 20 18:40:29 2014: ERROR: JackEngine::XRun: client = ardour was not finished, state = Triggered
Mon Oct 20 18:40:29 2014: ERROR: JackAudioDriver::ProcessGraphAsyncMaster: Process error
18:40:30.885 XRUN callback (32 skipped).
18:40:32.887 XRUN callback (89 skipped).

什么是XRUN回调跳过？我怎样才能解决这些问题？

使用低延迟内核运行Ubuntu14.04：

$ uname -a
Linux laptop 3.13.0-38-lowlatency #65-Ubuntu SMP PREEMPT Thu Oct 9 12:04:28 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux

Answer 1

再次遇到这种情况，并最终得到了正确的答案，为什么xrun会发生。

来自JACKS页面：

指定插孔进程()调用之间的帧数。B这个值必须是2/b的幂，默认值是1024。如果您需要较低的延迟时间，请将-p设置为尽可能低，而不需要看到xrun。更大的周期大小会产生更高的延迟，但使xrun不太可能运行。以秒为单位的千斤顶捕获延迟是周期除以速率。

您需要将sample rate、frames/period和periods/buffer设置为正确。下面是usb设备的最佳选择。

(Frames [or buffer] / Sample Rate ) * Periods = Latency in ms

( 16 / 48000 ) * 3 = 1
( 32 / 48000 ) * 3 = 2
( 64 / 48000 ) * 3 = 4
( 128 / 48000 ) * 3 = 8
( 256 / 48000 ) * 3 = 16
( 512 / 48000 ) * 3 = 32
( 1024 / 48000 ) * 3 = 64
( 2048 / 48000 ) * 3 = 128
( 32 / 96000 ) * 3 = 1
( 64 / 96000 ) * 3 = 2
( 128 / 96000 ) * 3 = 4
( 256 / 96000 ) * 3 = 8
( 512 / 96000 ) * 3 = 16
( 1024 / 96000 ) * 3 = 32
( 2048 / 96000 ) * 3 = 64
( 64 / 192000 ) * 3 = 1
( 128 / 192000 ) * 3 = 2
( 256 / 192000 ) * 3 = 4
( 512 / 192000 ) * 3 = 8
( 1024 / 192000 ) * 3 = 16
( 2048 / 192000 ) * 3 = 32

我选了最优的，所有的都在这里：http://wiki.linuxaudio.org/wiki/list_的_杰克_框架_句号_设置_理想化_为_usb_接口