我正在尝试在 2 个树莓派之间传输低延迟音频。gstreamer 和 ffmpeg 都对我造成了 2 秒以上的延迟。
我在本地玩过 Jack Audio，在单个 pi 上似乎很有希望。我可以在本地将麦克风输入路由到扬声器，这几乎是瞬时的。
但是，我一直无法使用 Netjack 在设备之间进行路由。
# ON SERVER
jackd -P70 -p16 -t2000 -dalsa -dhw:1 -p128 -n3 -r44100 -s
# ON CLIENT
jackd -v -R -P70 -dnetone -i1 -o1 -I0 -O0 -r44100 -p128 -n3
# ON SERVER
jack_netsource -H < ip address of client >
jack_lsp # list availible connection ports
>system:capture_1
>system:playback_1
>system:playback_2
>netjack:capture_1
>netjack:capture_2
>netjack:capture_3
>netjack:playback_1
>netjack:playback_2
>netjack:playback_3
jack_connect system:capture_1 system:playback_1 # this works
jack_connect system:capture_1 netjack:playback_1 # this doesn't work :(
我从这里提取的大多数启动选项http://wiki.linuxaudio.org/wiki/raspberrypi#using_jack。老实说，我真的不知道他们在做什么。
客户端 jackd 输出显示如下消息
Jack: data not valid
Jack: data not valid
Jack: JackSocketServerChannel::Execute : fPollTable i = 1 fd = 6
Jack: JackRequest::Notification
Jack: JackEngine::ClientNotify: no callback for notification = 3
Jack: JackEngine::ClientNotify: no callback for notification = 3
netxruns... duration: 139ms
Jack: JackSocketServerChannel::Execute : fPollTable i = 1 fd = 6
Jack: JackRequest::Notification
Jack: JackEngine::ClientNotify: no callback for notification = 3
Jack: JackEngine::ClientNotify: no callback for notification = 3
服务器 jack_netsource 输出看起来像
current latency 114
current latency 20
current latency 27
current latency 29
current latency 48
current latency 23
current latency 33
current latency 28
current latency 41
current latency 84
current latency 44
服务器jackd输出看起来像
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackEngine::XRun: client = netjack was not finished, state = Triggered
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackAudioDriver::ProcessGraphAsyncMaster: Process error
JackEngine::XRun: client = netjack was not finished, state = Triggered
JackEngine::XRun: client = netjack was not finished, state = Triggered
我相信-dnetone标志表明使用 Netjack2。Netjack 1，我已经尝试使用该-dnet标志导致Not Connected来自 jack_netsource 的一条消息，并且：
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: CatchHost fd = 5 err = Resource temporarily unavailable
Jack: JackSocketServerChannel::Execute : fPollTable i = 1 fd = 6
从客户端jackd。