如何从命令行检查(使用ALSA插件创建的虚拟设备的)音频线输出是否有音频信号?并检查信号强度吗?
我找到了使用“ sox”工具(sox man)的解决方案。我可以使用此答案中建议的方法(将声音输出发送到应用程序和扬声器)在alsa虚拟设备调用“回送”中获取信号,同时还将其发送到输出设备,然后使用sox查找是否存在信号它的优点是:
sox -b 16 -t alsa hw:Loopback,1,0 -r 48000 -n stat
(-b-> 16位信号,-t(alsa hw:Loopback,1,0)->给我信号的虚拟设备,-r 48000->采样频率和-n stat->分析信号)
该命令给出如下输出:
Input File : 'hw:Loopback,1,0' (alsa)
Channels : 2
Sample Rate : 48000
Precision : 16-bit
Sample Encoding: 16-bit Signed Integer PCM
In:0.00% 00:00:02.47 [00:00:00.00] Out:115k [-=====|=====-] Hd:3.9 Clip:0
Samples read: 229376
Length (seconds): 2.389333
Scaled by: 2147483647.0
Maximum amplitude: 0.630951
Minimum amplitude: -0.630981
Midline amplitude: -0.000015
Mean norm: 0.159916
Mean amplitude: -0.004383
RMS amplitude: 0.198459
Maximum delta: 1.176422
Minimum delta: 0.000000
Mean delta: 0.223984
RMS delta: 0.278537
Rough frequency: 10721
Volume adjustment: 1.585
当您收到信号时,如无信号时:
Input File : 'hw:Loopback,1,0' (alsa)
Channels : 2
Sample Rate : 48000
Precision : 16-bit
Sample Encoding: 16-bit Signed Integer PCM
In:0.00% 00:02:23.70 [00:00:00.00] Out:6.89M [ | ] Clip:0
Samples read: 13787136
Length (seconds): 143.616000
Scaled by: 2147483647.0
Maximum amplitude: 0.000000
Minimum amplitude: 0.000000
Midline amplitude: 0.000000
Mean norm: 0.000000
Mean amplitude: 0.000000
RMS amplitude: 0.000000
Maximum delta: 0.000000
Minimum delta: 0.000000
Mean delta: 0.000000
RMS delta: 0.000000
Rough frequency: 0
可以在(Sox手册页)中找到“ -n stat”工具的含义。
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