Hi all,
Recently I have found a noise problem when using module-loopback.
I connected a alsa-source to a alsa-sink with module-loopback
the data from alsa-source is actually sine-wave (rate=44100,
format=s16le, channels=2)
I found that in the adjust_rates function, if I comment
"pa_sink_input_set_rate",
there is no noise, but if I uncomment "pa_sink_input_set_rate",
problem appears.
Here is the setup log:
D/NMAudio ( 1797): [tid=1816] D: Negotiated format: pcm,
format.sample_format = "\"s16le\"" format.rate = "44100" format.channels ="
D/NMAudio ( 1797): [tid=1816] D: Resampler:
D/NMAudio ( 1797): [tid=1816] D: rate 44100 -> 44100 (method trivial)
D/NMAudio ( 1797): [tid=1816] D: i_ss.format=s16le, o_ss.format=s16le
D/NMAudio ( 1797): [tid=1816] D: format s16le -> s16le (intermediate
s16le)
D/NMAudio ( 1797): [tid=1816] D: channels 2 -> 2 (resampling 2)
D/NMAudio ( 1797): [tid=1816] D: memblockq requested:
maxlength=33554432, tlength=0, base=4, prebuf=0, minreq=1 maxrewind=0
D/NMAudio ( 1797): [tid=1816] D: memblockq sanitized:
maxlength=33554432, tlength=33554432, base=4, prebuf=0, minreq=4 maxrewind=0
I/NMAudio ( 1797): [tid=1816] I: Created input 2 "(null)" on audioio.22
with sample spec s16le 2ch 44100Hz and channel map front-leftt
I/NMAudio ( 1797): [tid=1816] I: media.role = "abstract"
D/NMAudio ( 1797): [tid=1816] D: Negotiated format: pcm,
format.sample_format = "\"s16le\"" format.rate = "44100" format.channels ="
D/NMAudio ( 1797): [tid=1816] D: memblockq requested:
maxlength=33554432, tlength=0, base=4, prebuf=0, minreq=1 maxrewind=0
D/NMAudio ( 1797): [tid=1816] D: memblockq sanitized:
maxlength=33554432, tlength=33554432, base=4, prebuf=0, minreq=4 maxrewind=0
I/NMAudio ( 1797): [tid=1816] I: Created output 2 "(null)" on audioio.17
with sample spec s16le 2ch 44100Hz and channel map front-left
I/NMAudio ( 1797): [tid=1816] I: media.role = "abstract"
D/NMAudio ( 1797): [tid=1816] D: memblockq requested:
maxlength=33554432, tlength=33554432, base=4, prebuf=0, minreq=0 maxrewind=0
D/NMAudio ( 1797): [tid=1816] D: memblockq sanitized:
maxlength=33554432, tlength=33554432, base=4, prebuf=0, minreq=4 maxrewind=0
I/NMAudio ( 1797): [tid=1816] I: Adding 35280 bytes of silence to queue
I/NMAudio ( 1797): [tid=1844] I: Max request changed
D/NMAudio ( 1797): [tid=1844] D: Requesting rewind due to uncorking
D/NMAudio ( 1797): [tid=1844] D: Requested to rewind 5292 bytes.
D/NMAudio ( 1797): [tid=1844] D: Processing rewind...
D/NMAudio ( 1797): [tid=1844] D: Processing rewind...
D/NMAudio ( 1797): [tid=1844] D: Rewound 4140 bytes.
I/NMAudio ( 1797): [tid=1816] I: Loaded "module-loopback" (index: #7;
argument: "loopbackid=1722 source=audioio.17 sink=audioio.22
-----------> before this line, the rate of sink-input was not adjusted,
everything is fine, no noise appears
D/NMAudio ( 1797): [tid=1816] D: Loopback overall latency is 19.46 ms +
182.97 ms + 2.67 ms = 205.02 ms (at the base rate: 205.02 ms,)
D/NMAudio ( 1797): [tid=1816] D: Latency difference: 5.02 �± 1.00 ms,
rate difference: 0 Hz
D/NMAudio ( 1797): [tid=1816] D: [audioio.22] Updated sampling rate to
44200 Hz.
-----------> after 10 second, the rate of sink-input was adjusted, noise
comes out.
I have been playing around all the new rate variables, any value
that do not equals to 44100 will make audio noise.
That looks very strange to me, so I`m asking if anyone have met this
problem before ?
Thanks !
BR,
Lixin
