malformed (wrongly scaled?) waveform with input_alsa about libvisual HOT 8 CLOSED

Did you compare this with PulseAudio input? The DFT is a linear transform, so DFT-based visualizations should also exhibit the same problem if input waveforms are incorrectly scaled.

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Chong Kai Xiong [email protected] schrieb:

Did you compare this with PulseAudio input? The DFT is a linear
transform, so DFT-based visualizations should also exhibit the same
problem if input waveforms are incorrectly scaled.

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Reply to this email directly or view it on GitHub:
#4 (comment)

no, only input_alsa and input_debug work.

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PulseAudio works for me, but I have to use pavucontrol to be able to redirect and capture output audio streams.

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it seems input_alsa needs a complete facelift and VisParam support selection of different hardwares. https://github.com/mumble-voip/mumble/blob/master/src/mumble/ALSAAudio.cpp could serve as example, it looks quite clean.

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I really can't see anything wrong with the input signal from ALSA. If there is any incorrect scaling, it has to be elsewhere in lv_audio.c where the samples are converted.

If you're using lv_scope to check the waveforms, be aware that peak amplitudes will show up at 1/4 and 3/4 of the display height. They will not reach the top or bottom of the display.

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Chong Kai Xiong [email protected] schrieb:

I really can't see anything wrong with the input signal from ALSA. If
there is any incorrect scaling, it has to be elsewhere in lv_audio.c
where the samples are converted.

If you're using lv_scope to check the waveforms, be aware that peak
amplitudes will show up at 1/4 and 3/4 of the display height. They will
not reach the top or bottom of the display.

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Reply to this email directly or view it on GitHub:
#4 (comment)

i suppose it's not even directly linked to lv but to my snd-hw driver. It offers various alsa devices (hw:, plugdev:, etc) and iirc i read something about software processing on one of them. I can't just hardcode another device into input_alsa.c, this doesn't work. I merely wanted to know if anyone else is experiencing this...

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Hmm.. I have other issues with the ALSA input plugin though. The most serious one is that It hangs after a while.

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issue seems to be fixed in cxx branch

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