On Thu, 10 Aug 2017, at 02:05 AM, Per Gunnarsson wrote: > Hello! > > I bought a microphone (MICO from Trust) and plugged it into the 3.5 jack > of my computer. > > My OS is Debian testing on an old Acer desktop. > > To begin, I had a lot of static noise which was removed when I tried: > > pactl load-module module-echo-cancel aec_method=webrtc > > without really understanding what I did. > > I have looked into pactl list and see this: > > Source #2 > State: RUNNING > Name: alsa_input.pci-0000_00_14.2.analog-stereo > Description: Built-in Audio Analog Stereo > Driver: module-alsa-card.c > Sample Specification: s16le 2ch 48000Hz > Channel Map: front-left,front-right > Owner Module: 8 > Mute: no > Volume: front-left: 21845 / 33% / -28.63 dB, front-right: > 21845 / 33% / -28.63 dB > balance 0.00 > Base Volume: 5841 / 9% / -63.00 dB > Monitor of Sink: n/a > Latency: 2301 usec, configured 66666 usec > Flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME > LATENCY > Properties: > alsa.resolution_bits = "16" > device.api = "alsa" > device.class = "sound" > alsa.class = "generic" > alsa.subclass = "generic-mix" > alsa.name = "ALC662 rev1 Analog" > alsa.id = "ALC662 rev1 Analog" > alsa.subdevice = "0" > alsa.subdevice_name = "subdevice #0" > alsa.device = "0" > alsa.card = "1" > alsa.card_name = "HDA ATI SB" > alsa.long_card_name = "HDA ATI SB at 0xfeb40000 irq 16" > alsa.driver_name = "snd_hda_intel" > device.bus_path = "pci-0000:00:14.2" > sysfs.path = > "/devices/pci0000:00/0000:00:14.2/sound/card1" > device.bus = "pci" > device.vendor.id = "1002" > device.vendor.name = "Advanced Micro Devices, Inc. > [AMD/ATI]" > device.product.id = "4383" > device.product.name = "SBx00 Azalia (Intel HDA)" > device.form_factor = "internal" > device.string = "front:1" > device.buffering.buffer_size = "384000" > device.buffering.fragment_size = "192000" > device.access_mode = "mmap+timer" > device.profile.name = "analog-stereo" > device.profile.description = "Analog Stereo" > device.description = "Built-in Audio Analog Stereo" > alsa.mixer_name = "Realtek ALC662 rev1" > alsa.components = "HDA:10ec0662,10258100,00100101" > module-udev-detect.discovered = "1" > device.icon_name = "audio-card-pci" > Ports: > analog-input-front-mic: Front Microphone (priority: > 8500, not available) > analog-input-rear-mic: Rear Microphone (priority: 8200, > available) > analog-input-linein: Line In (priority: 8100, not > available) > Active Port: analog-input-rear-mic > Formats: > pcm > > > > > Source #7 > State: RUNNING > Name: alsa_input.pci-0000_00_14.2.analog-stereo.echo-cancel > Description: Built-in Audio Analog Stereo (echo cancelled with > Built-in Audio Analog Stereo) > Driver: module-echo-cancel.c > Sample Specification: float32le 1ch 32000Hz > Channel Map: mono > Owner Module: 31 > Mute: no > Volume: mono: 21845 / 33% > balance 0.00 > Base Volume: 65536 / 100% > Monitor of Sink: n/a > Latency: 9221 usec, configured 66666 usec > Flags: HW_MUTE_CTRL LATENCY > Properties: > device.master_device = > "alsa_input.pci-0000_00_14.2.analog-stereo" > device.class = "filter" > device.intended_roles = "phone" > device.description = "Built-in Audio Analog Stereo (echo > cancelled with Built-in Audio Analog Stereo)" > device.icon_name = "audio-input-microphone" > Formats: > pcm > > Now I wonder why there is a difference in sample specification between > the sources. > > > Without echo cancellation: > > Sample Specification: s16le 2ch 48000Hz > > > With echo cancellation: > > Sample Specification: float32le 1ch 32000Hz That's just the default (for voice, higher sample rates aren't really necessary). You can set the rate as a module argument, or set use_master_format=true to just use what the source provides. Cheers, Arun
