Audio Output Quality is 16 KHz on v2

info about ReSpeaker series products

Moderators: lily.li, violet, seth.welday

bill.yu
Junior-7
Junior-7
Posts: 733
Joined: Mon Apr 02, 2018 11:05 am

Re: Audio Output Quality is 16 KHz on v2

Post by bill.yu » Wed Jul 03, 2019 2:30 pm

Hi there~

Here is my output. I am checking with software team about saturation on "sh" and "ss" sounds. thanks.

Code: Select all

pi@raspberrypi:~ $ cat /proc/asound/ArrayUAC10/stream0
SEEED ReSpeaker 4 Mic Array (UAC1.0) at usb-3f980000.usb-1.2, full speed : USB Audio

Playback:
  Status: Stop
  Interface 1
    Altset 1
    Format: S24_3LE
    Channels: 2
    Endpoint: 1 OUT (ASYNC)
    Rates: 48000, 48000, 48000

Capture:
  Status: Stop
  Interface 2
    Altset 1
    Format: S16_LE
    Channels: 6
    Endpoint: 2 IN (ASYNC)
    Rates: 48000, 48000, 48000
pi@raspberrypi:~ $

fastjack79
Pre-kindergarten
Pre-kindergarten
Posts: 8
Joined: Sun Jun 30, 2019 6:47 pm

Re: Audio Output Quality is 16 KHz on v2

Post by fastjack79 » Wed Jul 03, 2019 6:54 pm

Hi!

Using the 48k 6 channels firmware, the audio playback quality is degraded as soon as I start capturing.

Code: Select all

SEEED ReSpeaker 4 Mic Array (UAC1.0) at usb-3f980000.usb-1.1.3, full speed : USB Audio

Playback:
  Status: Stop
  Interface 1
    Altset 1
    Format: S24_3LE
    Channels: 2
    Endpoint: 1 OUT (ASYNC)
    Rates: 48000, 48000, 48000

Capture:
  Status: Stop
  Interface 2
    Altset 1
    Format: S16_LE
    Channels: 6
    Endpoint: 2 IN (ASYNC)
    Rates: 48000, 48000, 48000

Using usbtop, I can confirm that the USB bandwidth is nowhere near its max capacity (< 1MB/s).

Your setup is identical to mine but I am not able to get a clear audio playback during capture.

Here is what I do :

Session 1:

Code: Select all

aplay loop-test.wav -Dplughw:CARD=ArrayUAC10 -vv
Stdout:

Code: Select all

Playing WAVE 'loop-test.wav' : Signed 24 bit Little Endian in 3bytes, Rate 48000 Hz, Stereo
Plug PCM: Hardware PCM card 1 'ReSpeaker 4 Mic Array (UAC1.0)' device 0 subdevice 0
Its setup is:
  stream       : PLAYBACK
  access       : RW_INTERLEAVED
  format       : S24_3LE
  subformat    : STD
  channels     : 2
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 24
  buffer_size  : 24000
  period_size  : 6000
  period_time  : 125000
  tstamp_mode  : NONE
  tstamp_type  : MONOTONIC
  period_step  : 1
  avail_min    : 6000
  period_event : 0
  start_threshold  : 24000
  stop_threshold   : 24000
  silence_threshold: 0
  silence_size : 0
  boundary     : 1572864000
  appl_ptr     : 0
  hw_ptr       : 0
Audio is clear. Then I start the capture in another session.

Session 2:

Code: Select all

arecord -Dhw:CARD=ArrayUAC10 mic.wav -c 6 -r 48000 -f S16_LE -vv
Stdout:

Code: Select all

Recording WAVE 'mic.wav' : Signed 16 bit Little Endian, Rate 48000 Hz, Channels 6
Hardware PCM card 1 'ReSpeaker 4 Mic Array (UAC1.0)' device 0 subdevice 0
Its setup is:
  stream       : CAPTURE
  access       : RW_INTERLEAVED
  format       : S16_LE
  subformat    : STD
  channels     : 6
  rate         : 48000
  exact rate   : 48000 (48000/1)
  msbits       : 16
  buffer_size  : 24000
  period_size  : 6000
  period_time  : 125000
  tstamp_mode  : NONE
  tstamp_type  : MONOTONIC
  period_step  : 1
  avail_min    : 6000
  period_event : 0
  start_threshold  : 1
  stop_threshold   : 24000
  silence_threshold: 0
  silence_size : 0
  boundary     : 1572864000
  appl_ptr     : 0
  hw_ptr       : 0
Audio is degraded as soon as arecord starts capturing.

See the Audacity capture: https://we.tl/t-xi2h2gJpZZ

I have no clue why... Hope this helps your software engineers identify the cause. Tell me if you need more info.

Thanks again for your help.

bill.yu
Junior-7
Junior-7
Posts: 733
Joined: Mon Apr 02, 2018 11:05 am

Re: Audio Output Quality is 16 KHz on v2

Post by bill.yu » Wed Jul 10, 2019 10:14 am

Hi there~

The software team looked at the audio performance downgrade @ 48Khz. We do not have a good solution to solve this issue. thanks for understanding.

fastjack79
Pre-kindergarten
Pre-kindergarten
Posts: 8
Joined: Sun Jun 30, 2019 6:47 pm

Re: Audio Output Quality is 16 KHz on v2

Post by fastjack79 » Fri Jul 12, 2019 1:57 am

Hey!
Thank you for your feedback.

I understand completely that it can be challenging and you guys have already made an awesome product. This audio quality issue is the only thing preventing it from being perfect.

Instead of fixing the 48Khz 6 channels firmware audio downgrade issue, do you think you can improve the AEC of the 48Khz 1 channel firmware which is really bad comparing to the 16khz one (which is excellent) and fix the audio artifacts? The 1 channel 48Khz firmware does not have this audio downgrade issue (only strange audio artifacts which may be related). The AEC is almost inexistant though.

Is using 44100 Hz instead of 48000 Hz possible? Using 16bits instead of 24bits? Would it help?

Thanks for you help :) Really appreciate your support

Post Reply