Audio Output Quality is 16 KHz on v2

info about ReSpeaker series products

Moderators: lily.li, violet, seth.welday

carlos
Pre-kindergarten
Pre-kindergarten
Posts: 4
Joined: Mon Jul 30, 2018 1:27 am

Audio Output Quality is 16 KHz on v2

Post by carlos » Mon Jul 30, 2018 1:30 am

I just received my ReSpeaker Mic Array v2 and the voice recognition is amazing.
However I noticed that the audio output is very dump / low quality.

I tested the output speaker and cable with my smartphone (same music) and it was better.

From my analyze I found that the hardware only supports 24-bit 16 KHz as output.

For the audio output, to have an acceptable quality 48 KHz would be good, I guess due to UAC 1.0 and DSP Algorithms this has to be limited at some point, but 16 KHz is a really poor output.

Issue also created here: https://github.com/respeaker/usb_4_mic_array/issues/10

bill.yu
Elementary-5
Elementary-5
Posts: 597
Joined: Mon Apr 02, 2018 11:05 am

Re: Audio Output Quality is 16 KHz on v2

Post by bill.yu » Mon Jul 30, 2018 9:49 am

Hi there
The Max Sample Rate is 16Khz. We suggest to update the firmware to 1_channel_firmware.bin by following http://wiki.seeedstudio.com/ReSpeaker_M ... e-firmware. the output audio will be Processed audio for ASR. thanks.

Bill

carlos
Pre-kindergarten
Pre-kindergarten
Posts: 4
Joined: Mon Jul 30, 2018 1:27 am

Re: Audio Output Quality is 16 KHz on v2

Post by carlos » Tue Jul 31, 2018 2:07 am

I already updated my Mic Array to the 1 channel firmware.
So does this mean there is no plan to raise the audio output quality / sample rates?

This would mean the mic array would always provide very poor audio output (even on good speakers).

The WM8960 Audio Chip on the Mic Array can handle these Samplerates: 8, 11.025, 12, 16, 22.05, 24, 32, 44.1, 48 KHz
The XVF3000 Chip can handle Samplerates: Up to 48kHz sample rate


Just for comparison:
ReSpeaker MicArray v2 Quality - 16 KHz/24 bit
CD Quality - 44,1 KHz/16 bit
DVD Quality - 48 KHz / 16 bit
Hi-Res Audio Quality - 96 kHz/24 bit
Studio Quality - 192 KHz/24 bit


UPDATE: Bill I think you misunderstood me, I'm talking about audio output (speaker) not audio input (microphones)

bill.yu
Elementary-5
Elementary-5
Posts: 597
Joined: Mon Apr 02, 2018 11:05 am

Re: Audio Output Quality is 16 KHz on v2

Post by bill.yu » Fri Aug 03, 2018 9:11 am

Hi there, I talked with the software engineer and the 16Khz is related with algorithm. Current we do not have plan to update the algorithm. thanks for understanding.

Bill

virajk
Pre-kindergarten
Pre-kindergarten
Posts: 1
Joined: Mon Jun 03, 2019 3:26 pm

Re: Audio Output Quality is 16 KHz on v2

Post by virajk » Mon Jun 03, 2019 5:19 pm

Hi, is there an update on this? Is true 48khz sample rate supported on audio output? I am fine if you can provide a firmware with proper 48kHz playback support without any algo processing. Is it possible?

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

Re: Audio Output Quality is 16 KHz on v2

Post by fastjack79 » Sun Jun 30, 2019 6:57 pm

Hey!

I've tested the 48kHz firmwares (both 1 channel and 6 channels):
- The 6 channels version just output saturated sounds (not usable).
- The 1 channel version output 48kHz rate (clear audio) but with strange "sh" artifacts rendering poor audio quality.

Is it something that can be improved?

Are you guys at Seeed still working on the ReSpeaker Mic Array v2?

bill.yu
Elementary-5
Elementary-5
Posts: 597
Joined: Mon Apr 02, 2018 11:05 am

Re: Audio Output Quality is 16 KHz on v2

Post by bill.yu » Mon Jul 01, 2019 12:44 pm

Hi there~,

I just tested with 48k_1_channel_firmware.bin and 48k_6_channels_firmware.bin. Both of them work well.

1. please try to burn the firmware once again.
2. If the issue is not solved, please use audacity to record the audio files and posted it here. thanks.

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

Re: Audio Output Quality is 16 KHz on v2

Post by fastjack79 » Mon Jul 01, 2019 10:58 pm

Hey!

I tested the latest 48Khz firmwares and did not ear any changes.

Here is the file I'm playing (loop-test.wav) and the record from the playback channel of the ReSpeaker (mic.wav) with the 48khz_6channels_firmware.
Please download files here (too big for forum quota): https://wetransfer.com/downloads/ce1c7d ... 000/3d4116

I'm on a Raspberry Pi 3B+ with the latest Raspbian Stretch OS (fully updated).

Here is the verbose aplay output: aplay -Dplughw:ArrayUAC10 loop-test.wav -vv

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

Hope this helps. Tell me if you need more info.

Thanks for your help :)

bill.yu
Elementary-5
Elementary-5
Posts: 597
Joined: Mon Apr 02, 2018 11:05 am

Re: Audio Output Quality is 16 KHz on v2

Post by bill.yu » Tue Jul 02, 2019 11:00 am

Hi there~,

Here is my hardware connection and audacity result.

1. First, i run the below command to play music through terminal.
2. Then i use the audacity to record the audio. You can say something. You can stop the recording later on.
3. You can select the channel0 with solo mode to play back the processed audio. thanks.

Code: Select all

aplay -D plughw:1,0 -f cd  loop-test.wav
Image

Image

https://github.com/SeeedDocument/forum_ ... _files.zip

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

Re: Audio Output Quality is 16 KHz on v2

Post by fastjack79 » Tue Jul 02, 2019 6:58 pm

Hi!

Thank you for your feedback.

After more investigation, I think I found the cause of the saturated audio playback with the 48Khz 6 channels firmware.

The culprit seems to be the USB bandwidth.

The saturated audio playback only happens when I capture the 6 channels mic input during playback.

Either the cable or the Raspberry Pi USB bandwidth cannot cope with all the 6 channels capture and 2 channels playback in 48Khz. Since your 6 channels Audacity file is correct and without saturation, the real culprit seems to be the USB cable.

Can you confirm this by checking the output of

Code: Select all

cat /proc/asound/ArrayUAC10/stream0
on your setup to see if you have "full speed" or "high speed" :
Here is my output: SEEED ReSpeaker 4 Mic Array (UAC1.0) at usb-3f980000.usb-1.1.2, full speed : USB Audio

There are however strange audio playback artifacts on specific song lyrics (saturation on "sh" and "ss" sounds, "share", "strong") that I do not ear when playing the same audio file on Windows or with the 16khz firmwares.

The AEC with the 48khz firmwares are also a lot worse (almost inexistant).

Is it something that can be improved?

Thanks you again for your help.

Post Reply