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Audio Clipping

Homer1952
Posts: 8
Joined: Wed Aug 19, 2020 11:21 am

Audio Clipping

#1

Unread post by Homer1952 »

Listening to my Discovery using v3026 & getting audio clipping on LSB 80M. I have had this issue many months ago, posted the issue on the IO group & then it seemed to just disappear. When this happens the "Audio:" gage (latency??) at the bottom left of the display goes well above 100ms. There are time it gets to +350ms. This clipping does not happen with other s/w. I have tried 2 different USB ports (hub & no hub) to no avail. When the "latency" is below ~60ms, then audio is fine. Thoughts? Bob W8RMV
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Homer1952
Posts: 8
Joined: Wed Aug 19, 2020 11:21 am

Re: Audio Clipping

#2

Unread post by Homer1952 »

To add more to my confusion, if I record the QSO, it sounds clean when played back thru VLC. Listening to it live is pretty painful.

-Bob W8RMV

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Simon G4ELI
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Joined: Thu Aug 06, 2020 7:27 am
Location: Mawnan Smith
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Re: Audio Clipping

#3

Unread post by Simon G4ELI »

Do not turn the visual gain down so much. Leave it at 0.
Simon Brown :shock:
www.sdr-radio.com

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jdow
Posts: 393
Joined: Mon Aug 10, 2020 8:17 pm

Re: Audio Clipping

#4

Unread post by jdow »

Something called "visual gain" should not affect the audio, should it?
{O.O}

Homer1952
Posts: 8
Joined: Wed Aug 19, 2020 11:21 am

Re: Audio Clipping

#5

Unread post by Homer1952 »

I've tried moving the VG to every step, to no avail.
I've turned off the AGC & tried several ATT settings, to no avail.
Tried fast med & slow AGC, to no avail.
I've uninstalled & reinstalled the latest Console, to no avail.

To my ears it sounds "like" clipping distortion from a bad AGC or poor noise blanker or if the audio input is o/l the preamp in the computer.

Maybe this is normal, but when I mute the speaker on Console, Audio: is at 0ms, but I can still see audio activity on the volume control.
CPU is at <2% & Size: 523MB.

Compooter is an I7 32GB ram running W10 64bit & the very latest updates & drivers.

I've a DP HF+ & a RSP2 I may try later. But when I run SDR# the Discovery runs fine. ???

-Bob W8RMV

Homer1952
Posts: 8
Joined: Wed Aug 19, 2020 11:21 am

Re: Audio Clipping

#6

Unread post by Homer1952 »

Update.
I did find a new Realtek driver & installed that. I also looked at an EQ app ( for my old fart ears) I have on the PC & redid the EQ starting at -20dB upward, instead of 0dB. I retuned the EQ option in Console also. I think all those dB's were adding up to exceeding 0dB into the digital preamp of the computer & causing the distortion.
The Audio: gage is now running much lower, but I am still not sure what a good or preferred ms is as there is very little guidance on any of these settings/observations. Why the Audio gage goes from 40ms to 150ms is a mystery when the signal doesn't change much as the AGC takes control. Changing the visual gain will definitely change the audio output level to the computer.

The audio is much better now but still have an occasional pop now & then from some on 80M LSB. Still a mystery SDR# seemed to deal with the original settings.

I will update as necessary, thanx for the comments.

-Bob W8RMV

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G3TDJ
Posts: 10
Joined: Mon Jan 25, 2021 1:24 pm

Re: Audio Clipping

#7

Unread post by G3TDJ »

Bob....this might be some help in your diagnosis of the "audio clipping" anomaly.

I can "force" audio clipping/stuttering, accompanied by high latency outside the range of the SDR Console audio bar graph by just changing the audio sink.

My normal audio output uses RealTek HD audio and is fine. But if I change the audio sink to a Logitech H340 USB headset the SDR Console audio bar graph increases rapidly from the normal 50 mS +/- to > 200 mS and audio clipping/stuttering commences. The symptom is identical in Windows 10 and Windows 7

If I change the audio sink to a Logitech H800 wireless headset the audio output is perfect.

I have traced the reason for the Logitech H340 clipping/stuttering anomaly:

Looking at Playback > Properties > Advanced in the Windows Sound applet, (mmsys.cpl), the Default Format for all audio sinks that perform well without audio clipping/stuttering in SDR Console (3.026) is 16-bit, 48000 Hz (DVD Quality) - (generally the Default Format sample rate can be changed from this menu).

However for the troublesome Logitech H340 headset the Default Quality is 44100 Hz and there are no other sample rate choices available. The driver in use is the generic Windows USB Audio driver and so far I have not been able to locate a Logitech driver.

So for your problem with audio clipping it might be worth checking that the Default Quality for your Realtek audio sink is set to 48000 Hz. In my case the log file shows where SDR Console tries to resample the audio output to 48000 Hz when the troublesome H340 headset is used.

I can confirm your finding that SDR# does not suffer the same audio anomaly using the Logitech H340 headset and the same SDR hardware used for the SDR Console testing.

Andy G3TDJ

jdow
Posts: 393
Joined: Mon Aug 10, 2020 8:17 pm

Re: Audio Clipping

#8

Unread post by jdow »

20 ms is probably a little tight. 40 ms is probably OK. 100 ms or even longer may be required in some situations.

Be careful with your audio chain, especially when playing with an equalizer. (They DO help old ears, don't they?)

One way to check it is to find an external audio source, preferably one that is a little hot. Once it's level is setup without distortion then setup the level on SDRC to more or less match. FWIW I have gains set to unity except for the individual sources, which are set low, and have the equalizer external to the PC. That way I can feed speakers for other folks listening and use cans (Bose QC-15) and an equalizer for my very drastic equalizer setup.

{^_^}

Homer1952
Posts: 8
Joined: Wed Aug 19, 2020 11:21 am

Re: Audio Clipping

#9

Unread post by Homer1952 »

Andy,
Thank you for the comments. I have tried several bit settings & qualities in sound card device settings & could not really discern a difference SQ or latency. The audio doesn't seem to change much. The audio meter seems to start at ~70ms & then walks up to ~150ms and then back down and back again. But the clipping has gone away, for now. I took a look at the attached youtube & interestingly it seems to be locked a 114ms. No variation. I never see that.


-Bob W8RMV

ps- when I look at the audio settings in SDRC playback devices I see 48,000 rate 2 ch & 32bits for my Realtek Audio, but my audio card only supports 16 & 24bit. according to W10 sound devices

jdow
Posts: 393
Joined: Mon Aug 10, 2020 8:17 pm

Re: Audio Clipping

#10

Unread post by jdow »

That buffer is an elastic affair. If it gets very high, like a second for example, then there is is a problem.

{^_^}

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