the diving wave

[froe]

Hi.

Why does my wave "dive"?

NOTE that the large sawtooth drops are from me adjusting the volume during recording, but the same dive occurs in Ardour without the volume adjustment.

I recorded it from sooperlooper, I tried both with the jack_render thingie, and ardour, but the results are the same, it dives....
please help me understand and adjust.

[CrocoDuck]

That's a pretty weird wave, I remember seeing something like that when using my very old soundblaster in the 90s, but on a smaller scale. Is it happening when you record a completely software audio source? Try to record the sound output of a synthesizer program. Maybe it is best to try record a sine wave first (maybe 1 kHz) and a white noise sequence second. You can generate signals with Baudline. With jack, it should be easy to connect Baudline output to some recorder input.

There are two cases (I think):

• Something weird on your data streams is going on and numbers are being added to them.
• Your soundcard inputs are not very well DC decoupled (or faulty in other ways) and when you record also some varying bias voltage is recorded as well. Not sure why you should see something like that in Superlooper tho.

If we see the dive also when recording from a software signal generator I would guess there is something wrong on the software side. Let's have a ritualistic look at your hardware. Give the output of

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lspci -vnn

[folderol]

That's fairly typical of rectifying action in the analog world. The drop pretty closely follows the positive going peaks of the waveform. For it to limit around the 0V point would suggest a 'top' transistor in a push-pull circuit not being driven.

In a purely software world it suggests a bit of dodgy math. Have you changed/upgraded anything recently?

[froe]

Thank you CrocoDuck!

I tried recording from an lmms synth into superlooper, and the waveform looked fine!

I then moved on to just record the microphone, and yes, there were the same problem, it were under the line.

I then adjusted some settings in the alsamixer, and it now seems to behave as it should.

I will go back and try to replicate the settings that made the problem, cos now I don't even remember what I did to fix it....

Froe

[froe]

Now it's not working anymore. It seems to be something with my soundcard(?):

Here's the output from lspci -vnn:

00:1b.0 Audio device [0403]: Intel Corporation NM10/ICH7 Family High Definition Audio Controller [8086:27d8] (rev 02)
Subsystem: Toshiba America Info Systems Device [1179:ff02]
Flags: bus master, fast devsel, latency 0, IRQ 45
Memory at dc440000 (64-bit, non-prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: snd_hda_intel


The wave "centre-line" moves like this when I adjust the DIGITAL slider in alsamixer while recording.
Top wave with microphone and sound, the one below, nothing connected.
Setting the DIGITAL-slider to 0 makes it go dead centre, but no sound will be recorded, adjusting it up will make the wave dive more and more, but also make the signal "louder.....

WHY?

I will try recording thru a Zoom H4 later.

[CrocoDuck]

Uhm... interesting. Seems the problem is where the card fills digital data streams. Give us also the output of

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aplay -l
arecord -l

and if you can also the complete list of alsamixer controls.

[froe]

Works with the Zoom H4, so 100% it's the soundcard.

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aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC861-VD Analog [ALC861-VD Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
 
arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: Intel [HDA Intel], device 0: ALC861-VD Analog [ALC861-VD Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

[CrocoDuck]

I wonder whether we just need to specify some configuration detail for ALSA to handle the chipset (ALC861-VD Analog).

Do you have a alsa-base.conf? Repost:

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cat /etc/modprobe.d/alsa-base.conf

[froe]

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# autoloader aliases
install sound-slot-0 /sbin/modprobe snd-card-0
install sound-slot-1 /sbin/modprobe snd-card-1
install sound-slot-2 /sbin/modprobe snd-card-2
install sound-slot-3 /sbin/modprobe snd-card-3
install sound-slot-4 /sbin/modprobe snd-card-4
install sound-slot-5 /sbin/modprobe snd-card-5
install sound-slot-6 /sbin/modprobe snd-card-6
install sound-slot-7 /sbin/modprobe snd-card-7

# Cause optional modules to be loaded above generic modules
install snd /sbin/modprobe --ignore-install snd $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-ioctl32 ; /sbin/modprobe --quiet --use-blacklist snd-seq ; }
#
# Workaround at bug #499695 (reverted in Ubuntu see LP #319505)
install snd-pcm /sbin/modprobe --ignore-install snd-pcm $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-pcm-oss ; : ; }
install snd-mixer /sbin/modprobe --ignore-install snd-mixer $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-mixer-oss ; : ; }
install snd-seq /sbin/modprobe --ignore-install snd-seq $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; /sbin/modprobe --quiet --use-blacklist snd-seq-oss ; : ; }
#
install snd-rawmidi /sbin/modprobe --ignore-install snd-rawmidi $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq-midi ; : ; }
# Cause optional modules to be loaded above sound card driver modules
install snd-emu10k1 /sbin/modprobe --ignore-install snd-emu10k1 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-emu10k1-synth ; }
install snd-via82xx /sbin/modprobe --ignore-install snd-via82xx $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist snd-seq ; }

# Load saa7134-alsa instead of saa7134 (which gets dragged in by it anyway)
install saa7134 /sbin/modprobe --ignore-install saa7134 $CMDLINE_OPTS && { /sbin/modprobe --quiet --use-blacklist saa7134-alsa ; : ; }
# Prevent abnormal drivers from grabbing index 0
options bt87x index=-2
options cx88_alsa index=-2
options saa7134-alsa index=-2
options snd-atiixp-modem index=-2
options snd-intel8x0m index=-2
options snd-via82xx-modem index=-2
options snd-usb-audio index=-2
options snd-usb-caiaq index=-2
options snd-usb-ua101 index=-2
options snd-usb-us122l index=-2
options snd-usb-usx2y index=-2
# Ubuntu #62691, enable MPU for snd-cmipci
options snd-cmipci mpu_port=0x330 fm_port=0x388
# Keep snd-pcsp from being loaded as first soundcard
options snd-pcsp index=-2
# Keep snd-usb-audio from being loaded as first soundcard
options snd-usb-audio index=-2
# Prevent snd-aloop from being loaded as first soundcard
options snd-aloop index=-2
#test
alias snd-card-0 snd-hda-intel
options snd-hda-intel model=auto

[folderol]

Still following this (although I can't think of any more suggestions).
When you've got it sorted you need to compose something with 'The Diving Wave' as the title

[CrocoDuck]

Sorry I am very busy at work these days and I forgot about the thread. That seems the standard Ubuntu configuration. Do you confirm you did not edit it?

There aren't suggested options for your codec, but I found a bug report that might be relevant. Let's add these lines at the end of /etc/modprobe.d/alsa-base.conf:

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alias snd-card-0 snd-hda-intel
options snd-hda-codec-realtek index=-2