Popping/Crackling noise during video playback over HDMI/DisplayPort audio

[Philipp91]

Hi,

I have an Nvidia graphics card (GeForce GTX 745) with the recommended driver (version 460.39-0ubuntu0.20.04.1), a monitor connected via DisplayPort and headphones connected to that monitor. When I play videos on YouTube, I sometimes hear popping/crackling noises, on average once per minute, though they can also occur within less than a second of each other. Between the noises I lose none of the important audio, i.e. I can still understand all the spoken words. Just the noises are annoying. When no audio/video is playing, there's also no noises.

The most salient characteristic of these noises is that they happen around visual cuts in the video, which first led me to believe that HDMI bandwidth might be the issue. But it doesn't happen on every cut, and sometimes it also happens in the middle of a scene without a cut. Now I'm thinking that video creators probably often cut the audio around scene cuts too, and sometimes they cut it off early, also maybe sometimes they mess with the audio in the middle of a scene to patch some background noise they accidentally recorded. My hypothesis is that this always happens when there's zero audio (as opposed to nobody talking, but the camera/microphone still recording some background noise level) in the stream and then the audio resumes, leading to a crack. Two experiments confirm that hypothesis so far:

• The cracks are always at (roughly) the same positions in the video. In fact I have a test video which crackles unusually much (and reproducibly) around minute 6:14.
• But when I have some background audio running (e.g. some music from Rhythmbox), there are no cracks at all.

Things I tried unsuccessfully:

• Firefox instead of Chrome.
• Other drivers for the graphics card (older versions 340 and 450 as well as Nouveau -- they have quite some issues with the display colors and fan control, but they also exhibit this audio issue).
• load-module module-udev-detect tsched=0 (https://askubuntu.com/questions/405071/ ... dio#444559)
• Commenting out load-module module-suspend-on-idle (https://ask.fedoraproject.org/t/my-audi ... -do/174/13)
• putting 10000000 or 0 into /sys/module/snd_hda_intel/parameters/power_save (and/or N into power_save_controller)

Each of these I tried with pulseaudio -k. As they had no noticeable effect whatsoever, I'm not sure if I tried those fixes in the right way though.

Things that work without any cracking noises:

• The same hardware and same YouTube video with Windows.
• Onboard audio instead of using audio over HDMI.

I'd appreciate any pointers. Is there a way to monitor what PulseAudio/ALSA are doing, especially whether they're entering any sleep states, quickly switching devices and back, or crashing due to some error and starting back up again very quickly?

Thanks!
Philipp

Code: Select all

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC891 Analog [ALC891 Analog]   <--- works fine
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 3: HDMI 0 [HDMI 0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 7: HDMI 1 [HDMI 1]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 8: HDMI 2 [HDMI 2]   <--- that's the one used for DisplayPort output and it produces the crackling noises
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 9: HDMI 3 [HDMI 3]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: NVidia [HDA NVidia], device 10: HDMI 4 [HDMI 4]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

$ aplay -L
default
    Playback/recording through the PulseAudio sound server
surround21
    2.1 Surround output to Front and Subwoofer speakers
surround40
    4.0 Surround output to Front and Rear speakers
surround41
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50
    5.0 Surround output to Front, Center and Rear speakers
surround51
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
null
    Discard all samples (playback) or generate zero samples (capture)
samplerate
    Rate Converter Plugin Using Samplerate Library
speexrate
    Rate Converter Plugin Using Speex Resampler
jack
    JACK Audio Connection Kit
oss
    Open Sound System
pulse
    PulseAudio Sound Server
upmix
    Plugin for channel upmix (4,6,8)
vdownmix
    Plugin for channel downmix (stereo) with a simple spacialization
sysdefault:CARD=PCH
    HDA Intel PCH, ALC891 Analog
    Default Audio Device
front:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    Front speakers
surround21:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    4.0 Surround output to Front and Rear speakers
surround41:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
dmix:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    Direct sample mixing device
dsnoop:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    Direct sample snooping device
hw:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    Direct hardware device without any conversions
plughw:CARD=PCH,DEV=0
    HDA Intel PCH, ALC891 Analog
    Hardware device with all software conversions
usbstream:CARD=PCH
    HDA Intel PCH
    USB Stream Output
hdmi:CARD=NVidia,DEV=0
    HDA NVidia, HDMI 0
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=1
    HDA NVidia, HDMI 1
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=2
    HDA NVidia, HDMI 2
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=3
    HDA NVidia, HDMI 3
    HDMI Audio Output
hdmi:CARD=NVidia,DEV=4
    HDA NVidia, HDMI 4
    HDMI Audio Output
dmix:CARD=NVidia,DEV=3
    HDA NVidia, HDMI 0
    Direct sample mixing device
dmix:CARD=NVidia,DEV=7
    HDA NVidia, HDMI 1
    Direct sample mixing device
dmix:CARD=NVidia,DEV=8
    HDA NVidia, HDMI 2
    Direct sample mixing device
dmix:CARD=NVidia,DEV=9
    HDA NVidia, HDMI 3
    Direct sample mixing device
dmix:CARD=NVidia,DEV=10
    HDA NVidia, HDMI 4
    Direct sample mixing device
dsnoop:CARD=NVidia,DEV=3
    HDA NVidia, HDMI 0
    Direct sample snooping device
dsnoop:CARD=NVidia,DEV=7
    HDA NVidia, HDMI 1
    Direct sample snooping device
dsnoop:CARD=NVidia,DEV=8
    HDA NVidia, HDMI 2
    Direct sample snooping device
dsnoop:CARD=NVidia,DEV=9
    HDA NVidia, HDMI 3
    Direct sample snooping device
dsnoop:CARD=NVidia,DEV=10
    HDA NVidia, HDMI 4
    Direct sample snooping device
hw:CARD=NVidia,DEV=3
    HDA NVidia, HDMI 0
    Direct hardware device without any conversions
hw:CARD=NVidia,DEV=7
    HDA NVidia, HDMI 1
    Direct hardware device without any conversions
hw:CARD=NVidia,DEV=8
    HDA NVidia, HDMI 2
    Direct hardware device without any conversions
hw:CARD=NVidia,DEV=9
    HDA NVidia, HDMI 3
    Direct hardware device without any conversions
hw:CARD=NVidia,DEV=10
    HDA NVidia, HDMI 4
    Direct hardware device without any conversions
plughw:CARD=NVidia,DEV=3
    HDA NVidia, HDMI 0
    Hardware device with all software conversions
plughw:CARD=NVidia,DEV=7
    HDA NVidia, HDMI 1
    Hardware device with all software conversions
plughw:CARD=NVidia,DEV=8
    HDA NVidia, HDMI 2
    Hardware device with all software conversions
plughw:CARD=NVidia,DEV=9
    HDA NVidia, HDMI 3
    Hardware device with all software conversions
plughw:CARD=NVidia,DEV=10
    HDA NVidia, HDMI 4
    Hardware device with all software conversions
usbstream:CARD=NVidia
    HDA NVidia
    USB Stream Output

[MrEen]

Hi Philipp,

You've already tried the things I would have had you try so we might have some difficulty making any progress here.

First, let's see this output to see if there are any errors that might help point us in the right direction:

Code: Select all

dmesg | grep -C1 -E 'ALSA|HDA|sof|HDMI|snd[_-]|sound|hda.codec|hda.intel'

If that returns nothing, throw a sudo in front of it. For some reason, kernels 5.7 and higher now require sudo for dmesg output.

[Philipp91]

Thanks for your help. Here's the log output:

Code: Select all

[    0.148805] ACPI: Added _OSI(Linux-Dell-Video)
[    0.148805] ACPI: Added _OSI(Linux-Lenovo-NV-HDMI-Audio)
[    0.148805] ACPI: Added _OSI(Linux-HPI-Hybrid-Graphics)
--
[    0.519186] Freeing initrd memory: 84804K
[    0.539545] PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
[    0.539549] software IO TLB: mapped [mem 0x7e9f6000-0x829f6000] (64MB)
[    0.539750] check: Scanning for low memory corruption every 60 seconds
--
[    0.666799] integrity: Loading X.509 certificate: UEFI:db
[    0.666830] integrity: Loaded X.509 cert 'Microsoft Corporation UEFI CA 2011: 13adbf4309bd82709c8cd54f316ed522988a1bd4'
[    0.666831] integrity: Loading X.509 certificate: UEFI:db
[    0.666851] integrity: Loaded X.509 cert 'Microsoft Windows Production PCA 2011: a92902398e16c49778cd90f99e4f9ae17c55af53'
[    0.667141] integrity: Loading X.509 certificate: UEFI:MokListRT
--
[    4.728299] input: HP WMI hotkeys as /devices/virtual/input/input22
[    4.831215] snd_hda_intel 0000:00:1f.3: enabling device (0100 -> 0102)
[    4.833615] snd_hda_intel 0000:01:00.1: Disabling MSI
[    4.833618] snd_hda_intel 0000:01:00.1: Handle vga_switcheroo audio client
[    4.873723] snd_hda_codec_realtek hdaudioC0D0: autoconfig for ALC891: line_outs=1 (0x21/0x0/0x0/0x0/0x0) type:line
[    4.873725] snd_hda_codec_realtek hdaudioC0D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    4.873726] snd_hda_codec_realtek hdaudioC0D0:    hp_outs=1 (0x17/0x0/0x0/0x0/0x0)
[    4.873727] snd_hda_codec_realtek hdaudioC0D0:    mono: mono_out=0x0
[    4.873727] snd_hda_codec_realtek hdaudioC0D0:    inputs:
[    4.873728] snd_hda_codec_realtek hdaudioC0D0:      Mic=0x18
[    4.873729] snd_hda_codec_realtek hdaudioC0D0:      Line=0x1b
[    4.884936] input: HDA Intel PCH Mic as /devices/pci0000:00/0000:00:1f.3/sound/card0/input23
[    4.884984] input: HDA Intel PCH Line as /devices/pci0000:00/0000:00:1f.3/sound/card0/input24
[    4.885034] input: HDA Intel PCH Line Out as /devices/pci0000:00/0000:00:1f.3/sound/card0/input25
[    4.885069] input: HDA Intel PCH Front Headphone as /devices/pci0000:00/0000:00:1f.3/sound/card0/input26
[    4.906173] intel_rapl_common: Found RAPL domain package
--
[    5.592199] r8169 0000:03:00.0 enp3s0: Link is Down
[    5.948947] input: HDA NVidia HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input27
[    5.949003] input: HDA NVidia HDMI/DP,pcm=7 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input28
[    5.949049] input: HDA NVidia HDMI/DP,pcm=8 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input29
[    5.949098] input: HDA NVidia HDMI/DP,pcm=9 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input30
[    5.949139] input: HDA NVidia HDMI/DP,pcm=10 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input31
[    8.062940] r8169 0000:03:00.0 enp3s0: Link is Up - 1Gbps/Full - flow control rx/tx
--
[ 3154.341424] sd 0:0:0:0: [sda] Starting disk
[ 3154.520018] snd_hda_codec_hdmi hdaudioC1D0: HDMI: invalid ELD data byte 45
[ 3154.684246] usb 1-4: reset high-speed USB device number 2 using xhci_hcd
--
[ 3155.991968] PM: hibernation exit
[ 3156.063923] snd_hda_codec_hdmi hdaudioC1D0: HDMI: invalid ELD data byte 9
[ 3156.121925] audit: type=1400 audit(1618332688.740:25): apparmor="DENIED" operation="capable" profile="/usr/sbin/cups-browsed" pid=6142 comm="cups-browsed" capability=23  capname="sys_nice"

(No new entries are added while watching a video or so.)

[MrEen]

Interesting error:

Code: Select all

[ 3154.520018] snd_hda_codec_hdmi hdaudioC1D0: HDMI: invalid ELD data byte 45

I say interesting because C1D0 doesn't exist. The device numbers on card 1 are 3, 7, 8, 9 and 10.

The error sprang up about 53 minutes after you booted up. Is it possible it had been that long before you played sound that experienced the popping/crackling?

[Philipp91]

Hard to say retrospectively, but I reproduced from the beginning. I booted freshly (no hibernate/resume) and got this:

Code: Select all

dmesg | grep -C1 -E 'ALSA|HDA|sof|HDMI|snd[_-]|sound|hda.codec|hda.intel'
[    0.149029] ACPI: Added _OSI(Linux-Dell-Video)
[    0.149029] ACPI: Added _OSI(Linux-Lenovo-NV-HDMI-Audio)
[    0.149029] ACPI: Added _OSI(Linux-HPI-Hybrid-Graphics)
--
[    0.515297] Freeing initrd memory: 84804K
[    0.539769] PCI-DMA: Using software bounce buffering for IO (SWIOTLB)
[    0.539773] software IO TLB: mapped [mem 0x7e9f6000-0x829f6000] (64MB)
[    0.539966] check: Scanning for low memory corruption every 60 seconds
--
[    0.668976] integrity: Loading X.509 certificate: UEFI:db
[    0.668995] integrity: Loaded X.509 cert 'Microsoft Corporation UEFI CA 2011: 13adbf4309bd82709c8cd54f316ed522988a1bd4'
[    0.668995] integrity: Loading X.509 certificate: UEFI:db
[    0.669010] integrity: Loaded X.509 cert 'Microsoft Windows Production PCA 2011: a92902398e16c49778cd90f99e4f9ae17c55af53'
[    0.669443] integrity: Loading X.509 certificate: UEFI:MokListRT
--
[    4.896369] RAPL PMU: hw unit of domain dram 2^-14 Joules
[    5.016414] snd_hda_intel 0000:00:1f.3: enabling device (0100 -> 0102)
[    5.016757] snd_hda_intel 0000:01:00.1: Disabling MSI
[    5.016760] snd_hda_intel 0000:01:00.1: Handle vga_switcheroo audio client
[    5.051125] snd_hda_codec_realtek hdaudioC0D0: autoconfig for ALC891: line_outs=1 (0x21/0x0/0x0/0x0/0x0) type:line
[    5.051127] snd_hda_codec_realtek hdaudioC0D0:    speaker_outs=0 (0x0/0x0/0x0/0x0/0x0)
[    5.051128] snd_hda_codec_realtek hdaudioC0D0:    hp_outs=1 (0x17/0x0/0x0/0x0/0x0)
[    5.051129] snd_hda_codec_realtek hdaudioC0D0:    mono: mono_out=0x0
[    5.051130] snd_hda_codec_realtek hdaudioC0D0:    inputs:
[    5.051131] snd_hda_codec_realtek hdaudioC0D0:      Mic=0x18
[    5.051132] snd_hda_codec_realtek hdaudioC0D0:      Line=0x1b
[    5.064469] input: HDA Intel PCH Mic as /devices/pci0000:00/0000:00:1f.3/sound/card0/input23
[    5.064503] input: HDA Intel PCH Line as /devices/pci0000:00/0000:00:1f.3/sound/card0/input24
[    5.064533] input: HDA Intel PCH Line Out as /devices/pci0000:00/0000:00:1f.3/sound/card0/input25
[    5.064561] input: HDA Intel PCH Front Headphone as /devices/pci0000:00/0000:00:1f.3/sound/card0/input26
[    5.106191] intel_rapl_common: Found RAPL domain package
--
[    5.824427] r8169 0000:03:00.0 enp3s0: Link is Down
[    6.162128] input: HDA NVidia HDMI/DP,pcm=3 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input27
[    6.162173] input: HDA NVidia HDMI/DP,pcm=7 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input28
[    6.162206] input: HDA NVidia HDMI/DP,pcm=8 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input29
[    6.162238] input: HDA NVidia HDMI/DP,pcm=9 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input30
[    6.162271] input: HDA NVidia HDMI/DP,pcm=10 as /devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1/input31
[    8.297660] r8169 0000:03:00.0 enp3s0: Link is Up - 1Gbps/Full - flow control rx/tx
...
[   18.965092] logitech-hidpp-device 0003:046D:4082.0006: HID++ 4.5 device connected.
the end

Then I opened Chrome, watched the test video and heard the usual crackles. No dmesg output was added at all.

[Philipp91]

I recorded a portion of a YT video that has many crackling noises, with Audacity and pavucontrol to make it record from the "monitor" of the HDMI output device. In the audio wave displayed by Audacity nothing looks like a crack. The places where it cracks are entirely flat/zero. When I play back the recording, I hear cracks in some cases:

• I never hear any cracks during playback when I'm playing simultaneously something else (and something "gap-less", e.g. a radio stream).
• Play right in Audacity -> cracks
• Play in Audacity without PulseAudio (but instead straight to ALSA): Couldn't get this to work because my HDMI device number 7 doesn't show up there and the others don't work.
• Export ogg and play in Rhythmbox or Celluloid -> cracks
• Export wav and play in Rhythmbox or Celluloid -> no cracks (!)
• Without pulseaudio but instead: APULSE_PLAYBACK_DEVICE=hw:NVidia,7 apulse ffplay MyFile.ogg -> cracks
• Without pulseaudio but instead: APULSE_PLAYBACK_DEVICE=hw:NVidia,7 apulse aplay MyFile.wav -> no cracks, though the audio is a little messed up in different ways towards the end.

So with wav there are no cracks. Perhaps that's because wav is actively "playing something" (albeit zeros) all the time, including when there was no audio recorded, whereas codecs like ogg do not send anything to the output device at such times?

Also now that I can play back the exact same snippet over and over again, I noticed that the cracks aren't always in the same place. So they're not caused by something *in* the audio, but perhaps by the absence of audio over a given time and the system's reaction to it. Something like a "quick sleep" for less than a second or so.

[Philipp91]

I've the small part of the recording where there's no talking at all (a human listener would say "there is nothing in this recording") into a new Audacity project and repeated it a bunch of times so that it becomes 10 seconds long. If you want to play with it, you can download it (for 30 days) here: https://easyupload.io/dphlvq

Now I've made the following experiments/observations:

• Playing this in Audacity -> cracks
• In the "Audio Track" menu under "Format, converting from 32 float to 24-Bit PCM -> still cracks.
• Converting to 16-Bit PCM -> does not crack anymore
• Converting back to 24-Bit PCM of 32 float -> does not crack anymore

So something in the 16-Bit PCM encoding makes the (thing that causes the) cracks go away permanently. Visually (e.g. in the spectogram), there's no difference, but in the file system, all the many .au files in the eff directory have been replaced with a .wav file. And as I had found yesterday already, those don't crackle.

[Philipp91]

Here's a couple more experiments with strange results:

• Export the crackling track in Audacity as FLAC, MP3 or WMA -> does not crack in Rhythmbox.
• Reimport MP3 or WMA -> still does not crack (so MP3/WMA destroyed whatever causes the crackles)
• Reimport FLAC -> cracks again (so FLAC didn't permanently destroy it, yet when played externally it somehow doesn't occur)

All reimported Audacity projects store 4 .au files with a total of 2.5MB in the ./eff/d1f directory on disk, so it doesn't seem to be caused by whether the on-disk format is au vs wav either. Here are the reimported projects: https://easyupload.io/nsrv7j I can't really tell the difference between what they contain, but one of them has crackles and the other does not.

[Philipp91]

And here's another observation: There are no crackles with HDMI, only with DisplayPort (otherwise the same hardware, driver, ...). When I connect both cables in parallel, I can switch between the two outputs while the video is playing, and clearly only DisplayPort audio has crackles.
(But DisplayPort+Windows or DisplayPort+wav works fine still.)

(This hints at a simple workaround -- just using HDMI. But that's not as easy in practice because I have two computers, my monitor only has one HDMI input, and the other computer doesn't have a DisplayPort output, so this would mean I have to crawl under my desk at least twice per day to replug the cables.)

I diffed various status outputs. aplay -l and aplay -L remain the same. But pactl list cards has the following line different:
With DisplayPort (broken) it says: Active Profile: output:hdmi-stereo-extra1
With HDMI (working) it says: Active Profile: output:hdmi-stereo

[Philipp91]

What would be the right place to report this issue? One of the ALSA GitHub repositories or their mailing list? Or a kernel driver bug?

Even though I have somewhat of a workaround, I agree with Ubuntu's philosophy: "We want audio to be working out of the box, without users having to apply fixes manually."

[Philipp91]

I can now reproduce the same issue with an entirely different computer (laptop instead of desktop PC, no Nvidia graphics card, ...) but with the same monitor. Also here, it works fine over HDMI but crackles over DisplayPort.