Noise crackling/Popping when PCM muted

[davie]

When PCM is muted and audio is playing, then instead of hearing no sound I hear a crackling/popping noise. Audio is fine when PCM is at anything other than zero. I'm using ubuntu 8.10, 0.9.10, and a built in intel sound card on a dell d620 laptop.

There are quite a few reports in the ubuntu bugtracker about this issue, see for example:

• https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/220842
• https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/272321

lspci -vvnn gives lspci gives:

00:1b.0 Audio device [0403]: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller [8086:27d8] (rev 01)
	Subsystem: Dell Device [1028:01c2]
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 21
	Region 0: Memory at efffc000 (64-bit, non-prefetchable) [size=16K]
	Capabilities: [50] Power Management version 2
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=55mA PME(D0+,D1-,D2-,D3hot+,D3cold+)
		Status: D0 PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [60] Message Signalled Interrupts: Mask- 64bit+ Queue=0/0 Enable-
		Address: 0000000000000000  Data: 0000
	Capabilities: [70] Express (v1) Root Complex Integrated Endpoint, MSI 00
		DevCap:	MaxPayload 128 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
			ExtTag- RBE- FLReset-
		DevCtl:	Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
			RlxdOrd- ExtTag- PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 128 bytes, MaxReadReq 128 bytes
		DevSta:	CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr+ TransPend-
		LnkCap:	Port #0, Speed unknown, Width x0, ASPM unknown, Latency L0 <64ns, L1 <1us
			ClockPM- Suprise- LLActRep- BwNot-
		LnkCtl:	ASPM Disabled; Disabled- Retrain- CommClk-
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed unknown, Width x0, TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
	Capabilities: [100] Virtual Channel <?>
	Capabilities: [130] Root Complex Link <?>
	Kernel driver in use: HDA Intel
	Kernel modules: snd-hda-intel

Let me know if there's anything else i can do to help debug this.

[davie]

i forgot to mention, if i mute master, rather than PCM, then I don't get the problem.

[coling]

I presume you are muting the PCM and Master of the alsa device itself? Pulse only has a master to mute, but I wanted to ensure you are comparing apples to apples! (e.g. comparing the master on the pulse mixer vs. PCM on the alsa mixer is probably not a fair comparison).

If you play some audio via alsa directly does this phenominom still happen? e.g. mplayer -ao alsa:device=hw,0 blah.ogg If it still occurs, it's definitely an alsa bug (which is what I suspect in any case!)

[davie]

I'm muting using gnome-volume control - I'm not sure which that controls, so let me know if I should be doing something else.

Playing using mplayer -ao alsa:device=hw,0 mymp3.mp3 (after killing pulseaudio) does not have a problem - when muted there is no sound. Playing using mplayer -ao pulse,0 mymp3.mp3 does show the problem when muted - crackling/hissing noise.

Thanks

[lennart]

This is not a PA problem. Please report to ALSA upstream.