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I have a Home Theater Personal Computer. It is connected via HDMI to a Samsung HDTV and then by optical cable to a 5.1 receiver.

Mythtv plays very well, the problem is other computer sounds. These seem to overdrive the the speakers - causing loud spitting unless the volume is very low..

  • For instance, when playing audio using Firefox and mog.com when the ALSA plug-in [npviewer.bin] is set low enough to stop the spitting from overdriving in Sound Preferences/Application, the volume is too low to be useful and the volume level of the right speaker is much louder than other speakers. The same thing happens when playing an audio CD and with system sounds.

The Alsa mixer shows only four check boxes for playback and , IEC958, IEC958 1, IEC958 2, and IEC958 3; with the first two checked. Only IEC958 1 affects the audio. For capture, it reports the device does not have any capture devices.

The specs are:

  • Ubuntu 10.10 (fully updated)
  • Linux 2.6.35-31-generic (x86_64)
  • Athlon(tm) X3 445 Processor (3x3.1GHz)
  • 4055MB
  • Audio Adapter:HDA-Intel-HDA NVidia[nVidia Corporation High Definition Audio Controller/ (rev a1)]
  • GeForce GT 240/PCI/SSE2

Mythtv fixes/0.24 (v0.24.1-112-g40f3bae)

The motherboard has built in sound that is disabled in the BIOS.

alsa-info here.

The Loaded snd modules:

snd_hda_codec ⋯ HDA codec core
snd_hda_codec_nvhdmi ⋯ NVIDIA HDMI HD-audio codec
snd_hda_intel ⋯ Intel HDA driver
snd_hwdep ⋯ Hardware dependent layer
snd_page_alloc ⋯ Memory allocator for ALSA system.
snd_pcm ⋯ Midlevel PCM code for ALSA.
snd_rawmidi ⋯ Midlevel RawMidi code for ALSA.
snd_seq ⋯ Advanced Linux Sound Architecture sequencer.
snd_seq_device ⋯ ALSA sequencer device management
snd_seq_midi ⋯ Advanced Linux Sound Architecture sequencer MIDI synth.
snd_seq_midi_event ⋯ MIDI byte <-> sequencer event coder
snd_timer ⋯ ALSA timer interface

From lspci -vvnn for nvidia

01:00.0 VGA compatible controller [0300]: nVidia Corporation GT215 [GeForce GT 240] [10de:0ca3] (rev a2) (prog-if 00 [VGA controller])
    Subsystem: eVga.com. Corp. Device [3842:1242]
    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
    Interrupt: pin A routed to IRQ 18
    Region 0: Memory at fc000000 (32-bit, non-prefetchable) [size=16M]
    Region 1: Memory at d0000000 (64-bit, prefetchable) [size=256M]
    Region 3: Memory at ce000000 (64-bit, prefetchable) [size=32M]
    Region 5: I/O ports at d800 [size=128]
    [virtual] Expansion ROM at fde80000 [disabled] [size=512K]
    Capabilities: [60] Power Management version 3
        Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
        Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
    Capabilities: [68] MSI: Enable- Count=1/1 Maskable- 64bit+
        Address: 0000000000000000  Data: 0000
    Capabilities: [78] Express (v2) Endpoint, MSI 00
        DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s unlimited, L1 <64us
            ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
        DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
            RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
            MaxPayload 128 bytes, MaxReadReq 512 bytes
        DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
        LnkCap: Port #0, Speed 2.5GT/s, Width x16, ASPM L0s L1, Latency L0 <512ns, L1 <4us
            ClockPM+ Surprise- LLActRep- BwNot-
        LnkCtl: ASPM Disabled; RCB 128 bytes Disabled- Retrain- CommClk+
            ExtSynch- ClockPM+ AutWidDis- BWInt- AutBWInt-
        LnkSta: Speed 2.5GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
        DevCap2: Completion Timeout: Not Supported, TimeoutDis+
        DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-
        LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-, Selectable De-emphasis: -6dB
             Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
             Compliance De-emphasis: -6dB
        LnkSta2: Current De-emphasis Level: -6dB
    Capabilities: [b4] Vendor Specific Information: Len=14 <?>
    Capabilities: [100 v1] Virtual Channel
        Caps:   LPEVC=0 RefClk=100ns PATEntryBits=1
        Arb:    Fixed- WRR32- WRR64- WRR128-
        Ctrl:   ArbSelect=Fixed
        Status: InProgress-
        VC0:    Caps:   PATOffset=00 MaxTimeSlots=1 RejSnoopTrans-
            Arb:    Fixed- WRR32- WRR64- WRR128- TWRR128- WRR256-
            Ctrl:   Enable+ ID=0 ArbSelect=Fixed TC/VC=ff
            Status: NegoPending- InProgress-
    Capabilities: [128 v1] Power Budgeting <?>
    Capabilities: [600 v1] Vendor Specific Information: ID=0001 Rev=1 Len=024 <?>
    Kernel driver in use: nvidia
    Kernel modules: nvidia-current, nouveau, nvidiafb

01:00.1 Audio device [0403]: nVidia Corporation High Definition Audio Controller [10de:0be4] (rev a1)
    Subsystem: eVga.com. Corp. Device [3842:1242]
    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 B routed to IRQ 19
    Region 0: Memory at fde7c000 (32-bit, non-prefetchable) [size=16K]
    Capabilities: [60] Power Management version 3
        Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
        Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
    Capabilities: [68] MSI: Enable- Count=1/1 Maskable- 64bit+
        Address: 0000000000000000  Data: 0000
    Capabilities: [78] Express (v2) Endpoint, MSI 00
        DevCap: MaxPayload 128 bytes, PhantFunc 0, Latency L0s <4us, L1 <64us
            ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
        DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
            RlxdOrd- ExtTag+ PhantFunc- AuxPwr- NoSnoop+
            MaxPayload 128 bytes, MaxReadReq 512 bytes
        DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
        LnkCap: Port #0, Speed 2.5GT/s, Width x16, ASPM L0s L1, Latency L0 <512ns, L1 <1us
            ClockPM+ Surprise- LLActRep- BwNot-
        LnkCtl: ASPM L0s L1 Enabled; RCB 128 bytes Disabled- Retrain- CommClk+
            ExtSynch- ClockPM+ AutWidDis- BWInt- AutBWInt-
        LnkSta: Speed 2.5GT/s, Width x16, TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
        DevCap2: Completion Timeout: Not Supported, TimeoutDis+
        DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-
        LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-, Selectable De-emphasis: -6dB
             Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
             Compliance De-emphasis: -6dB
        LnkSta2: Current De-emphasis Level: -6dB
    Kernel driver in use: HDA Intel
    Kernel modules: snd-hda-intel
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2 Answers 2

up vote 0 down vote accepted

Out of hope, the last refuge of the desperate, I used Synaptic to re-install everything I could find for ALSA and Pulse Audio.

This fixed the problem.

Remember about hope, which is generally unreliable.

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I think pulse audio is disabled on mythbuntu by default. Anyways you would need to ensure it is 48khz. Got to audio settings and enable advanced option. Select the force audio to 48khz option or it is something similar. This worked for me without reinstalling anything. It is digital out after all.

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1  
Occasionally the audio stops for all but mythtv, but switching to mythtv and playing something with audio, then switching back seems to fix that. I'm suspecting npviewer. –  keepitsimpleengineer Jan 27 '12 at 18:40

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