Audio debugging techniques - Ubuntuodm.ubuntu.com/uhs/2011/Audio Debugging Techniques.pdfAudio...
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Audio debugging techniques December 8th 2011 David Henningsson Audio Hardware Enablement Engineer
Transcript of Audio debugging techniques - Ubuntuodm.ubuntu.com/uhs/2011/Audio Debugging Techniques.pdfAudio...
Audio debugging techniquesDecember 8th 2011
David Henningsson
Audio Hardware Enablement Engineer
2 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Contents
● Audio stack overview
● Mixer problems
● Streaming problems
● Jack sensing
● Handing over
● What's happening upstream?
3 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Audio stack overview
HDA codec driver
HDA controller driver
HDA controller(southbridge)
HDA codecchip
ALSA kernel core
ALSA library
PulseAudio
VOIP(Skype)
GStreamerlibrary
Media player
User space Kernel space
HDA bus
Hardware
4 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Audio stack overview – the codec
● Use the “codecgraph” utility to make graphs such as the above
5 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Pin Configuration Default
● Is filled in by firmware (BIOS/UEFI) at boot
● Tells which codec pins are connected to what
● For new computers we rely on this field heavily
● Problems in released hardware? We create a “driver quirk”.
● Problems in pre-release hardware? We feed this information back to firmware developers for correction.
● Hda-jack-retask demo!
6 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Mixer problems
● Typical symptoms:
● One output or input works but not the other, e g external mic works but not internal mic
● Changing volume/gain has no effect, or only has effect for parts of the slider
● Initial check:
● Have you plugged the mic/headphones in? :-)
● Check mute, volume and connector in PulseAudio
● Check mutes and volumes in alsamixer
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Mixer control names
● The HDA Codec driver creates mixer controls
● PulseAudio abstracts several mixer controls to one master control
● For PulseAudio to know, these mixer controls must have specific names
● Information at the codec level:
● /proc/asound/<card name>/codec#<address> will tell the mapping between HDA nodes and mixer controls
● Information at userspace level:
● /usr/share/pulseaudio/alsa-mixer/paths/* will tell how the different mixer controls are used in different scenarios
8 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
PCM / Streaming problems
● Typical symptom:
● Audio breaks up, glitches or crackles
● These are typically non-trivial to resolve
● A PulseAudio verbose log can help with initial analysis
● Possible causes:
● Broken application (does not submit data to PulseAudio in time)
● Problem with position reports from the hardware
● Other bugs in PulseAudio or HDA controller driver
9 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Jack sensing
● What happens when you plug something in?
● For headphones: Auto-mute of speakers is done in the kernel
● For microphones: Auto-switch of mic sometimes done in the kernel
● Notification is sent to userspace
● PulseAudio picks notification up
● Information is used to select correct port for volume control
● Userspace notification/handling
● ...is new in Ubuntu 11.10
● ...will be improved in Ubuntu 12.04
● Hda-jack-sense-test demo!
10 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
HDMI/DisplayPort audio
● Nvidia usually has four output pins, Intel often has three
● Problem: which one is the right one?
● Best if firmware sets the Pin Configuration Default
● If not, we have to rely on jack sensing (work in progress)
● Note: Nvidia and ATI/AMD both require proprietary drivers for HDMI audio to work
11 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Handing over - ALSA
● Is the bug resolved upstream?
● https://wiki.ubuntu.com/Audio/UpgradingAlsa/DKMS
● Reporting a bug in Ubuntu:
● ubuntu-bug audio
● Making an alsa-info report:
● https://wiki.ubuntu.com/Audio/AlsaInfo
● Note: If you're dealing with pre-release hardware, be cautious not to submit confidential information!
● Primary upstream contact: [email protected] public mailing list
● Avoid ALSA's bug tracker
● Canonical can help out with upstream contacts
12 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Handing over - PulseAudio
● Reporting a bug in Ubuntu:
● ubuntu-bug audio
● Making an PulseAudio verbose log:
● https://wiki.ubuntu.com/PulseAudio/Log
● Note: If you're dealing with pre-release hardware, be cautious not to submit confidential information!
● Primary upstream contact: [email protected] public mailing list
● Canonical can help out with upstream contacts
13 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
What's happening upstream - ALSA
● A slowly progressing, but ongoing effort, to consolidate the codec parsers
● Machine quirks are inserted and removed regularly
● A new interface for jack sensing
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What's happening upstream - PulseAudio
● Passthrough support
● Jask sensing
● UCM
● Routing infrastructure
15 Canonical Confidential Ubuntu Hardware Summit. December 8th 2011
Update and Links
● You can download presentation and notes from my blog:
http://voices.canonical.com/david.henningsson/
Thank you
Questions ?
