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Sound Software: Difference between revisions
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Sound on Linux is the absolute biggest bunch of bullshit ever, closely | Sound on Linux is the absolute biggest bunch of bullshit ever, closely trailed by sound on computers and sound itself. | ||
[[File:Pcm1792a.jpeg|thumb|right|Burr Brown PCM 1792A block diagram]] | |||
==Terminology== | ==Terminology== | ||
[[File:Burrbrown1792a.jpeg|right|thumb|Burr Brown PCM 1792A DAC]] | |||
* HDA: Intel High Definition Audio specification | * HDA: Intel High Definition Audio specification | ||
* ELD: [[EDID]]-Like Data. Structured capability data returned by graphics-oriented devices. | * ELD: [[EDID]]-Like Data. Structured capability data returned by graphics-oriented devices. | ||
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* DAT: Digital Audio Tape, a 48k/44.1k/32k medium using 4mm magnetic tape | * DAT: Digital Audio Tape, a 48k/44.1k/32k medium using 4mm magnetic tape | ||
==Hardware== | |||
I recommend the [http://www.guru3d.com/article/asus-xonar-essence-st-deluxe-review/ Xonar Essence ST] PCI card, making use of the [[#File:Pcm1792a.pdf|Burr Brown PCM 1792A]] DAC and Cirrus CS5381 ADC, for an in-machine solution. | |||
* You'll need the <tt>snd-virtuoso</tt> ALSA driver (C-Media CMI8788 Oxygen HD Audio). | |||
===USB DACs=== | |||
* Watch for true USB Audio Class 2.0 and solid asynchronous solutions | |||
* "[http://www.eetimes.com/design/audio-design/4009467/The-D-A-diaries-A-personal-memoir-of-engineering-heartache-and-triumph The D-A Diaries]" is an excellent article regarding the difficulties of producing accurate sound via USB output. | |||
** Essentially: USB has a clockless wire, thus there must be clocks on each side, which *will* drift | |||
** If the USB device doesn't have its own crystal, it might even time based off AC power | |||
* USB Audio Class 1 is limited to the 24bit, 96KHz maximum supported by USB 1.x (12Mbps) | |||
== Kernel == | == Kernel == | ||
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* The (somewhat outdated) [http://lau.linuxaudio.org/audio_quality_howto.htm Linux High-Quality Audio HOWTO] | * The (somewhat outdated) [http://lau.linuxaudio.org/audio_quality_howto.htm Linux High-Quality Audio HOWTO] | ||
* The computeraudiophile.com [http://www.computeraudiophile.com/faq Computer Audiophile FAQs] | * The computeraudiophile.com [http://www.computeraudiophile.com/faq Computer Audiophile FAQs] | ||
* "[http://www.head-fi.org/t/160612/pros-cons-of-usb-dac-against-sound-card Pros and Cons of USB DACs]" on head-fi.org | |||
* "[http://www.mythtv.org/wiki/Configuring_Digital_Sound Configuring Digital Sound]" on the MythTV wiki | * "[http://www.mythtv.org/wiki/Configuring_Digital_Sound Configuring Digital Sound]" on the MythTV wiki | ||
* [http://www.thewelltemperedcomputer.com/index.html The Well-Tempered Computer] and the [http://www.digitalaudioblog.com Digital Audio Blog] | * [http://www.thewelltemperedcomputer.com/index.html The Well-Tempered Computer] and the [http://www.digitalaudioblog.com Digital Audio Blog] | ||
* ...and, of course, [http://www.stereophile.com/ stereophile.com] | * ...and, of course, [http://www.stereophile.com/ stereophile.com] |
Latest revision as of 01:42, 30 December 2011
Sound on Linux is the absolute biggest bunch of bullshit ever, closely trailed by sound on computers and sound itself.
![](/dankwiki/images/thumb/4/45/Pcm1792a.jpeg/300px-Pcm1792a.jpeg)
Terminology
![](/dankwiki/images/thumb/4/45/Burrbrown1792a.jpeg/300px-Burrbrown1792a.jpeg)
- HDA: Intel High Definition Audio specification
- ELD: EDID-Like Data. Structured capability data returned by graphics-oriented devices.
- ELD can also mean Enhanced Low Delay (in for instance AAC-ELD)
- PD/ELDV: Presence Detect/ELD-Valid bits aka "Unsolicited Responses".
- PD indicates a change in presence or the ELDV bit
- ELDV indicates new ELD information
- EAX: Environmental audio eXtensions
- S/PDIF: Sony/Phillips Digital Interconnect Format (IEC 60958 type II / IEC 958)
- 10m max cable distance
- TOSLINK F05 / EIAJ-Optical and coax RCA connections
- Carries DTS and Dolby Digital compressed audio for >2 PCM (IEC 61937)
- AES3: commercial-grade
- 3-pin XLR (balanced) and BNC (unbalanced) connections
- CDDA: CD Digital Audio, 2-channel 44.1k PCM
- DAT: Digital Audio Tape, a 48k/44.1k/32k medium using 4mm magnetic tape
Hardware
I recommend the Xonar Essence ST PCI card, making use of the Burr Brown PCM 1792A DAC and Cirrus CS5381 ADC, for an in-machine solution.
- You'll need the snd-virtuoso ALSA driver (C-Media CMI8788 Oxygen HD Audio).
USB DACs
- Watch for true USB Audio Class 2.0 and solid asynchronous solutions
- "The D-A Diaries" is an excellent article regarding the difficulties of producing accurate sound via USB output.
- Essentially: USB has a clockless wire, thus there must be clocks on each side, which *will* drift
- If the USB device doesn't have its own crystal, it might even time based off AC power
- USB Audio Class 1 is limited to the 24bit, 96KHz maximum supported by USB 1.x (12Mbps)
Kernel
- Determine: are there still ALSA hardware drivers inferior to their OSS equivalents? Assuming no...
- OSS emulation: kernel, library, or neither?
- Kernel: snd_pcm_oss, snd_mixer_oss, snd_seq_oss provide /dev/dsp, /dev/seq, /dev/mixer
- Library: aoss sets LD_PRELOAD to include libaoss.so
- Neither: force fail on attempts to use OSS
- Might be better if OSS-only code is old and crappy, as suggested by OSS-only nature, as it'll eliminate such code. Might also be better if OSS compatability introduces any kinds of issues. Might be worse if OSS code is better-written than ALSA code alternatives, and OSS compatability introduces no problems.
/proc/asound
- /proc/asound/cards: Maps physical devices to ALSA card numbers
[eschatomatic](0) $ cat /proc/asound/cards 0 [Intel ]: HDA-Intel - HDA Intel HDA Intel at 0xe8260000 irq 43 1 [NVidia ]: HDA-Intel - HDA NVidia HDA NVidia at 0xe3080000 irq 17 [eschatomatic](0) $
- /proc/asound/cardX: Device details indexed by ALSA card number, including codec and ELD dumps
- NOTE: X being loaded is typically required for ELD detection!
- /proc/asound/devices: Maps functional devices to ALSA card:dev number pairs and describes function
- /proc/asound/modules: Maps kernel modules to ALSA card numbers
- /proc/asound/pcm: Maps card:dev numbers to allocated PCM streams
ALSA configuration
- What ought go in /etc/asoundrc? It's a complete enigma.
- FIXME
HDMI
- FIXME
Sound Servers
- pulseaudio -- crashes mpd every time I try to use it (no longer true as of Fall 2008)
- To drive ALSA through pulseaudio by default:
pcm.!default { type pulse } ctl.!default { type pulse }
- jack -- low-latency, professional software; it frightens me
- esd -- deprecated, replaced by pulseaudio's esd-compat module
Hardware
- PulseAudio can supposedly use a plugin together with HAL to drive dynamic devices
See Also
- A Guide to Linux Sound APIs by Lennart Poettering of PulseAudio
- Linux Audio: It's a Mess from LWN
- PulseAudio -- The Perfect Setup
- Ubuntu has a HOWTO on ... fixing pulseaudio. Yikes.
- mpd, the music player daemon
- The Intel High Definition Audio specification
- The ALSA Wiki
- The (somewhat outdated) Linux High-Quality Audio HOWTO
- The computeraudiophile.com Computer Audiophile FAQs
- "Pros and Cons of USB DACs" on head-fi.org
- "Configuring Digital Sound" on the MythTV wiki
- The Well-Tempered Computer and the Digital Audio Blog
- ...and, of course, stereophile.com