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Old 19th March 2013, 05:00 PM   #2101
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Default zita-lrx jack module

Hello all,

Just to share an information, zita-lrx jack module has been integrated in the Ubuntu quantal distribution :

zita-lrx :A command line jack application providing 2, 3, or 4-band, 4th order crossover filters

Ubuntu ? Détails du paquet zita-lrx dans quantal

Linux + Jack + Jamin + zita-lrx + m-audio 1010LT = 30 band graphic EQ + 4 parametrics EQ + 4 way crossover

I'm waiting for a second hand 1010LT, should be at home next week

Zita-lrx - First release 05/01/2012
------------------------------------

Zita-lrx is a command line jack application providing 2, 3, or 4-band,
4th order crossover filters. The filter type is continuously variable
between Linkwitz-Riley (-6dB at the xover frequency) and Butterworth
(-3 dB at the xover frequency). Outputs are exactly phase matched in
the crossover regions.

The application supports up to 16 channels. This is a compile time
limit and easily changed, but if you have many channels it may be
a better idea to use two or more instances in order to spread the
load in an SMP system. Not that it would matter much - on my old
2 GHz P4, CPU load is around 0.6% per channel for four bands.

Configuration is by a text file using 'OSC' style syntax (similar
to Ambdec and Jconvolver). Apart from the basic filter parameters,
the following can be set:

- Channel labels (used for naming Jack ports).
- Frequency band names (used in output port names).
- Optional output autoconnections.
- For each channel: gain and delay (in ms).
- For each frequency band: gain and delay.

Last edited by Pascal GUERIN; 19th March 2013 at 05:08 PM.
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Old 6th April 2013, 11:40 AM   #2102
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Just received my 1010LT card last week and i've done few tests, results seems promissing. I'm using zita-lrx to cross my sub at 90hz in a 2.1 configuration. Just to get an idea of the product see below the jack connection from example1.zlr file configuration wich is part of the module.

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Old 14th April 2013, 08:40 PM   #2103
rdf is offline rdf  Canada
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Default Openelec Frodo

The most recent release of this live Linux XBMC distribution has a new audio engine which is said to automatically stream bit perfect data to the DAC. It finds a Micromega MyDAC on USB easily enough and 'cat /proc/asound/MYDAC/stream0' confirms the sample rates are switching properly all the way to 192 kHz:

openelec:~ # cat /proc/asound/MYDAC/stream0
MICROMEGA MICROMEGA MYDAC at usb-0000:00:06.1-3, high speed : USB Audio

Playback:
Status: Running
Interface = 1
Altset = 1
Packet Size = 1024
Momentary freq = 192008 Hz (0x18.0040)
Feedback Format = 8.16
Packet Size = 0
Momentary freq = 192000 Hz (0x18.0000)
Interface 1
Altset 1
Format: S32_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000
Data packet interval: 125 us


However it doesn’t display bit depth. XBMC's GUI can show the streaming rate, which for Redbook PCM is ~1.4M and 24/96 is ~4.5M, indicating the software recognizes the full 24 bits. I don’t know if that gets to the DAC. Do any command line gurus know if it's possible to display a stream's bit depth too? Thx in advance....
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Old 14th April 2013, 08:47 PM   #2104
phofman is offline phofman  Czech Republic
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Format: S32_LE

Your DAC receives 32bit samples. Your original 24bits are appended with one extra byte and the resultant 32bits are read by the USB controller.
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Old 14th April 2013, 10:44 PM   #2105
rdf is offline rdf  Canada
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Quote:
Originally Posted by phofman View Post
Format: S32_LE
Thanks phofman, I wondered about that. The new audio engine returns the same result with nothing playing so wasn't surre if it represents a description of the card's capablities:

Playback:
Status: Stop
Interface 1
Altset 1
Format: S32_LE
Channels: 2
Endpoint: 1 OUT (ASYNC)
Rates: 44100, 48000, 88200, 96000, 176400, 192000
Data packet interval: 125 us

Though I can't complain if it is....
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Old 15th April 2013, 04:50 AM   #2106
phofman is offline phofman  Czech Republic
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Yes, that parameter describes the card capability. Some cards list two or more of them (e.g. S16_LE, S32_LE), in your case only 32bits are accepted. This is pretty much the most common value for 24bit-capable cards.

That means if the card is playing, it is receiving 32bit samples. Unless your chain decimates input samples to 16bits, you can be sure no information is lost. If you avoid dmix, rate plugin of alsa, and players which support 16bits only (such as old versions of mplayer), your chain keeps the bit depth.
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Old 15th April 2013, 05:05 AM   #2107
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Has anyone found a reliable passive crossover designer application in Linux?
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Old 15th April 2013, 01:17 PM   #2108
rdf is offline rdf  Canada
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Thanks again phofman, I did not know that. As far as I can tell XBMC defaults PAPlayer to a do-nothing configuration so it looks like the system is running 'bit perfect' after all. Not bad for plug and play free software.
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Old 15th April 2013, 03:19 PM   #2109
phofman is offline phofman  Czech Republic
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The new AudioEngine should be OK

e.g.

https://github.com/xbmc/xbmc/blob/ma...kALSA.cpp#L305
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Old 15th April 2013, 09:52 PM   #2110
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Quote:
Originally Posted by stochastic View Post
Has anyone found a reliable passive crossover designer application in Linux?
I've never looked. There are so many online tools out there...
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