Category Archives: ALSA

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Jack2 Audio Connection Kit

Jack2 is the connector for audio within and between computers.  It connects your audio soundcard to the guts of your computer using a simple to visualize jackfield, where you connect audio paths from one output to any number of inputs.  You can also connect several computers’ audio together over ethernet!  It is available for Linux (Ubuntu Studio), MacOS, and Windows!  It does not know multi-channel audio natively, so you have to hook up the left and the right ‘cables’ independently.

Jack Logo

 

 

My first exposure to Jack was back in Ubuntu 10.04 where I installed it manually in a system that had ALSA (Advanced Linux Sound Architecture) and an early version of Pulseaudio  installed.  It drove me crazy, no audio or audio that had dropouts.  Dozens of settings poorly documented.  AARRRRGH!

No longer! Ubuntu Studio comes with Jack2 already installed so all that grief is mostly behind you.  Many web sources tell you to get rid of Pulseaudio, but the case is not so compelling as it once was, but if low latency or several sound cards are in your plan, dump it.  Check out my article “Use Pulseaudio with Jack Audio Connection Kit?”

You should have your final soundcard(s) installed when you install Ubuntu-Studio so that it can pick up the cards automatically.  Jack comes with a little utility called qjackctl that lets you set all the necessary configuration that lets you correct much of what might not work right away.  No audio can usually be fixed with a command line utility called alsamixer because some sound card drivers set the volume to “0” not “11”.

There are packages from a site called KXStudio that make using Jack2 on Linux beautiful.  If you dive into KXStudio, you will not most of the Jack2 utilities like Patchage, qjackctl, etc.  I will have a script on this site soon that automates installing all these Uber Cool features.

Once you can hook up an audio editor like Audacity to the audio outputs and connect a parametric equalizer to the microphone inputs and the equalizer to Audacity inputs, along a  Jack meterbridge or spectrum analyzer you can see the power of this system. Jack can hook up Lapsda and .vst plugins for a multitude of effects.

NetJack is a way to hook up several computers’ audio  together via ethernetwith one master computer connecting to another, or several others.  This can work over a typical quiet office network, but the NetJack audio should be on its own network with no competing uses of the bandwidth.  If there is too much audio flying around even a 1 GB network can get overloaded.

So, the possibility of shipping audio around between workstations and a server is a real possibility, getting rid of lots of conventional cabling, and removing hundreds or thousands of places where the audio can get degraded.

 


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Use PulseAudio with Jack Audio Connection Kit?

Ubuntu Studio 14.04 uses Pulseaudio -> Alsa -> Jack as the connection interface for audio devices.  Pulseaudio is a very simple interface, and with it most audio cards just “show up” and play with Jack as the pulseaudio-sink and pulseaudio-source devices on the Jack patchbay.

In the olden days (Ubuntu Studio 10.04 and before) Pulseaudio was  buggy and not worth the effort to deal with the bugs.  Pulseaudio is now much more mature, and for a single sound card machine makes it much more likely that you will have Jack working right away.  If you are using Debian or regular Ubuntu, you will need a Pulseaudio plugin to hook it up with Jack.  I have not used the plugin as it is all nicely done in Ubuntu Studio.

Alsa is perfectly capable of connecting sound cards to Jack, with infinitely more flexibility, and (unfortunately) with more complexity.  Remember to turn the volume controls up in alsamixer!

There still remain some reasons to dump Pulseaudio:

  • Pulseaudio works best with a single sound card – if you have an in-computer card and a USB card and want to use both, Pulseaudio is complicated at least and may not let you use the second card. (I have not been successful, but I didn’t try very hard)
  • Pulseaudio devices want to hook up to stuff in the patchbay, and I have not figured how to keep them from automatically doing so.
  • Pulseaudio adds latency to the audio chain.  If you are just recording and playing back stuff and “real time” audio is not important, this might be insignificant.
  • Pulseaudio and Rivendell get in the way of each other.  Rivendell wants to have multiple audio inputs and multiple outputs, and that can be a problem with Pulseaudio if they are on different cards.
  • Pulseaudio devices Pulseaudio-sink and Pulseaudio-source hide the names of the actual sound devices, so they can be confusing when patching.
  • Pulseaudio hides and plays with some sound card settings in Alsa, so special configurations might just get reset to the defaults at next boot.

The reasons to keep Pulseaudio:

  • Alsa can be tricky to get all your audio devices working right unless you are happy to use the command line.
  • Ubuntu Studio comes with Pulseaudio installed and working, and dumping it can cause your installation to stop working until you figure out what Alsa settings for your sound card are undone.
  • There are some tricks to getting Pulseaudio to uninstall or to disable it. (It keeps coming back)
  • Pulseaudio now keeps a simple setup simple (except for those crazy patchbay devices)

Assuming you want to remove Pulseaudio, here is what you do:

From hecticgeek.com:

1. First let’s remove PulseAudio from your Ubuntu OS. I don’t remember since when Ubuntu used to come installed it by default, but for the recent versions such as: 12.04 Precise Pangolin, 11.10 Oneiric Ocelot, 11.04 Natty Narwhal, 10.10 and 10.04 the below command should remove it.

sudo apt-get -y autoremove pulseaudio

2. Now do a reboot since PulseAudio daemon (system service) is also running from the background. So it’s better to let the OS update everything.

3. You need the package alsa-tools, but that is already installed in Ubuntu-Studio, but not in regular Ubuntu.

4.  The script I will be publishing later will do this all automagically.

If you just want to just disable PulseAudio, you can edit the config file

1.   Copy /etc/pulseaudio/client.conf for a backup

sudo cp /etc/pulseaudio/client.conf /etc/pulseaudio/client.conf.orig

2.  Modify /etc/pulse/client.conf  the line   ; autospawn = yes to autospawn=np

sudo sed  s/; autospawn = yes/autospawn = no/ /etc/pulseaudio/client.conf

3.  Reboot or kill the pulseaudio job.


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Hardware for Audio – Server and Workstation

The Workstation

A Rivendell workstation with Jack2 and Netjack to work with a server needs a reliable motherboard with an X64 processor  with two to four cores, Several Gigs (3?) of Memory, and if to be used with a server for audio storage and database, probably 120 Gigs of SSD.     If the machine will be in a playout or editing environment, an SSD is important for fast boot  and fast loading of applications. The $50 a little SSD costs is well worth it.  An additional hard drive is needed to keep keep work files in the /home folder.  If you have a good server, you don’t need a big hard drive unless you want to duplicate the library and database on the workstation (this is tricky because they need to be kept sync’ed)

If you work with a server, you need a good quality Gigabit network card which you will set up for STATIC ADDRESSING.

You need a good sound card fully rated for ALSA compatibility.  I have used M-Audio hardware with good results, particularly the Delta 1010 cards and the all of the 17xx cards work well too.  Ubuntu studio 14.04 has also learned to play nice with M-Audio Fast Track 8R USB rack mounted box. (earlier versions did not)  Rivendell loves the Audio Sciences cards, but they are pricey.

If the workstation is in the studio, you also want high volume LOW NOISE fans. Bigger cabinets seem to have quieter fans because they use larger 120 mm fans that move more air with slower blades. You should also use a good quality power supply and UPS.  The UPS should be connected to the computer USB for graceful shutdown when the power goes out, and stays out.

The current version of Rivendell playout has a fixed window size so don’t go crazy on resolution or the control window will be too small.  (I have heard that this is likely to change in the next major revision).   Your video card does not need to be anything special, motherboard cards work fine.  rdAirplay will work with a touchscreen, and there are many that work with Ubuntu-Studio, but not all.  Your touchscreen mileage may vary.  You are looking for high reliability, not blazing performance. Do not overclock.

Rivendell works with audio switchers such as the Broadcast Tools SS 8.2, and with digital IO cards that talk by RS-232 serial ports.  It would be nice if the motherboard had an RS-232 port, but a high quality USB-RS-232 converter will work.  There are cheap converters that won’t work because they need a special driver that might not be available in Linux.  The machines that will be running RdCatch and RdAirplay will need this if you need these outputs to switch satellite receivers and such.  (Audio switchers may be unnecessary if you have enough inputs and outputs on your soundcards when running Jack2.)

The Server

A server for Rivendell should have similar computing  performance to the workstation, and should have a reasonable amount of memory on a multi-processor X64 chip, with four or more gigs of memory.  Hard drives should start with a 128 Gig SSD for the operating system, and about 2 TB or more of high quality hard drives for audio and database.

You should have two or three Gigabyte Ethernet ports on this machine.

It theoretically could be a “headless” machine, but some of the audio applications just really need GUI interfaces.  Sharing a monitor, mouse and keyboard with a KVM switch with another machine (such as a standby server) would be useful.   Be careful that the KVM switch and the motherboard have the same mouse and keyboard connectors.  USB to DIN adapters generally don’t work on KVM switches. No fancy video card is needed.

If this will be the “master control for audio” it will need a good ALSA compatible sound card with as many output channels as you will have outputs.  The server should have at least a 2 TB  USB removable drive or a Network Attached Storage device for backups.  You may have trouble finding servers that are quiet enough for the average station.  If you will be running the servers in a server closet, I recommend recently pulled 1U to 4u servers with dual power supplies. They will, however, be much too noisy for an office or studio environment.  You probably can’t afford them new, but used are inexpensive, just make sure you get multiprocessor X64 machines with enough memory

Your “music” ethernet network should be built with good Cat6 cables – any that go through the ceilings or floors should be ‘plenum’ rated.  Use high quality gigabit switches.  You probably can do without managed switches unless you have a lot of workstations, and then we have to tune things that I haven’t had to do yet.

It is possible to set up a server standby system for Rivendell, where you have two identical servers for Rivendell and the audio store or the database are kept up to date on both.  This way a failure will not put you off the air until a new server can be configured.  Similarly, you should keep your workstations as close to identical as possible  so you can switch over quickly in the case of an equipment failure.

If you are doing hot standby  servers, it would make sense to have two independent UPS systems – one for each server, and a ups for each workstation.  The idea is “no single point of failure”!  This is where the use of a real router (not bestbuy specials, but microtik or cisco) become important.

When you set up Ubuntu studio on these machines make sure you choose to add .mp3 codec and use LVM.  The account you use to setup will be the main “SUDOER” account.  Use a real password and require it to be entered.  It might make sense to encrypt the main account’s /home folder.

The server might be called on to do more than switch audio, serve the databases, and stream.  You may want to run the station’s phone system using freeswitch, or at least the phone interfaces to the studio.  It may make sense to put these into separate “boxes” using Oricle’s Virtualbox or the more sophisticated OpenStack. If you are thinking about using openstack, you will need at least one processor per “node” so a six or eight processor computer for the server makes sense, along with more memory, as each node has its “own” memory.


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