Ecasound documentation - examples

I've used the text-mode version (ecasound) in all these examples, but qtecasound - Qt-interface to ecasound - could have also been used. It understands the same command line paremeters as the text-mode version.

Format conversions

  1. ecasound -i:somefile.wav -o:somefile.cdr
  2. ecasound -i somefile.wav -o somefile.cdr

    These do the same thing, convert somefile.wav to somefile.cdr. As no chains are specified, default chain is used.

  3. ecasound -a:1,2 -i somefile.wav -a:1 -o somefile.cdr -a:2 -o somefile.mp3

    This is not a very useful example, but hopefully helps to understand the way chains work. First, two new chains 1 and 2 (you can also use strings: -a:some_name_with_no_whitespaces,some_other_name) are created. They are now the active chains. After this, input somefile.wav is connected to both these chains. The rest follows the same scheme. Chain 1 is set active and output somefile.cdr is attached to it. In the same way, somefile.mp3 is attached to chain 2.

  4. ecasound -c -i somefile.wav -o somefile.cdr
  5. qtecasound -i somefile.wav -o somefile.cdr

    Like before, but ecasound is now started in interactive mode. Specified or not, qtecasound is always started in interactive mode.

Realtime outputs (soundcard playback)

  1. ecasound somefile.wav
  2. ecasound -i somefile.wav
  3. ecasound -i:somefile.wav
  4. ecasound -i somefile.wav -o /dev/dsp

    If you haven't touched your ~/.ecasoundrc configuration file, these should all do the same thing, output somefile.wav to /dev/dsp using the default chain. If no inputs are specified, ecasound tries to use the first non-option argument on the command line as a default input. If no chains are specified, the chain default is created and set active. If no outputs are specified, the default-output defined in ~/.ecasoundrc is used. This is normally /dev/dsp.

  5. ecasound -i somefile.mp3 -o alsahw,0,0
  6. ecasound -i somefile.mp3 -o alsaplugin,0,0
  7. ecasound -i somefile.mp3 -o alsa,soundcard_name

    The ALSA drivers have a somewhat different option syntax. You first specify either "alsahw" (to indicate you want use the ALSA direct hw interface) or "alsaplugin" (for ALSA plugin layer), and then specify the card number and the device number (optionally also subdevice can be given). The plugin layer is able to handle some type conversions automatically. The third option is specific to ALSA 0.9.x (and newer). 'soundcard_name' must be defined in the ALSA configuration files (either ~/.asoundrc or the global settings file). Otherwise ALSA inputs/outputs work just like OSS-devices.

  8. mpg123 -s sometune.mp3 | ecasound -i:stdin -o alsahw,0,0

    Send the output of mpg123 to standard output (-s option) and read it from standard input with ecasound (-i:stdin option). If you want to use native ALSA support with OSS-programs, this is one way to do it easily. This can also be used to add effects to standard streams containing audio data.

Realtime inputs (recording from soundcard)

  1. ecasound -i:/dev/dsp0 -o somefile.wav
  2. ecasound -i:/dev/dsp0 -o somefile.wav -c
  3. ecasound -i alsahw,1,0 -o somefile.wav

    These are simple examples of recording. Notice that when recording it's often useful to run ecasound in interactive mode (-c).

Effect processing

    Ecasound is an extremely versatile tool when it comes to effect processing. After all, it was originally programmed for non-realtime dsp processing. Because of this, these examples just scratch the surface.

  1. ecasound -i somefile.mp3 -o /dev/dsp -ea:120
  2. ecasound -a:default -i somefile.mp3 -o /dev/dsp -ea:120

    Let's start with a simple one. These do the same thing: mp3 input, OSS output and an amplify effect, which amplifies the signal by 120%, are added to the default chain.

  3. ecasound -i somefile.mp3 -o /dev/dsp -etr:40,0,55 -ea:120

    Like the previous example, but now a reverb effect, with a delay of 40 milliseconds, surround disabled and mix-% of 55, is added to chain before the amplify effect. In other words the signal is first processed with the reverb and then amplified. This way you can add as many effects as you like. If you ran out of CPU power, you can always use output to a file.

  4. ecasound -a:1,2 -i somefile.mp3 -a:all -o /dev/dsp \
      -a:1 -etr:40,0,55 -ea:120 \
      -a:2 -efl:400

    Ok, let's do some paraller processing. This time two chains are created and the input file is assigned to both of them. The output file is assigned to a special chain called all. -a:1,2 would also work. This way we can use one signal in multiple chains and process each chains with different effects. You can create as many chains as you want.

Using controller sources with effects

  1. ecasound -i somefile.wav -o /dev/dsp -ef3:800,1.5,0.9 -kos:1,400,4200,0.2,0 -kos:2,0.1,1.5,0.15,0
  2. ecasound -i somefile.wav -o /dev/dsp -ef3:800,1.5,0.9 -km:1,400,4200,74,0 -km:2,0.1,1.5,71,0

    The first example uses two sine oscillators (-kos:parameter,range_low,range_high,speed_in_Hz,initial_phase) to control a resonant lowpass filter. The cutoff frequency varies betweeen 400 and 4200 Hz, while resonance varies between 0.1 and 1.5. The initial phase is 0 (times pi). The second example uses MIDI continuous controllers (-km:parameter,range_low,range_high,controller_number,midi-channel) as controller sources. The ranges are the same as in the in first example. Controller numbers used are 74 (cutoff) and 71 (resonance). In other words you can use your synth's cutoff and resonance knobs.

    It's also possible to control controllers with other controllers using the -kx option. Normally when you add a controller, you're controlling the last specified chain operator. -kx changes this. Let's take an example:

  3. ecasound -i file.wav -o /dev/dsp -ea:100 -kos:1,0,100,0.5,0 -kx -kos:4,0.1,5,0.5,0

    Same as before, but now another 0.5Hz sine oscillator is controlling the frequency of the first oscillator.

  4. ecasound -i file.wav -o /dev/dsp -ef3:1000,1.0,1.0 -kos:1,500,2000,1,0 \
    -kos:2,0.2,1.0,0.5,0 \
    -kx -km:1,0.1,1.5,2,0

    Ok, let's get real whacky. Here a 1Hz sine oscillator is assigned to the cutoff frequency, while other controller is controlling resonance. Now we add a MIDI-controller, that controls the second sine oscillator.

Multitrack recording

  1. ecasound -c -b:256 -r -f:16,2,44100 \
      -a:1 -i monitor-track.wav -o /dev/dsp \
      -a:2 -i /dev/dsp -o new-track.wav

    It really is this simple. To minimize syncronization problems, a small buffersize is set with -b:buffer_size_in_samples. This time I set it to 256 samples. To ensure flawless recording, runtime priority is risen with -r. Then a default sample format is set with -f:bits,channels,sample_rate. Now all that's left is to specify two chains: one for monitoring and one for recording. When using the above command, you need to have some way of monitoring the signal that's been recorded. A common way is to enable hw-monitoring (unmute/adjust the line-in level from your mixer app). If you want to use ecasound for monitoring, you have to add a separate chain for it:

  2. ecasound -c -b:256 \
      -a:1 -i monitor-track.wav \
      -a:2,3 -i /dev/dsp \
      -a:2 -o new-track.wav \
      -a:1,3 -o /dev/dsp

    One thing to note that there are some differences in how OSS soundcard drivers handle full-duplex (playback and recording at the same time) operation. Some drivers allow the same device to be opened multiple times (like in above example we open '/dev/dsp' once for recording and once for playback.

    You can always do test recordings until you find the optimal volume levels (using the soundcard mixer apps and adjusting source volume), but ecasound offers a better way to do this. This is a bit ugly, but what's most important, it works in text-mode:

  3. ecasound -c -f:16,2,44100 -a:1 -i /dev/dsp0 -o /dev/dsp3 -ev

    Basicly this just records from one OSS input, puts the signal through an analyze (-ev) effect and outputs to an OSS output. The secret here is that you can get volume statistics with the estatus (or es) command in interactive mode. Qtecasound also offers a estatus pushbutton. This way you can adjust the mixer settings, check the statistics (after which they're reseted), adjust again, check statistics, ... and so on. Newer ecasound versions (1.8.5 and newer) come with 'ecasignalview', which is a standalone app that can monitor signal level in realtime.


    Here's a few real-life mixdown examples.

  1. ecasound -c \
      -a:1 -i drums.wav \
      -a:2 -i synth-background.wav \
      -a:3 -i bass-guitar_take-2.ewf \
      -a:4 -i brass-house-lead.wav \
      -a:all -o /dev/dsp

    First of all, interactive-mode is selected with -c. Then four inputs (all stereo) are added. All four chains are then assigned to one output, which this time is the soundcard (/dev/dsp). That's all.

  2. ecasound -c -r -b:2048 \
      -a:1,5 -i drums.wav -ea:200 \
      -a:2,6 -i synth-background.wav -epp:40 -ea:120 \
      -a:3,7 -i bass-guitar_take-2.ewf -ea:75 \
      -a:4,8 -i brass-house-lead.wav -epp:60 -ea:50 \
      -a:1,2,3,4 -o /dev/dsp \
      -a:5,6,7,8 -o current_mix.wav

    This second example is more complex. The same inputs are used, but this time effects (amplify -ea:mix_percent and normal pan -epp:left_right_balance) are also used. First four chains are assigned to the soundcard output as in the first example, but now we also have another set of chains that are assigned to a WAVE file current_mix.wav. In this example, runtime priority is also risen with -r. A bigger buffersize is also used.

Cut, copy and paste

  1. ecasound -i bigfile.wav -o part1.wav -t:60.0
  2. ecasound -i bigfile.wav -y:60.0 -o part2.wav

    Here's a simple example where first 60 seconds of bigfile.wav is written to part1.wav and the rest to part2.wav. If you want to combine these files back to one big file:

  3. ecasound -i part2.wav -o part1.wav -y:500

    part2.wav is appended to part1.wav.

Multichannel processing

    You need to worry about channel routing only if input and output channel counts don't match. Here's how you divide a 4-channel audio file into 4 mono files.

  1. ecasound -a:1,2,3,4 -i 4-channel-file.raw \
      -a:1 -f:16,1,44100 -o mono-1.wav \
      -a:2 -f:16,1,44100 -o mono-2.wav -erc:2,1 \
      -a:3 -f:16,1,44100 -o mono-3.wav -erc:3,1 \
      -a:4 -f:16,1,44100 -o mono-4.wav -erc:4,1

Signal routing through external devices

  1. ecasound -c -b:128 -r -f:16,2,44100 \
      -a:1 -i source-track.wav -o /dev/dsp3 \
      -a:2 -i /dev/dsp0 -o target-track.wav

    So basicly, this is just like multirack recording. The only difference is that realtime input and output are externally connected.

Presets and LADSPA effect plugins

  1. ecasound -i null -o /dev/dsp -el:sine_fcac,440,1

    This produces a 440Hz sine tone (great for tuning your instruments!). For the above to work, LADSPA SDK needs to be installed (see

  2. ecasound -i:null -o:/dev/dsp -el:sine_fcac,880,1 -eemb:120,10 -efl:2000

    This results in audible metrome signal with tempo of 120BPM. Now the syntax might look a bit difficult for everyday use. Luckily ecasound's preset system will help in this situation. You can get the same exact result with:

  3. ecasound -i:null -o:/dev/dsp -pn:metronome,120

    See the file 'effect_presets' for a list of available effect presets. By default, location of this file is '/usr/local/share/ecasound/effect_presets'.