ecasound

06.10.2001

NAME

SYNOPSIS

DESCRIPTION

Ecasound is a software package designed for multitrack audio processing. It can be used for simple tasks like audio playback, recording and format conversions, as well as for multitrack effect processing, mixing, recording and signal recycling. Ecasound supports a wide range of audio inputs, outputs and effect algorithms. Several open-source audio packages, like for instance ALSA, OSS, mpg123, lame, libaudiofile and MikMod, are directly supported. One of the advantages of ecasound's chain-based design is that effects can easily be combined both in series and in parallel. Oscillators and MIDI-CCs can be used for controlling effect parameters. Included user-interfaces are ecasound - a versatile console mode interface, qtecasound - a Qt-based X-interface and various command-line utils suitable for batch processing.

OPTIONS

Note! All options except those mentioned in Global options, can be used in ecasound chainsetup files (.ecs).

GLOBAL OPTIONS

-c

Starts ecasound in interactive mode. In interactive mode you can control ecasound with simple commands ("start", "stop", "pause", etc.). See ecasound-iam(1).

-C

Disables ecasound's interactive mode (see '-c').

-d:debug_level

Set the debug level to 'debug_level'. This a bitmasked value, that defaults to 3. See ECA_DEBUG class documentation for more detailed info about various debug_level values.

-D

Print all debug information to stderr (unbuffered, plain output without ncurses).

-q

Quiet mode, no output. Same as -d:0.

--help

Show this help.

--version

Print version info.

-s[:]chainsetup-file

Create a new chainsetup from file 'chainsetup-file' and add it to the current session. Chainsetup can contain inputs, outputs, chains, effects, controllers, etc. A session, on the other hand, contains all the chainsetups. Although only one chainsetup can be connected at a time, you can switch between them on-the-fly.

GENERAL CHAINSETUP OPTIONS

-a:chainname1, chainname2, ...

Selects active signal chains. All effects, inputs and outputs following this '-a' option are assigned to selected chains (until a new -a option is specified). If no -a option has been given, chain 'default' is used instead. Chain name 'all' is also reserved and means that all chains are selected. By giving multiple -a options, you can control to which chains effects, inputs and outputs are assigned to. Look at the EXAMPLES section for more detailed info about the usage of this option.

-n:name

Sets the name of chainsetup to 'name'. If not specified, defaults either to "command-line-setup" or to the file name from which chainsetup was loaded. Whitespaces are not allowed.

-sr:sample_rate

Sets internal sampling rate. This can be used to improve realtime performance or to avoid resampling. Default is 44100 samples per second.

-x

Truncate outputs. All output object are opened in overwrite mode. Any existing files will be truncated.

-X

Open outputs for updating. Ecasound opens all outputs - if target format allows it - in readwrite mode.

-z:feature

Enables 'feature'. Most features can be disabled using notation -z:nofeatures. '-z:db,dbsize' enables double-buffering for audio objects that support it (dbzise=0 for default, otherwise buffer size in sample frames). '-z:nodb' disables double-buffering. '-z:intbuf' and '-z:nointbuf' control whether extra internal buffering is allowed for realtime devices. Disabling this can reduce latency times in some situations. With '-z:xruns', processing will be halted if an under/overrun occurs. '-z:psr' enables the precise-sample-rates mode for OSS-devices. See ecasoundrc(5).

CHAINSETUP BUFFERING AND PERFORMANCE OPTIONS

-B:buffering_mode

Selects the default buffering mode. Mode is one of: 'auto' (default), 'nonrt', 'rt', 'rtlowlatency'.

-b:buffer size

Sets the size of buffer in samples (must be an exponent of 2). This is quite an important option. For real-time processing, you should set this as low as possible to reduce the processing delay. Some machines can handle buffer values as low as 64 and 128. In some circumstances (for instance when using oscillator envelopes) small buffer sizes will make envelopes act more smoothly. When not processing in real-time (all inputs and outputs are normal files), values between 512 - 4096 often give better results. Default is 1024.

-m:mix-mode

Forces ecasound to use mix mode 'mix_mode'. 'auto' = automatic (default), 'simple' = only one input/chain/output and 'normal' = normal single-threaded mode. In most cases, ecasound is able to find out the correct mode automatically.

-r:sched_priority

Use realtime scheduling policy (SCHED_FIFO). This is impossible if ecasound doesn't have root priviledges. Beware! This gives better performance, but can cause total lock-ups if something goes wrong. The 'sched_priority' can be omitted (0=omitted). If given, this is the static priority to the highest priority ecasound thread. Other ecasound threads run with priority 'sched_priority-1...n'. Value '-1' can be used to disable raised-priority mode.

PROCESSING CONTROL

-t:seconds

Sets processing time in seconds (doesn't have to be an integer value). If processing time isn't set, engine stops when all inputs are finished. This option is equivalent to the 'cs-set-length' EIAM command.

-tl

Enables looping. When processing is finished, engine will start again from the initial position. This option is equivalent to the 'cs-loop' EIAM command.

INPUT/OUTPUT SETUP

See ecasound user's guide for more detailed documentation.

-f:sample_format,channel,sample-rate,interleaving

Sets default sampling parameters. These are used for all following input and output files or until another -f is specified. If no -f option is present, ecasound uses s16_le/2ch/44100/interleaved as the default value. Some audio objects may override this altogether (for instance, RIFF WAVE inputs and outputs).

Sample format is given as a a formatted string. The first letter is either "u", "s" and "f" (unsigned, signed, floating point). The following number specifies sample size in bits. If sample is little endian, "_le" is added to the end. Similarly if big endian, "_be" is added. If endianess is not specified, host byte-order is used. Currently supported formats are "u8" (same as "8"), "s16_le" (same as "16"), "s16_be", "s24_le", "s24_be", "s32_le", "s32_be", "f32_le" and "f32_be".

The 4th parameter 'interleaving' should either be 'i' (default) for interleaved stream format, or 'n' for noninterleaved.

-y:seconds

Sets starting position for last specified input/output. If you need more flexible control over audio objects, you should use the .ewf format.

-i[:]input-file-or-device

Specifies a new input source that is connected to all selected chains. Connecting multiple inputs to the same chain isn't possible. Input can be a a file, device or some other audio object (see below). If the input is a file, its type is determined using the file name extension. Currently supported formats are RIFF WAVE files (.wav), audio-cd tracks (.cdr), ecasound ewf-files (.ewf), RAW audio data (.raw) and MPEG files (.mp2,.mp3). Also, formats supported by the SGI audiofile library: AIFF (.aiff, .aifc, .aif) and Sun/NeXT audio files (.au, .snd). MikMod is also supported (.xm, .mod, .s3m, .it, etc). MIDI files (.mid) are supported using Timidity++. Similarly Ogg Vorbis (.ogg) can be read and written if ogg123 and vorbize tools are installed. Supported realtime devices are OSS audio devices (/dev/dsp*), ALSA audio and loopback devices. If no inputs are specified, the first non-option (doesn't start with '-') command line argument is considered to be an input.

-o[:]output-file-or-device

Works in the same way as the -i option. If no outputs are specified, the default output device is used (see ˜/.ecasoundrc). Note! you can't output to module formats supported by MikMod (this should be obvious) nor to ALSA's loopback device.

OBJECT TYPE SPECIFIC NOTES

ALSA devices

When using ALSA drivers, instead of a device filename, you need to use the following option syntax: -i[:]alsa,pcm_device_name. Note! Pcm device naming was introduced in ALSA 0.6.x (doesn't work with older ALSA versions; see below for the old syntax).

ALSA direct-gw and plugin access

It's also possible to use a specific card and device combination using the following notation: -i[:]alsahw,card_number,device_number,subdevice_number. The ALSA plugin layer works just like the normal ALSA pcm-devices, but with automatic sample rate and format conversions. Option syntax is -i[:]alsaplugin,card_number,device_number,subdevice_number.

ALSA loopback device

By using the ALSA loopback system, you can grab audio data from any other pcm device. Option syntax is -i[:]alsalb,card_number,device_number,subdevice_number. Note! Only works with ALSA 0.5.x and older.

aRts input/output

If enabled at compile-time, ecasound supports audio input and output using aRts audio server. Option syntax is -i:arts, -o:arts.

Ecasound Wave Files - .ewf

A simple wrapper class for handling other audio objects. See ecasound user's guide for more detailed information.

Loop device

Loop devices make it possible to route data between chains. Option syntax is -[io][:]loop,id_number. If you add a loop output with id '1', all data written to this output is routed to all loop inputs with id '1'. You can attach the same loop device to multiple inputs and outputs.

Null inputs/outputs

If you specify "null" or "/dev/null" as the input or output, a null audio device is created. This is useful if you just want to analyze sample data without writing it to a file. There's also a realtime variant, "rtnull", which behaves just like "null" objects, except all i/o is done at realtime speed.

System standard streams and named pipes

You can use standard streams (stdin and stdout) by giving "stdin" or "stdout" as the file name. Audio data is assumed to be in raw/headerless (.raw) format. If you want to use named pipes, create them with the proper file name extension before use.

Typeselect - overriding object type settings

The special 'typeselect' object type can be used to override how ecasound maps filename extensions and object types. For instance "ecasound -i typeselect,.mp3,an_mp3_file.wav -o /dev/dsp". would play the file 'an_mp3_file.wav' as an mp3-file and not as an wav-file as would happen without typeselect.

MIDI SETUP

-Md:rawmidi,device_name

Sets the active MIDI-device. 'device_name' can be anything that can be accessed using the normal UNIX file operations and produces raw MIDI bytes. Valid devices are for example OSS rawmidi devices (/dev/midi00), named pipes (see mkfifo(1) man page), and normal files. If no MIDI-device is specified, the default MIDI-device is used (see ecasoundrc(5)).

-Mms:device_id

Sends MMC start and stop to MIDI device-id 'device_id'.

-Mss

Sends MIDI-sync to the selected MIDI-device. Note! Ecasound will not send MIDI-clock, but only start and stop messages.

EFFECT SETUP

PRESETS

Ecasound has a powerful effect preset system that allows you create new effects by combining basic effects and controllers. See ecasound user's guide for more detailed information.

-pf:preset_file.eep

Uses the first preset found from file 'preset_file.eep' as a chain operator.

-pn:preset_name

Find preset 'preset_name' from global preset database and use it as a chain operator. See ecasoundrc(5) for info about the preset database.

SIGNAL ANALYSIS

-ev

Analyzes sample data to find out how much the signal can be amplified without clipping. The resulting percent value can be used as a parameter to -ea and -eas effects. Also prints a statistics table containing info about stereo-image and how different sample values are used.

-ezf

Finds the optimal value for DC-adjusting. You can use the result as a parameter to -ezx effect.

GENERAL SIGNAL PROCESSING ALGORITHMS

-eS:stamp-id

Audio stamp. Takes a snapshot of passing audio data and stores it using id 'stamp-id' (integer number). This data can later be used by controllers and other operators.

-ea:amplify-%

Amplifies signal by amplify-% percent.

-eac:amplify-%,channel

Amplifies signal of channel 'channel' by amplify-% percent. 'channel' ranges from 1...n where n is the total number of channels.

-eaw:amplify-%,max-clipped-samples

Amplifies signal by amplify-% percent. If number of consecutive clipped samples (resulting sample has the largest amplitude possible) reaches 'max-clipped-samples', a warning will be issued.

-eal:limit-%

Limiter effect. Limits audio level to 'limit-%'.

-ec:rate,threshold-%

Compressor (a simple one). 'rate' is the compression rate in decibels ('rate' dB change in input signal causes 1dB change in output). 'threshold' varies between 0.0 (silence) and 1.0 (max amplitude).

-eca:peak-level-%, release-time-sec, fast-crate, crate

A more advanced compressor (original algorithm by John S. Dyson). If you give a value of 0 to any parameter, the default is used. 'peak-level-%' essentially specifies how hard the peak limiter is pushed. The default of 69% is good. 'release_time' is given in seconds. This compressor is very sophisticated, and actually the release time is complex. This is one of the dominant release time controls, but the actual release time is dependent on a lot of factors regarding the dynamics of the audio in. 'fastrate' is the compression ratio for the fast compressor. This is not really the compression ratio. Value of 1.0 is infinity to one, while the default 0.50 is 2:1. Another really good value is special cased in the code: 0.25 is somewhat less than 2:1, and sounds super smooth. 'rate' is the compression ratio for the entire compressor chain. The default is 1.0, and holds the volume very constant without many nasty side effects. However the dynamics in music are severely restricted, and a value of 0.5 might keep the music more intact.

-enm:threshold-level-%,pre-hold-time-msec,attack-time-msec,post-hold-time-msec,release-time-msec

Noise gate. Supports multichannel processing (each channel processed separately). When signal amplitude falls below 'threshold_level_%' percent (100% means maximum amplitude), gate is activated. If the signal stays below the threshold for 'th_time' ms, it's faded out during the attack phase of 'attack' ms. If the signal raises above the 'threshold_level' and stays there over 'hold' ms the gate is released during 'release' ms.

-ei:pitch-shift-%

Pitch shifter. Modifies audio pitch by altering its length.

-epp:right-%

Normal pan effect. Balance value of 0 means to pan signal fully left and 100 fully right. If the panned signal is a stereo signal, left and right channels aren't mixed together. Use the -erm and -erc effects to force conversion to mono before panning.

-ezx:left-dc-fix-value,right-dc-fix-value

Adjusts the signal DC by 'dc-fix-value'. Use -ezf to find the optimal value.

ENVELOPE MODULATION

-eemb:bpm,on-time-%

Pulse gate (pulse frequency given as beats-per-minute).

-eemp:freq-Hz,on-time-%

Pulse gate.

-eemt:bpm,depth-%

Tremolo effect (tremolo speed given as beats-per-minute).

FILTER EFFECTS

-ef1:center_freq, width

Resonant bandpass filter. 'center_freq' is the center frequency. Width is specified in Hz.

-ef3:cutoff_freq, reso, gain

Resonant lowpass filter. 'cutoffr_freq' is the filter cutoff frequency. 'reso' means resonance. Usually the best values for resonance are between 1.0 and 2.0, but you can use even bigger values. 'gain' is the overall gain-factor. It's a simple multiplier (1.0 is the normal level). With high resonance values it often is useful to reduce the gain value.

-ef4:cutoff, resonance

Resonant lowpass filter (3rd-order, 36dB, original algorithm by Stefan M. Fendt). Simulates an analog active RC-lowpass design. Cutoff is a value between [0,1], while resonance is between [0,infinity).

-efa:delay-samples,feedback-%

Allpass filter. Passes all frequencies with no change in amplitude. However, at the same time it imposes a frequency-dependent phase-shift.

-efc:delay-samples,radius

Comb filter. Allows the spikes of the comb to pass through. Value of 'radius' should be between [0, 1.0).

-efb:center-freq,width

Bandpass filter. 'center_freq' is the center frequency. Width is specified in Hz.

-efh:cutoff-freq

Highpass filter. Only frequencies above 'cutoff_freq' are passed through.

-efi:delay-samples,radius

Inverse comb filter. Filters out the spikes of the comb. There are 'delay_in_samples-2' spikes. Value of 'radius' should be between [0, 1.0). The closer it is to the maximum value, the deeper the dips of the comb are.

-efl:cutoff-freq

Lowpass filter. Only frequencies below 'cutoff_freq' are passed through.

-efr:center-freq,width

Bandreject filter. 'center_freq' is the center frequency. Width is specified in Hz.

-efs:center-freq,width

Resonator. 'center_freq' is the center frequency. Width is specified in Hz. Basicly just another resonating bandpass filter.

CHANNEL MIXING / ROUTING

-erc:from-channel, to-channel

Copy channel 'from_channel' to 'to_channel'. If 'to_channel' doesn't exist, it is created. Channel indexing is started from 1.

-erm:to-channel

Mix all channels to channel 'to_channel'. If 'to_channel' doesn't exist, it is created. Channel indexing is started from 1.

TIME-BASED EFFECTS

-etc:delay-time-msec,variance-time-samples,feedback-%,lfo-freq

Chorus.

-etd:delay-time-msec,surround-mode,number-of-delays,mix-%,feedback-%

Delay effect. 'delay time' is the delay time in milliseconds. 'surround-mode' is a integer with following meanings: 0 = normal, 1 = surround, 2 = stereo-spread. 'number_of_delays' should be obvious. Beware that large number of delays and huge delay times need a lot of CPU power. 'mix-%' determines how much effected (wet) signal is mixed to the original. 'feedback-%' represents how much of the signal is recycled in each delay or, if you prefer, at what rate the repeated snippet of delayed audio fades. Note that sufficiently low feedback values may result in a number of audible repetitions lesser than what you have specified for 'number_of_delays', especially if you have set a low value for 'mix-%'. By default the value for this parameter is 100% (No signal loss.).

-ete:room_size,feedback-%,wet-%

A more advanced reverb effect (original algorithm by Stefan M. Fendt). 'room_size' is given in meters, 'feedback-%' is the feedback level given in percents and 'wet-%' is the amount of reverbed signal added to the original signal.

-etf:delay-time-msec

Fake-stereo effect. The input signal is summed to mono. The original signal goes to the left channels while a delayed version (with delay of 'delay time' milliseconds) is goes to the right. With a delay time of 1-40 milliseconds this adds a stereo-feel to mono-signals.

-etl:delay-time-msec,variance-time-samples,feedback-%,lfo-freq

Flanger.

-etm:delay-time-msec,number-of-delays,mix-%

Multitap delay. 'delay time' is the delay time in milliseconds. 'number_of_delays' should be obvious. 'mix-%' determines how much effected (wet) signal is mixed to the original.

-etp:delay-time-msec,variance-time-samples,feedback-%,lfo-freq

Phaser.

-etr:delay-time,surround-mode,feedback-%

Reverb effect. 'delay time' is the delay time in milliseconds. If 'surround-mode' is 'surround', reverbed signal moves around the stereo image. 'feedback-%' determines how much effected (wet) signal is fed back to the reverb.

LADSPA-PLUGINS

-el:plugin_unique_name,param-1,...,param-N

Ecasound supports LADSPA-effect plugins (Linux Audio Developer's Simple Plugin API). Plugins are located in shared library (.so) files in /usr/local/share/ladspa (configured in ecasoundrc(5)). One shared library file can contain multiple plugin objects, but every plugin has a unique plugin name. This name is used for selecting plugins. See LAD mailing list web site for more info about LADSPA. Other useful sites are LADSPA home page and LADSPA documentation.

-eli:plugin_unique_number,param-1,...,param-N

Same as above expect plugin's unique id-number is used. It is guaranteed that these id-numbers are unique among all LADSPA plugins.

GATE SETUP

-gc:start-time,len

Time crop gate. Initially gate is closed. After 'start-time' seconds has elapsed, gate opens and remains open for 'len' seconds. When closed, passing audio buffers are trucated to zero length.

-ge:open-threshold-%, close-thold-%,volume-mode

Threshold gate. Initially gate is closed. It is opened when volume goes over 'othreshold' percent. After this, if volume drops below 'cthold' percent, gate is closed and won't be opened again. If 'value_mode' is 'rms', average RMS volume is used. Otherwise peak average is used. When closed, passing audio buffers are trucated to zero length.

CONTROL ENVELOPE SETUP

Controllers can be used to dynamically change effect parameters during processing. All controllers are attached to the selected (=usually the last specified effect/controller) effect. The first three parameters are common for all controllers. 'fx_param' specifies the parameter to be controlled. Value '1' means the first parameter, '2' the second and so on. 'start_value' and 'end_value' set the value range. You really should see examples.html for some more info.

-kos:fx-param,start-value,end-value,freq,i-phase

Sine oscillator with frequency of 'freq' Hz and initial phase of 'i_phase' times pi.

-kog:fx-param,start-value,end-value,freq,mode,point-pairs,start-value,end-value,pos1,value1,...

Generic oscillator. Frequency 'freq' Hz, mode either '0' for static values or '1' for linear interpolation. 'point-pairs' specifies the number of 'posN' - 'valueN' pairs to include. 'start-value' and 'end-value' are used as border values. All 'posN' and 'valueN' must be between 0.0 and 1.0. Also, for all 'posNī values 'pos1 < pos2 < ... < posN' must be true.

-kf:fx-param,start-value,end-value,freq,mode,genosc-number

Generic oscillator. 'genosc_number' is the number of the oscillator preset to be loaded. Mode is either '0' for static values or '1' for linear interpolation. The location for the preset file is taken from ./ecasoundrc (see ecasoundrc(5)).

-kl:fx-param,start-value,end-value,time-seconds

Linear envelope that starts from 'start_value' and linearly changes to 'end_value' during 'time_in_seconds'. Can be used for fadeins and fadeouts.

-kl2:fx-param,start-value,end-value,1st-stage-length-sec,2nd-stage-length-sec

Two-stage linear envelope, a more versatile tool for doing fade-ins and fade-outs. Stays at 'start_value' for '1st_stage_length' seconds and then linearly changes towards 'end_value' during '2nd_stage_length' seconds.

-klg:fx-param,start-value,end-value,point_count,pos1,value1,...,posN,valueN

Generic linear envelope. This controller source can be used to map custom envelopes to chain operator parameters. All 'posX' parameters are given as seconds (from start of the stream). 'valueX' parameters must be in the range [0,1].

-km:fx-param,start-value,end-value,controller,channel

MIDI continuous controller (control change messages). Messages on the MIDI-channel 'channel' that are coming from controller number 'controller' are used as the controller source. The MIDI-device is specified in ./ecasoundrc (see ecasoundrc(5)). Defaults to /dev/midi.

-ksv:fx-param,start-value,end-value,stamp-id,rms-toggle

Volume analyze controller. Analyzes the audio stored in stamp 'stamp-id' (see '-eS:id' docs), and creates control data based on the results. If 'rms-toggle' is non-zero, RMS-volume is used to calculate the control value. Otherwise average peak-amplitude is used.

-kx

This is a special switch that can be used when you need to control controller parameters with another controller. When you specify -kx, the last specified controller will be set as the control target. Then you just add another controller as usual.

INTERACTIVE MODE

See ecasound-iam(1).

FILES

~/.ecasoundrc The default ecasound resource file. See ecasoundrc(5). man page.

*.ecs Ecasound Chainsetup files. Syntax is more or less the same as with command-line arguments.

*.ecp Ecasound Chain Preset files. Used for storing effect and chain operator presets. See ecasound user's guide for more better documentation.

*.ews Ecasound Wave Stats. These files are used to cache waveform data.

SEE ALSO

ecatools(1), ecasound-iam(1) ecasoundrc(5), "HTML docs in the Documentation subdirectory"

BUGS

See file BUGS. If ecasound behaves weirdly, try to increase the debug level to see what's going on.

AUTHOR

Kai Vehmanen, <kaiv@wakkanet.fi>