Using the Ecasound -t Parameter to Set Duration

In Ecasound, the -t command-line parameter allows users to set a strict limit on the running time of an audio processing session. By explicitly defining the processing duration in seconds, the -t option ensures that Ecasound automatically halts execution once the specified time elapses. This feature is essential for automating tasks, capturing timed recordings, slicing audio clips, and preventing infinite processing loops when handling live or continuous streams.

Syntax and Functionality

The syntax for constraining processing time is:

-t:seconds

When specified, Ecasound runs its active engine chain until it reaches the declared duration, after which it smoothly stops and terminates the process. The duration value represents standard real-time seconds and supports decimal values for fractional seconds (e.g., -t:10.5 runs for ten and a half seconds).

Common Use Cases

  1. Recording for a Fixed Length
    When recording from an open hardware input (such as an ALSA or JACK soundcard input), Ecasound will run indefinitely by default. Adding -t automatically stops the recording after the desired length.
ecasound -i alsahw:0,0 -o recording.wav -t:60

This command records 60 seconds of audio from the soundcard and saves it to recording.wav.

  1. Extracting and Slicing Audio Clips
    When paired with the start position parameter (-y), the -t parameter functions as a trimmer. For example, to extract a 15-second sample starting at minute 1 (60 seconds) of an audio file:
ecasound -i source.wav -y:60 -t:15 -o clip.wav
  1. Previewing and Testing Signal Chains
    When developing complex signal chains with multiple filters, LADSPA plugins, or effects, processing a large audio file completely can be slow. Using -t:10 lets you audition or verify the output without processing the entire input file.

Behavior with Shorter Inputs

If the source audio stream reaches an End-Of-File (EOF) condition before the specified duration is reached, Ecasound terminates naturally at the EOF. The -t parameter acts strictly as an upper bound (a timeout ceiling) rather than a pad, meaning it will not pad the output with silence if the input file is shorter than the defined duration.