annotate doc/command_line_usage.rst @ 423:88e99cfd9c4c

Refactor io

``auditok`` can also be used from the command-line. For more information about
parameters and their description type:


.. code:: bash

    auditok -h

In the following we'll a few examples that covers most use-cases.


Read and split audio data online
--------------------------------

To try ``auditok`` from the command line with you voice, you should either
install `pyaudio <https://people.csail.mit.edu/hubert/pyaudio>`_ so that ``auditok``
can directly read data from the microphone, or record data with an external program
(e.g., `sox`) and redirect its output to ``auditok``.

Read data from the microphone (`pyaudio` installed):

.. code:: bash

    auditok

This will print the *id*, *start time* and *end time* of each detected audio
event. Note that we didn't pass any additional arguments to the previous command,
so ``auditok`` will use default values. The most important arguments are:


- ``-n``, ``--min-duration`` : minimum duration of a valid audio event in seconds, default: 0.2
- ``-m``, ``--max-duration`` : maximum duration of a valid audio event in seconds, default: 5
- ``-s``, ``--max-silence`` : maximum duration of a consecutive silence within a valid audio event in seconds, default: 0.3
- ``-e``, ``--energy-threshold`` : energy threshold for detection, default: 50


Read audio data with an external program
----------------------------------------

If you don't have `pyaudio`, you can use `sox` for data acquisition
(`sudo apt-get install sox`) and make ``auditok`` read data from standard input:

.. code:: bash

    rec -q -t raw -r 16000 -c 1 -b 16 -e signed - | auditok - -r 16000 -w 2 -c 1

Note that when data is read from standard input, the same audio parameters must
be used for both `sox` (or any other data generation/acquisition tool) and
``auditok``. The following table summarizes audio parameters.


+-----------------+------------+------------------+-----------------------+
| Audio parameter | sox option | `auditok` option | `auditok` default     |
+=================+============+==================+=======================+
| Sampling rate   | -r         | -r               |                 16000 |
+-----------------+------------+------------------+-----------------------+
| Sample width    | -b (bits)  | -w (bytes)       |                     2 |
+-----------------+------------+------------------+-----------------------+
| Channels        | -c         | -c               |                     1 |
+-----------------+------------+------------------+-----------------------+
| Encoding        | -e         | NA               | always a signed int   |
+-----------------+------------+------------------+-----------------------+

According to this table, the previous command can be run with the default
parameters as:

.. code:: bash

    rec -q -t raw -r 16000 -c 1 -b 16 -e signed - | auditok -i -

Play back audio detections
--------------------------

Use the ``-E`` option (for echo):

.. code:: bash

    auditok -E
    # or
    rec -q -t raw -r 16000 -c 1 -b 16 -e signed - | auditok - -E

The second command works without further argument because data is recorded with
``auditok``'s default audio parameters . If one of the parameters is not at the
default value you should specify it alongside ``-E``.



Using ``-E`` requires `pyaudio`, if it's not installed you can use the ``-C``
(used to run an external command with detected audio event as argument):

.. code:: bash

    rec -q -t raw -r 16000 -c 1 -b 16 -e signed - | auditok - -C "play -q {file}"

Using the ``-C`` option, ``auditok`` will save a detected event to a temporary wav
file, fill the ``{file}`` placeholder with the temporary name and run the
command. In the above example we used ``-C`` to play audio data with an external
program but you can use it to run any other command.


Print out detection information
-------------------------------

By default ``auditok`` prints out the **id**, the **start** and the **end** of
each detected audio event. The latter two values represent the absolute position
of the event within input stream (file or microphone) in seconds. The following
listing is an example output with the default format:

.. code:: bash

    1 1.160 2.390
    2 3.420 4.330
    3 5.010 5.720
    4 7.230 7.800

The format of the output is controlled by the ``--printf`` option. Alongside
``{id}``, ``{start}`` and ``{end}`` placeholders, you can use ``{duration}`` and
``{timestamp}`` (system timestamp of detected event) placeholders.

Using the following format for example:

.. code:: bash

    auditok audio.wav  --printf "{id}: [{timestamp}] start:{start}, end:{end}, dur: {duration}"

the output would be something like:

.. code:: bash

    1: [2021/02/17 20:16:02] start:1.160, end:2.390, dur: 1.230
    2: [2021/02/17 20:16:04] start:3.420, end:4.330, dur: 0.910
    3: [2021/02/17 20:16:06] start:5.010, end:5.720, dur: 0.710
    4: [2021/02/17 20:16:08] start:7.230, end:7.800, dur: 0.570


The format of ``{timestamp}`` is controlled by ``--timestamp-format`` (default:
`"%Y/%m/%d %H:%M:%S"`) whereas that of ``{start}``, ``{end}`` and ``{duration}``
by ``--time-format`` (default: `%S`, absolute number of seconds). A more detailed
format with ``--time-format`` using `%h` (hours), `%m` (minutes), `%s` (seconds)
and `%i` (milliseconds) directives is possible (e.g., "%h:%m:%s.%i).

To completely disable printing detection information use ``-q``.

Save detections
---------------

You can save audio events to disk as they're detected using ``-o`` or
``--save-detections-as``. To get a uniq file name for each event, you can use
``{id}``, ``{start}``, ``{end}`` and ``{duration}`` placeholders. Example:


.. code:: bash

    auditok --save-detections-as "{id}_{start}_{end}.wav"

When using ``{start}``, ``{end}`` and ``{duration}`` placeholders, it's
recommended that the number of decimals of the corresponding values be limited
to 3. You can use something like:

.. code:: bash

    auditok -o "{id}_{start:.3f}_{end:.3f}.wav"


Save whole audio stream
-----------------------

When reading audio data from the microphone, you most certainly want to save it
to disk. For this you can use the ``-O`` or ``--save-stream`` option.

.. code:: bash

    auditok --save-stream "stream.wav"

Note this will work even if you read data from another file on disk.


Plot detections
---------------

Audio signal and detections can be plotted using the ``-p`` or ``--plot`` option.
You can also save plot to disk using ``--save-image``. The following example
does both:

.. code:: bash

    auditok -p --save-image "plot.png" # can also be 'pdf' or another image format

output example:

.. image:: figures/example_1.png

Plotting requires `matplotlib <https://matplotlib.org/stable/index.html>`_.