start trim start silence

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Andrew Weaver 2019-01-28 16:56:15 -08:00
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<label class="recipe" for="trim_start_silence">Trim silence from beginning of an audio file</label>
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<h3>Remove silent portions at the beginning of an audio file</h3>
<p><code>ffmpeg -i <em>input_file</em>-af silenceremove=start_threshold=-57dB:start_duration=1:start_periods=1<em>output_file</em></code></p>
<p>This command will automatically remove silence at the beginning of an audio file. The threshold for what qualifies as silence can be changed - this example uses anything under -57dB, which is a decent level for accounting for analogue hiss.</p>
<dl>
<dt>ffmpeg</dt><dd>starts the command</dd>
<dt>-i <em>input_file</em></dt><dd>path, name and extension of the input file (e.g. input_file.wav)</dd>
<dt>-af silenceremove</dt><dd>applies the silence remove filter</dd>
<dt>start_threshold=-57dB</dt><dd>tells the filter the threshold for what to call 'silence' for the purpose of removal. This can be increased or decreased as necessary.</dd>
<dt>start_duration=1</dt><dd>This tells the filter how much non-silent audio must be detected before it stops trimming. With a value of <code>0</code> the filter would stop after detecting any non-silent audio. A setting of <code>1</code> allows it to continue trimming through short 'pops' such as those caused by engaging the playback device, or the recorded sound of a microphone being plugged in.</dd>
<dt>start_periods=1</dt><dd>This tells the filter to trim the first example of silence it discovers from the beginning of the file. This value could be increased to remove subsequent silent portions from the file if desired.</dd>
<dt><em>output_file</em></dt><dd>path, name and extension of the output file (e.g. output_file.wav).</dd>
</dl>
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<h2 id="interlacing">Work with interlaced video</h2>