Merge pull request #222 from jamessam/gh-pages

add note about dither methods to the audio recipes.
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Katherine Frances Nagels 2017-08-21 12:49:09 +12:00 committed by GitHub
commit ef6e5d07dc

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<dl>
<dt>ffmpeg</dt><dd>starts the command</dd>
<dt>-i <i>input_file</i></dt><dd>path and name of the input file</dd>
<dt>-write_id3v1 <i>1</i></dt><dd>Write ID3v1 tag. This will add metadata to the old MP3 format, assuming youve embedded metadata into the WAV file.</dd>
<dt>-id3v2_version <i>3</i></dt><dd>Write ID3v2 tag. This will add metadata to a newer MP3 format, assuming youve embedded metadata into the WAV file.</dd>
<dt>-dither_method <i>modified_e_weighted</i></dt><dd>Dither makes sure you dont unnecessarily truncate the dynamic range of your audio.</dd>
<dt>-write_id3v1 <i>1</i></dt><dd>This will write metadata to an ID3v1 tag at the head of the file, assuming youve embedded metadata into the WAV file.</dd>
<dt>-id3v2_version <i>3</i></dt><dd>This will write metadata to an ID3v2.3 tag at the tail of the file, assuming youve embedded metadata into the WAV file.</dd>
<dt>-dither_method <i>rectangular</i></dt><dd>Dither makes sure you dont unnecessarily truncate the dynamic range of your audio.</dd>
<dt>-out_sample_rate <i>48k</i></dt><dd>Sets the audio sampling frequency to 48 kHz. This can be omitted to use the same sampling frequency as the input.</dd>
<dt>-qscale:a <i>1</i></dt><dd>This sets the encoder to use a constant quality with a variable bitrate of between 190-250kbit/s. If you would prefer to use a constant bitrate, this could be replaced with <code>-b:a 320k</code> to set to the maximum bitrate allowed by the MP3 format. For more detailed discussion on variable vs constant bitrates see <a href="https://trac.ffmpeg.org/wiki/Encode/MP3" target="_blank">here.</a></dd>
<dt><i>output_file</i></dt><dd>path and name of the output file</dd>
</dl>
<p>A couple notes<p>
<ul>
<li>About ID3v2.3 tag: ID3v2.3 is better supported than ID3v2.4, FFmpeg's default ID3v2 setting.<li>
<li>About dither methods: FFmpeg comes with a variety of dither algorithms, outlined in the <a href="https://ffmpeg.org/ffmpeg-resampler.html" target="_blank" rel="noopener noreferrer">official docs</a>, though some may lead to unintended, drastic digital clipping on some systems.</li>
</ul>
<p class="link"></p>
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<dt>-i <i>input_file</i></dt><dd>path and name of the input file</dd>
<dt>-c:a aac</dt><dd>sets the audio codec to AAC</dd>
<dt>-b:a 128k</dt><dd>sets the bitrate of the audio to 128k</dd>
<dt>-dither_method modified_e_weighted</dt><dd>Dither makes sure you dont unnecessarily truncate the dynamic range of your audio.</dd>
<dt>-dither_method rectangular</dt><dd>Dither makes sure you dont unnecessarily truncate the dynamic range of your audio.</dd>
<dt>-ar 44100</dt><dd>sets the audio sampling frequency to 44100 Hz, or 44.1 kHz, or “CD quality”</dd>
<dt><i>output_file</i></dt><dd>path and name of the output file</dd>
</dl>
<p>A note about dither methods. FFmpeg comes with a variety of dither algorithms, outlined in the <a href="https://ffmpeg.org/ffmpeg-resampler.html" target="_blank" rel="noopener noreferrer">official docs</a>, though some may lead to unintended, not-subtle digital clipping on some systems.</p>
<p class="link"></p>
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