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→Basic Format Conversion
<code>-i</code> specifies input file
<code>-i</code> specifies input file
The last argument is always the output file. Without specifying any codec or bit rate (see examples below), FFmpeg will encode the video using some arbitrary default settings.
The last argument is always the output file. Without specifying any codec or bit rate (see examples below), FFmpeg will encode the video (and audio, if included) using some arbitrary default settings, depending on the input file and output format.
===Encoding===
{{cmdline|ffmpeg -i input.mp4 -vcodec h264 -b:v 8M -r:v 25 -acodec aac -b:a 256k output.mp4}}
<code>-vcodec h264</code> specifies video codec. "h264" is a shorthand for FFmpeg's x264 encoder, it is (by default) interchangeable with "x264" or "libx264".
<code>-b:v 8M</code> sets the video bit rate, in bits per second. You can use "k" or "M" as shorthand for a thousand or a million respectively. See [[Video Codecs]] for help choosing a bit rate.
<code>-r:v 25</code> sets the video frame rate, in frames per second. By default, the frame rate of the original video is kept.
<code>-acodec aac</code> specifies audio codec. AAC is used by default if your output is a .mp4 file. For AVI the default is MP3.
<code>-b:a</code> sets the audio bit rate, in bits per second. Default for AAC is 128k.
===Remove audio from video file===
===Remove audio from video file===
<code>-b:v 8M</code> specifies video bit rate, in this case 8Mbit/s, which determines video quality.
<code>-b:v 8M</code> specifies video bit rate, in this case 8Mbit/s, which determines video quality.
Note: you can use <code>-c copy</code> to trim without re-encoding, but FFmpeg can only cut to the nearest keyframe, so the output may not be exactly the same length as specified.
Note: you can use <code>-c copy</code> to trim without re-encoding, but in this case FFmpeg can only cut to the nearest keyframe, so the output may not be exactly the same length as specified.
===Batching===
===Batching===
subprocess.run(f'ffmpeg -i "{inputFile}" -vcodec h264 -b:v 8M "{outputFile}"')
subprocess.run(f'ffmpeg -i "{inputFile}" -vcodec h264 -b:v 8M "{outputFile}"')
</syntaxhighlight >
</syntaxhighlight >
The command within <code>subprocess.run()</code> is the same as you would type into the command line. You can use Python's string formatting to insert variables.
The command within <code>subprocess.run()</code> is the same as you would type into the command line. You can use Python's [https://docs.python.org/3/tutorial/inputoutput.html#tut-f-strings string formatting] to insert variables.
==See Also==
==See Also==
* [[Video Codecs]]
* [[Video Codecs]]