[FFmpeg-user] Large Sized output files recieved while encoding the audio

Carl Zwanzig cpz at tuunq.com
Wed Apr 20 19:51:45 EEST 2022

On 4/20/2022 9:31 AM, Shubham Tiwari wrote:

> My use case is redaction of audio. To achieve this, our backend adds the
> filter to mute the audio in the ffmpeg command and then executes on audio
> files. 

What are those commands? The original email only shows basic file conversion.

>  When we use the extension of the output
> audio file as mp3, then the time taken is high. When we use the original
> extension (wav) in the output audio file, then the file size is high (for
> some cases, the size goes upto 250mb+).

To expand on what Ferdi said- on input the file extension is only used to 
make a guess about the format; on output it's used to select that format 
unless told otherwise. So if the output file is called file.wav, ffmpeg is 
going to write an uncompressed wav; if it's file.mp3, ffmpeg will write an 
mp3 file using default parameters. All of that can be overridden using 
command line parameters.

Please read parts 1-7 of the doc at https://ffmpeg.org/ffmpeg-all.html to 
see how the parameters & options behave.

> Do you know the reason why reducing the quality even further takes
> longer?
That's decoding the compressed data into raw/uncompressed date, the 
re-compressing/encoding; more steps, more work.

Also, please read https://ffmpeg.org/mailing-list-faq.html



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