[FFmpeg-user] Output file size

[Gyan]

On Mon, May 29, 2017 at 9:29 PM, Rodolfo Medina <rodolfo.medina at gmail.com>
wrote:

> Hi all.
>
> I'm adding id3 tags to a 208M mp3 file, with:
>
>  $ ffmpeg -i input.mp3 -metadata artist="Caterina Pontrandolfo Quartett"
> -metadata album="concerto di Fonte Avellana" -metadata genre="popular"
> -metadata composer="tradizione lucana" output.mp3
>
> .  Now, the output.mp3 is only 83M.  Why this?  Does it mean a quality
> loss?
> How can I avoid it?  How can I have output.mp3 the same size as input.mp3?
>

Unless specified otherwise, ffmpeg will transcode streams. You have to add

-c copy

 to force stream copy (if the output format supports it). So,

$ ffmpeg -i input.mp3 -c copy -metadata artist="Caterina Pontrandolfo
Quartett" -metadata album="concerto di Fonte Avellana" -metadata
genre="popular" -metadata composer="tradizione lucana" output.mp3