[FFmpeg-user] Output file size

[Rodolfo Medina]

Gyan <gyandoshi at gmail.com> writes:

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


Great.  Many thanks.

Rodolfo