[FFmpeg-user] convert a video to some format and than bring it back exactly the same

[Moritz Barsnick]

Hi Julien,

On Thu, Apr 29, 2021 at 04:17:20 +0200, Julien Dotsev wrote:
> I see there is a difference in the file size. The first avi is *1462KB* and
> after the reconversion is *1474KB*.
>
> My question is is there a way to take a video file from a client, convert
> it to some readable by  HTML <video> tag format and after I finish using it
> be able to bring to the client the original file, exactly the same.

No, there is no such way. Every video operation with ffmpeg involves
demuxing and muxing. And every muxer - so also ffmpeg's - has more or
less subtle differences. ffmpeg may be less efficient (therefore the
larger size), have other presents, and so on. Furthermore, your first
operation may also lose metadata or data streams, which your second
operation cannot recover.

Cheers,
Moritz