[FFmpeg-user] Confusion about quality parameters

Ulf Zibis Ulf.Zibis at gmx.de
Tue Jun 25 21:31:47 EEST 2019

Am 25.06.19 um 20:16 schrieb Carl Eugen Hoyos:
> Am Di., 25. Juni 2019 um 20:11 Uhr schrieb Ulf Zibis <Ulf.Zibis at gmx.de>:
>> Am 25.06.19 um 15:04 schrieb Carl Eugen Hoyos:
>>> Am Di., 25. Juni 2019 um 14:15 Uhr schrieb Ulf Zibis <Ulf.Zibis at gmx.de>:
>>>> my input is a 1.5 minute mp4 video with 19.5 MB
>>>> When I use (with build from dev):
>>>>     ./ffmpeg in.mp4 -c:a copy out.mp4
>>> You do not specify an encoder here, mp4 defaults to x264.
>> If I understand Moritz and my output correct, it's quite contrary:
>> the dev build defaults to mpeg4.
> In this case (your forgot to provide the complete, uncut console
> output, so I had to guess) you have to provide either a constant
> quantiser or a bitrate for the command line to produce useful
> output (assuming state-of-the-art input as opposed to very low-res
> video).

Do you want to say, that ffmpeg by default always markably decreases the
bit rate and with that the quality, so a high res video is transcoded to
a low res video and a low res to a very very low res one?

Btw, sorry that I assumed you know what I meant with "build from dev".
But anyway I had post-posted the *complete* console output some minutes
later, Didn't you receive it?


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