[FFmpeg-devel] Strange qmax behaviour with mpeg2

Michael Niedermayer michaelni at gmx.at
Tue Sep 11 17:59:35 CEST 2012

On Tue, Sep 11, 2012 at 12:02:14PM +0100, Joseph Artsimovich wrote:
> Hi,
> When encoding IMX 30 content (I-frame only mpeg2 at fixed bitrate) I
> noticed ffmpeg produces lower quality output than other encoders.
> Digging deeper, I found strange behaviour of qmax parameter with
> mpeg2video encoder that I can only explain away as a bug.
> Before explaining further, here is my command line:
> ffmpeg -i input.mov -vtag mx3p -vcodec mpeg2video -r 25 -pix_fmt
> yuv422p -minrate 30000k -maxrate 30000k -b:v 30000k -intra -flags
> +ildct+low_delay -dc 10 -intra_vlc 1 -non_linear_quant 1 -ps 1 -qmin
> 1 -qmax 8 -top 1 -bufsize 1200000 -rc_init_occupancy 1200000
> -rc_buf_aggressivity 0.25 -an out.mov

should be fixed
also you should add at least -lmin QP2LAMBDA

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The greatest way to live with honor in this world is to be what we pretend
to be. -- Socrates
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