[FFmpeg-devel] Strange qmax behaviour with mpeg2

[Reimar Döffinger]

On 11 Sep 2012, at 17:59, Michael Niedermayer <michaelni at gmx.at> wrote:
> 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

Ah. Sorry for all my wrong assumptions I posted...