[MPlayer-users] Lossless h264 Encoding

Guillaume POIRIER poirierg at gmail.com
Wed Oct 17 15:47:35 CEST 2007


On 10/17/07, Ognjen Bezanov <Ognjen at mailshack.com> wrote:
> Hello!
> I want to be able to encode to lossless h264 streams using
> mplayer/mencoder, but I have had no luck so far.
> I scoured the web and the mailing-lists and so far the only thing I have
> found is a thread (url:
> http://lists.mplayerhq.hu/pipermail/mencoder-users/2005-December/002293.html)
> specifying that setting qp_constant=0 should give me lossless encoding.
> All well and good, except that when I try setting that option I get the
> following error:
> "Option x264encopts: Unknown suboption qp_constant"
> Has mplayer changed the x264 options for lossless compression?

Yes, but apparently you didn't even care to read curren't manpage

              This selects the quantizer to use for P-frames.  I- and B-frames
              are offset from this value by ip_factor and  pb_factor,  respec-
              tively.  20-40 is a useful range.  Lower values result in better
              fidelity, but higher bitrates.  0 is lossless.  Note that  quan-
              tization  in  H.264  works  differently from MPEG-1/2/4: H.264's
              quantization parameter (QP) is on a logarithmic scale.  The map-
              ping  is  approximately H264QP = 12 + 6*log2(MPEGQP).  For exam-
              ple, MPEG at QP=2 is equivalent to H.264 at QP=18.


> How would
> I enable lossless h264 in mplayer now?

-x264encopts qp=0

A soldier will fight long and hard for a bit of colored ribbon.
 -- Napoleon Bonaparte

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