On Tue, Mar 15, 2011 at 11:21:28AM -0700, Stacey Campbell wrote:
> Hi,
> 
> I've pulled the latest git ffmpeg and schroedinger and hacked/configured
> ffmpeg's libschroedinger_encode_init to use
> SCHRO_ENCODER_RATE_CONTROL_LOW_DELAY.  I processed a sequence of
> 1920x1080 HD RGB24 frames one at a time as YUV422 (YUV444 coredumps)
> and see flickering diagonal bands of noise moving over the frames.
> 
> I then did roughly the same experiment with git dirac-research -- no low
> delay processing(?), and YUV444, which is what I actually want -- and
> the noise bands are not there for the same compression ratio.

Low delay works here, with both 4:2:2 and 4:4:4, using GStreamer:

  gst-launch videotestsrc ! \
    video/x-raw-yuv,format=\(fourcc\)AYUV,width=1920,height=1080 ! \
    schroenc rate-control=low_delay force-profile=vc2_low_delay \
      bitrate=200000000 intra-wavelet=1 ! \
    schrodec ! colorspace ! xvimagesink sync=false

Possible reasons it's not working for you:  Orc is generating bad code
(sometimes happens, although pretty infrequently these days).  You
can test this by running the testsuite (make check), and/or running
your code using ORC_CODE=backup in the environment.

Another possible reason, if you're seeing diagonal "comets", is that
the transform-depth is changed away from the default.  This is a bad
idea.

As a side note, low delay profile is very sensitive to the values of
horiz-slices and vert-slices.  These should be factors of (width/16)
and (height/8), which pretty much means 120 and 135.



David



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