Hello together,

my rendered output file has sometimes artifacts. This happens irregular up to 10 times per minute and always in the lower area of the picture.

My source is 1080i50 h264 AVC from my camcorder. The complete workflow is interlaced, because destination is also 1080i50 bluray compliant material.
I do two pass rendering.

Here is a still picture (interlaced, played with ffplay):
http://www.pic-upload.de/view-13107696/artifacts.png.html

The artifacts lasts about 3 frames till picture is clear again.

Here my rendering profile:
AVOPTCON="f=mkv"
MLTOPT="-verbose -profile atsc_1080i_50"
AVOPTGEN="progress=1 threads=4 real_time=-1"
AVOPTVID="vcodec=libx264 preset=veryslow tune=film x264opts=bitrate=18000:vbv-maxrate=40000:vbv-bufsize=30000:level=4.1:keyint=25:slices=4:ref=4:colorprim=bt709:transfer=bt709:colormatrix=bt709:tff:bluray-compat:open-gop"
AVOPTAUDP1="acodec=ac3 ab=192k ar=48000"
AVOPTAUDP2="acodec=ac3 ab=192k ar=48000"
AVOPTP1="pass=1"
AVOPTP2="pass=2"

Please note: I do all rendering jobs via bash script direct with melt. Therefore there is a slightly different syntax.

I've played around a little bit and found out, that multithreading has an impact of amount of artifacts.
First I've compiled ffmpeg without libva, vda, vdpau but with no effect. If I have understood Dan correct in an earlier post, then vdpau is disabled by default within MLT and my ./configure output doesn't show any enabled support.

Second I tried out several threads=x settings. With threads=16 32 or 128 (just for fun and testing) I got a slightly increased amount of artifacts.
With threads=1 the video is absolutely clean! But rendering time is 16 hours for 38 minutes video!

My system: Intel Core i7 Mobility with 2 cores 4 threads. Normally my setting is threads=4.

Who has any idea?

My versions:
x264 stable git 4th Feb 2012 (0.120.2151)
ffmpeg n0.10 avformat 53.24.2 git 18th Feb
mlt 0.7.8 released
kdenlive 0.8.2-273 18th Feb
Open Suse 12.1 64 Bit

BluRay compliant means, that the output mkv file is the source for multiAVCHD to become finally compliant muxed.

Christian

solved.
with current x264 master instead of last stable, the picture is clean!
Christian