[FFmpeg-user] sample DVCPRO50 file showing white-line-in-top-MB-row problem

Sal Kennedy mugfunky at gmail.com
Wed Sep 18 04:11:51 CEST 2013

I posted yesterday but made a mess of subscribing to this list, hence i
cannot easily reply to it.  here's the link to the archived posting though:

i've attempted to upload a sample to upload.ffmpeg.org/incoming, but
apparently 1 connection is too many.

here's a link to the file on datafilehost (i saw it linked to in another
thread, suggested by a member, so i hope it's fine to use it):


below is the content of the little text file i was going to pop on
/incoming.  it contains steps to reproduce and the origin of the file in
question.  i hope this is enough.

log output can be provided, but as this is a universal libavcodec issue it
seems that it would not be helpful - simply playing back the sample in VLC
will reproduce, or decoding in ffmpeg, libav, ffms2, etc.  decoding in
premiere or final cut does not display this behaviour.



i seem to have a problem with DVCPRO50 files.  these don't come by very
often, but one of our
licensors has decided to save on tapes and send us files straight off their
big shiny
quantel media server thing.  this means MXF DV50 for SD, and MXF MPEG-IMX
for HD.

i've been using ffmpeg to transcode these files into prores mezzanines for
easier handling
(and a space saving at no appreciable quality loss) - i can re-map the
audio channels and keep
only what's needed that way, as the supplied files can be quite

however, i've noticed what appear to be decoding artefacts.  only the top
row of blocks are
affected as far as i can see.  white lines appear whenever the block is
over a certain
brightness.  i can't give any more information than that as i've been
unable to reproduce this
with synthetic signals so far, so maybe complexity is also a factor.

when i use premiere to decode, the lines are not present.

the sample file provided is clipped out of an mxf master file with the
following command:

"ffmpeg.exe" -i "source.MXF" -an -c:v copy -ss 66.24 -to 67.74

i can provide a bigger file, but the bug report guidelines say <10meg...
 the bug is apparent though - look at the sun.

to reproduce the decoding bug, one simply has to decode the sample file to
anything.  here's what i normally use:

%FFMPEG% -i "source.any" -c:a pcm_s16le -c:v prores -profile:v 2

ffmpeg was built from git yesterday, but this problem has been apparent for
much longer it seems.

all libavcodec based apps have this issue - libav, ffms2, VLC player, etc

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