[FFmpeg-user] inconsistent ffmpeg results when running same command on different machines

[Frank Schwieterman]

  Thanks for the insight Moritz.  I suspect that the libx264 version is
determined by whoever puts together the build, and so picking up windows
and mac builds there isn't a straightforward way to keep those in sync.
 Getting a binary match is not critical, so this is ok.
  One concern though is that the result lengths are different.  I am trying
to extract a clip of a specific length, which is going to be concatenated
for a loop effect.  It is important that the concatenated portion is a
specific time duration because the loop establishes a musical tempo.
  The command I run should extract video from time 0.1 to 0.2, so I'd
expect the output result to be 0.1 seconds long.  From the output, it says
it is 0.11s or 0.12s instead (I see "frame= 3 fps=0.0 q=-1.0 Lsize= 133kB
time=00:00:00.12 bitrate=8851.7kbits/s dup=6 drop=0" in one). I suppose
0.02 error on the duration is reasonable, if the error stays the same as
the clip is extended. Would you know if I could expect a similar fixed-size
error regardless of the duration of the extracted clip?

On Sun, Aug 11, 2013 at 3:04 PM, Moritz Barsnick <barsnick at gmx.net> wrote:

> On Sun, Aug 11, 2013 at 14:51:49 -0700, Frank Schwieterman wrote:
> > I suspect the ffmpeg configuration is different...
>
> The ffmpeg output (at the very top) will hint you towards that.
>
> > Is it possible to configure things such that I'd get the same result
> > from both machines?
>
> I guess if the identical versions of ffmpeg and all used libraries are
> identical (same versions, same configuration, not necessarily same
> compilers though), it should work.
>
> Your ffmpeg base code seems in sync (judging from the reported versions
> of the libav* libraries).
>
> But since these two differ version-wise:
> > [libx264 @ 0x7ff461908e00] 264 - core 125 - H.264/MPEG-4 AVC codec -
> Copyleft 2003-2012 - http://www.videolan.org/x264.html - options: cabac=1
> ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00
> mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11
> fast_pskip=1 chroma_qp_offset=-2 threads=6 lookahead_threads=1
> sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0
> constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1
> weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40
> intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0
> qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
> > [libx264 @ 0000000002246da0] 264 - core 130 r2274 c832fe9 - H.264/MPEG-4
> AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html -
> options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1
> psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1
> cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=6
> lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0
> bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1
> b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25
> scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0
> qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
> you can suspect that they won't create bitwise identical output in the
> payload.
>
> Moritz
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