[FFmpeg-trac] #7145(avfilter:new): Non-standard default orientation for lissajous in avectorscope

FFmpeg trac at avcodec.org
Wed Apr 18 02:52:27 EEST 2018


#7145: Non-standard default orientation for lissajous in avectorscope
-------------------------------------+-------------------------------------
             Reporter:  privatezero  |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  avfilter     |                  Version:  git-
             Keywords:               |  master
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------
 Summary of the bug: In the current git-master version of the avectorscope
 filter the {{{lissajous}}} mode is shifted 45 degrees in the wrong
 direction compared to standard audio lissajous scopes.

 With a mono source and the output set to {{{lissajous_xy}}}, the output
 conforms to what one would expect to see on an audio vectorscope (a
 diagonal line rising from left to right), however in the default
 {{{lissajous}}} mode, a mono signal registers as a horizontal line rather
 than a vertical line as is expected. This effectively means that in
 default settings the filter is always erroneously indicating that in-phase
 audio is perfectly out of phase.
 How to reproduce:
 {{{
 ffplay -f lavfi "sine=400,avectorscope=m=lissajous"
 ffmpeg version N-45798-gb3b3a3e
 built on 2018-04-17
 }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/7145>
FFmpeg <https://ffmpeg.org>
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