Opened 2 years ago

Closed 2 years ago

Last modified 2 years ago

#9388 closed defect (invalid)

showwaves filer, very dark output in p2p mode

Reported by: Michael Koch Owned by:
Priority: normal Component: avfilter
Version: git-master Keywords:
Cc: Blocked By:
Blocking: Reproduced by developer: no
Analyzed by developer: no


The "p2p" mode in the showwaves filter doesn't work correctly, if the "n" option is set to a value larger than 1. If the waveform has a large slope, the output becomes very dark, almost invisible. Can be reproduced as follows:

ffmpeg -f lavfi -i sine=100:d=0.2,volume=4 -lavfi showwaves=n=4:mode=p2p:s=2205x500 -frames 1 -y out.png

Change History (6)

comment:1 by Elon Musk, 2 years ago

Resolution: invalid
Status: newclosed

comment:2 by Elon Musk, 2 years ago

There is another option that draws every sample without blending.

comment:3 by Michael Koch, 2 years ago

"point" mode has the same problem (very dark), and "line" and "cline" modes are not what I want. I want to see the waveform as a line, like in an oscilloscope.

comment:4 by Michael Koch, 2 years ago

I did figure out that the "draw" option must be set to "full". But that really wasn't clear in the documentation. I suggest the following better documentation for the "draw" option:

Set the draw mode.
Available values are:
'scale' Use blending, that means the samples are drawn darker where the slope is larger. This is the default.
'full' Draw all samples with full intensity. This is useful for higher values of n.

comment:5 by Elon Musk, 2 years ago

send patch, otherwise such entries are not welcomed here.

comment:6 by Michael Koch, 2 years ago

Then it will stay as it is. GIT is too complicated.

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