[FFmpeg-user] Problem with astats and adrawgraph
astroelectronic at t-online.de
Tue Nov 26 14:46:34 EET 2019
>> Thanks for your suggestion. Adding -r 25 does indeed solve the problem.
>> Although I don't understand why it is required. The input framerate is
>> 25 and it's detected correctly when I use the simpler filter chain.
> Ah, I know why this happens, you need to use settb=1/FPS filter after vstack.
> This happens because adrawgraph filter it order to not drop output
> frames need to have same timebase as input audio. Otherwise you would
> get different metadata values.
> Also note that your FPS in this case is 48000/1024. ~= 46.xxx
48000 is the audio sample rate, but where does the 1024 come from?
I have a new example with testsrc2 and anoisesrc. There is no input file
required for reproducing.
There are two graphs: The first one uses signalstats and drawgraph, and
the second one uses astats and adrawgraph. The problem is that the two
graphs don't advance with the same speed in X direction. Do you have an
idea how to make them synchrone?The video width is the same in both
cases, otherwise vstack wouldn't work.
The speed of drawgraph is correct, 1 pixel per frame. The speed of
adrawgraph is too fast.
Other question: reset=1 in astats means that the calculation result is
reset after each frame. But how does the filter know when a frame ends,
if the input of this filter is only an audio signal?
c://ffmpeg/ffmpeg -f lavfi -i testsrc2=size=hd1080:duration=10:rate=25
-f lavfi -i anoisesrc=d=10:c=pink:r=48000 -lavfi
-r 25 -y test.mp4
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