On 13-05-2019 12:36 AM, Thomas Seilund wrote:
On 12/05/2019 19.25, Gyan wrote:
On 12-05-2019 10:43 PM, Thomas Seilund wrote:
Hi All
I capture video stream from webcam and show video on screen.
The same stream goes through the 'metadata' multimedia filter as
shown below:
ffmpeg -y -f v4l2 -input_format mjpeg -s hd480 -r 30 -i /dev/video2
-filter_complex
"[0:0]select='gte(scene,0)',metadata=print:file='movement.txt',null[X]"
-map '[X]' -pix_fmt yuv420p -f xv Title
The text file 'movement.txt' gets information about each frame. BUT
data is written to text file 'movement.txt' buffered. Is there any
way to write data to text file 'movement.txt' as each frame is
processed?
Not at present. The file protocol will buffer up to 256 kB and then
write out. There is an option to write immediately but it isn't
applied to the metadata filter as its I/O context is isolated. I plan
to patch that soon-ish.
Gyan
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Thanks Gyan.
Is there another way to get the metadata, ie. lavfi.scene_score, as
the frame is processed?
Basically, I want to take some action when there is motion in the video!
If you increase the log level to debug or higher, you should see lines
of the form
[Parsed_select_0 @ 00000000006feb80] n:1524.000000 pts:780288.000000
t:60.960000 key:0 interlace_type:P pict_type:B scene:0.000987 ->
select:1.000000 select_out:0
The "scene:" value is what you want.
To capture this, you either redirect stderr to a file or add -report to
your command. The latter will generate a text file in PWD.
Gyan
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