I am trying to extract the image file from a RTSP stream url every second (could be every 1 min also) and overwrite this image file.
my below code works but it outputs to multiple image jpg files: img1.jpg, img2.jpg, img3.jpg...
ffmpeg -i rtsp://IP_ADDRESS/live.sdp -f image2 -r 1 img%01d.jpg
How to use ffmpeg or perhaps bash scripts in Linux to overwrite the same image file while continuously extract the image at a NOT high frequecy, say 1 min or 10 sec?
Following command line should work for you.
ffmpeg -i rtsp://IP_ADDRESS/live.sdp -f image2 -updatefirst 1 img.jpg
To elaborate a bit on the already accepted answer from pragnesh,
As stated in the ffmpeg documentation: ffmpeg command line options are specified as
ffmpeg [global_options] {[input_options] -i input_file} ... {[output_options] output_file} ...
So
ffmpeg -i rtsp://<rtsp_source_addr> -f image2 -update 1 img.jpg
Uses output option -f image2 , force output format to image2 format, as part of the muxer stage.
Note that in ffmpeg, if the output file name specifies an image format the image2 muxer will be used by default, so the command could be shortened to:
ffmpeg -i rtsp://<rtsp_source_addr> -update 1 img.jpg
The image2 format muxer expects a filename pattern, such as img%01d.jpg to produce a sequentially numbered series of files. If the update option is set to 1, the filename will be interpreted as just a filename, not a pattern, thereby overwriting the same file.
Using the -r , set frame rate, video option works, but generated me a whole lot of dropping frame messages which was bugging me.
Thanks to another answer on the same topic, I found the fps Video Filter to do a better job.
So my version of the working command is
ffmpeg -i rtsp://<rtsp_source_addr> -vf fps=fps=1/20 -update 1 img.jpg
For some reason still unkown to me the minimum framerate I can achieve from my feed is 1/20 or 0.05.
There also exists the video filter thumbnail, which selects an image from a series of frames but this is more processing intensive and therefore I would not recommend it.
Most of this and more I found on the FFMpeg Online Documentation
For those of you who use avconv it is very similar. They are after all forks of what was once a common library. The AVconv image2 documentation is found here.
avconv -i rtsp://<rtsp_source_addr> -vf fps=fps=1/20 -update 1 img.jpg
As Xianlin pointed out there may be a couple other interesting options to use:
-an : Disables audio recording.
-r < fps > : sets frame rate
leading to an alternate version :
avconv -i rtsp://<rtsp_source_addr> -r 1/20 -an -update 1 img.jpg
Hope it helps understand for possible further tweaking ;)
I couldn't get the option -update working to overwrite the .jpg. Doing some experiments resulted in a working solution (at least for me) with the option -y at the end (upper-case is not working). I also needed http:// instead of rstp:// for this camera.
ffmpeg -i http://xx:yy@192.168.1.xx:yyy/snapshot.cgi /tmp/Capture2.jpg -y
Grab a snapshot from an RTSP video stream every 10 seconds.
#!/bin/bash
#fetch-snapshots.sh
url='rtsp://IP_ADDRESS/live.sdp'
avconv -i $url -r 0.1 -vsync 1 -qscale 1 -f image2 images%09d.jpg
-r rate set frame rate to 0.1 frames a second (this equals to 1 frame every 10 seconds). Thanks to westonruter, see https://gist.github.com/westonruter/4508842
Furthermore have a look at FFMPEG: Extracting 20 images from a video of variable length
