Bash – ffmpeg capture current frame and overwrite the image output file

bashffmpeg

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?

Best Answer

Following command line should work for you.

ffmpeg -i rtsp://IP_ADDRESS/live.sdp -f image2 -updatefirst 1 img.jpg

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Linux – How to redirect output to a file and stdout

The command you want is named tee:

foo | tee output.file

For example, if you only care about stdout:

ls -a | tee output.file

If you want to include stderr, do:

program [arguments...] 2>&1 | tee outfile

2>&1 redirects channel 2 (stderr/standard error) into channel 1 (stdout/standard output), such that both is written as stdout. It is also directed to the given output file as of the tee command.

Furthermore, if you want to append to the log file, use tee -a as:

program [arguments...] 2>&1 | tee -a outfile

Bash – Pipe output and capture exit status in Bash

There is an internal Bash variable called $PIPESTATUS; it’s an array that holds the exit status of each command in your last foreground pipeline of commands.

<command> | tee out.txt ; test ${PIPESTATUS[0]} -eq 0

Or another alternative which also works with other shells (like zsh) would be to enable pipefail:

set -o pipefail
...

The first option does not work with zsh due to a little bit different syntax.

Best Answer

Related Solutions

Linux – How to redirect output to a file and stdout

Bash – Pipe output and capture exit status in Bash

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