Capture webcam using ffmpeg-python library

Question

Hi I'm attempting to capture a webcam stream with python using the ffmpeg-python wrapper library ( https://github.com/kkroening/ffmpeg-python ) I have a working ffmpeg command which is:

ffmpeg -f v4l2 -video_size 352x288 -i /dev/video0 -vf "drawtext='fontfile=fonts/FreeSerif.ttf: text=%{pts} : \
x=(w-tw)/2: y=h-(2*lh): fontcolor=white: box=1: boxcolor=0x00000000@1'" -an -y -t 15 videotests/out_localtime8.mp4

This captures 15s of video in resolution 352x288, and writes a timestamp in the bottom centre of the video.

To play with the ffmpeg-python library, I'm simply attempting to only get the drawtext filter working, here is my script:

#!/usr/bin/env python

import ffmpeg
stream = ffmpeg.input('videotests/example.mov')
stream = ffmpeg.filter_(stream,'drawtext',("fontfile=fonts/FreeSerif.ttf:text=%{pts}"))
stream = ffmpeg.output(stream, 'videotests/output4.mp4')
ffmpeg.run(stream)

The error is

[Parsed_drawtext_0 @ 0x561f59d494e0] Either text, a valid file or a timecode must be provided
[AVFilterGraph @ 0x561f59d39080] Error initializing filter 'drawtext' with args 'fontfile\\\=fonts/FreeSerif.ttf\\\:text\\\=%{pts}'
Error initializing complex filters.
Invalid argument

The above appears to at least reach ffmpeg but the format of the arguments is incorrect, how to correct them?

Alternatively, when I attempting to split the argument to just pass one of them, I get a different error, as follows:

stream = ffmpeg.filter_(stream,'drawtext',('text=%{pts}'))

Error is

subprocess.CalledProcessError: Command '['ffmpeg', '-i', 'videotests/example.mov', '-filter_complex', "[0]drawtext=(\\\\\\\\\\\\\\'text\\\\\\\\\\\\=%{pts}\\\\\\\\\\\\\\'\\,)[s0]", '-map', '[s0]', 'videotests/output4.mp4']' returned non-zero exit status 1.

How come there are so many backslashes? Any advice on how to proceed please.

Thank you

Answer 1

I worked out the correct syntax eventually. Here is a working example

#!/usr/bin/env python

import ffmpeg
stream = ffmpeg.input('videotests/example.mov')
stream = ffmpeg.filter_(stream,'drawtext',fontfile="fonts/hack/Hack-Regular.ttf",text="%{pts}",box='1', boxcolor='0x00000000@1', fontcolor='white')
stream = ffmpeg.output(stream, 'videotests/output6.mp4')
ffmpeg.run(stream)

The syntax is

ffmpeg.filter_(<video stream name>,'<filter name>',filter_parameter_name='value',<filter_parameter_name>=value)

Where necessary use quotes for the filter_parameter_name values.

Hope this helps someone.

Answer 2

step 1: set environment variable for ffmpeg.

step 2: below code will help to to capture image as well as video using ffmpeg in python along with its current date and time.

 import subprocess from datetime import datetime import time class Webcam: def Image(self): try: user = int(input("How many Images to be captured:")) except ValueError: print("\\nPlease only use integers") for i in range (user): subprocess.call("ffmpeg -f vfwcap -vstats_file c:/test/log"+ datetime.now().strftime("_%Y%m%d_%H%M%S") +".txt -t 10 -r 25 -i 0 c:/test/sample"+ datetime.now().strftime("_%Y%m%d_%H%M%S") +".jpg") time.sleep(3) def Video(self): try: user = int(input("How many videos to be captured:")) except ValueError: print("\\nPlease only use integers") for i in range (user): subprocess.call("ffmpeg -f vfwcap -vstats_file c:/test/log"+ datetime.now().strftime("_%Y%m%d_%H%M%S") +".txt -t 10 -r 25 -i 0 c:/test/sample"+ datetime.now().strftime("_%Y%m%d_%H%M%S") +".avi") time.sleep(5) Web=Webcam() print ("press 1 to capture image") print ("Press 2 to capture video") choose = int(input("Enter choice:")) if choose == 1: Web.Image() elif choose == 2: Web.Video() else: print ("wrong choose") 

import subprocess : Is use to call FFMPEG command.

subprocess is the in-build module provided by python