ffmpeg video reader - test

reader.py

import cv2
import numpy
import subprocess as sp

def get_video_info(video_file):
    
    cap = cv2.VideoCapture(video_file)
    framerate = cap.get(5) #frame rate
    # Get resolution of input video
    width  = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
    # Release VideoCapture - it was used just for getting video resolution
    cap.release()
    return width, height, framerate


FFMPEG_BIN = "ffmpeg" # on Linux ans Mac OS
buffer_size = 10**8

video_file = '/mnt/Downloads/MOT17-13-SDP-raw.mp4'

width, height, framerate = get_video_info(video_file)

print(f'[INFO] Video file: {video_file} {width}x{height} - {framerate} FPS')

command = [FFMPEG_BIN,
            '-i', video_file,
            '-f', 'image2pipe',
            '-pix_fmt', 'rgb24',
            '-vcodec', 'rawvideo', '-']

pipe = sp.Popen(command, stdout = sp.PIPE, bufsize=buffer_size)

# Read

fourcc = cv2.VideoWriter_fourcc(*'mp4v') 
video = cv2.VideoWriter('video.avi', fourcc, framerate, (width, height))
    
while True:
    # read 420*360*3 bytes (= 1 frame)
    raw_image = pipe.stdout.read(width*height*3)
    # transform the byte read into a numpy array
    image =  numpy.fromstring(raw_image, dtype='uint8')
    image = cv2.cvtColor(image.reshape((height,width,3)), cv2.COLOR_BGR2RGB)
    # Save image to output video stream
    video.write(image)
    # throw away the data in the pipe's buffer.
    pipe.stdout.flush()