How to read Youtube live stream using openCV python?

Question

I want to read a live stream from youtube to perform some basic CV things, probably we have to somehow strip of the youtube URL to convert it in a format that might be readable by openCV like?:

cap = cv2.VideoCapture('https://www.youtube.com/watch?v=_9OBhtLA9Ig')

has anyone done it?

Answer 1

I am sure you already know the answer by now, but I will answer for others searching the same topic. You can do this by using Pafy (probably together with youtube_dl).

import pafy
import cv2

url = "https://www.youtube.com/watch?v=_9OBhtLA9Ig"
video = pafy.new(url)
best = video.getbest(preftype="mp4")

capture = cv2.VideoCapture(best.url)
while True:
    grabbed, frame = capture.read()
    # ...

And that should be it.

Answer 2

After 100-120 frames the answer from @lee hannigan was crashing on me for a live stream on youtube.

I worked out a method with Pafy to just grab x number of frames and splice them together. This ended up poorly stitching the chunks together though, and gave choppy results. Pafy may not be designed for live streams, I couldn't find a way to stitch the frames together seamlessly.

What worked in the end is below, slightly modified from guttentag_liu's answer on this post. It takes a few more packages, and is lengthy, but works. Because the file is live, it needs to be in chunks, hence saving to a temporary file. You could probably do your openCV work on each chunk, then save to a file in the end instead of re-opening.

# pip install urllib
# pip install m3u8
# pip install streamlink
from datetime import datetime, timedelta, timezone
import urllib
import m3u8
import streamlink
import cv2 #openCV

def get_stream(url):

    """
    Get upload chunk url
    input: youtube URL
    output: m3u8 object segment
    """
    #Try this line tries number of times, if it doesn't work, 
    # then show the exception on the last attempt
    # Credit, theherk, https://stackoverflow.com/questions/2083987/how-to-retry-after-exception
    tries = 10
    for i in range(tries):
    try:
        streams = streamlink.streams(url)
    except:
        if i < tries - 1: # i is zero indexed
            print(f"Attempt {i+1} of {tries}")
            time.sleep(0.1) #Wait half a second, avoid overload
            continue
        else:
            raise
    break

    stream_url = streams["best"] #Alternate, use '360p'

    m3u8_obj = m3u8.load(stream_url.args['url'])
    return m3u8_obj.segments[0] #Parsed stream


def dl_stream(url, filename, chunks):
    """
    Download each chunk to file
    input: url, filename, and number of chunks (int)
    output: saves file at filename location
    returns none.
    """
    pre_time_stamp = datetime(1, 1, 1, 0, 0, tzinfo=timezone.utc)

    
    #Repeat for each chunk
    #Needs to be in chunks because 
    #  1) it's live
    #  2) it won't let you leave the stream open forever
    i=1
    while i <= chunks:
       
        #Open stream
        stream_segment = get_stream(url)
    
        #Get current time on video
        cur_time_stamp = stream_segment.program_date_time
        #Only get next time step, wait if it's not new yet
        if cur_time_stamp <= pre_time_stamp:
            #Don't increment counter until we have a new chunk
            print("NO   pre: ",pre_time_stamp, "curr:",cur_time_stamp)
            time.sleep(0.5) #Wait half a sec
            pass
        else:
            print("YES: pre: ",pre_time_stamp, "curr:",cur_time_stamp)
            print(f'#{i} at time {cur_time_stamp}')
            #Open file for writing stream
            file = open(filename, 'ab+') #ab+ means keep adding to file
            #Write stream to file
            with urllib.request.urlopen(stream_segment.uri) as response:
                html = response.read()
                file.write(html)
            
            #Update time stamp
            pre_time_stamp = cur_time_stamp
            time.sleep(stream_segment.duration) #Wait duration time - 1

            i += 1 #only increment if we got a new chunk

    return None

def openCVProcessing(saved_video_file):
    '''View saved video with openCV
    Add your other steps here'''
    capture = cv2.VideoCapture(saved_video_file)

    while capture.isOpened():
        grabbed, frame = capture.read()  #read in single frame
        if grabbed == False:
            break

        #openCV processing goes here
        #
        
        cv2.imshow('frame',frame)  #Show the frame
        
        #Shown in a new window, To exit, push q on the keyboard
        if cv2.waitKey(20) & 0xFF == ord('q'):
            break

    capture.release()
    cv2.destroyAllWindows()  #close the windows automatically
                  
tempFile = "temp.ts"  #files are format ts, open cv can view them
videoURL = "https://www.youtube.com/watch?v=_9OBhtLA9Ig"

dl_stream(videoURL, tempFile, 3)
openCVProcessing(tempFile)