Question

我想从youtube读取一个实时流来执行一些基本的CV事情，可能我们必须以某种方式删除youtube URL以将其转换为openCV可读的格式，如：？

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

有人做过吗？

Answer 1

我相信你现在已经知道了答案，但我会回答其他人搜索同一主题。你可以使用Pafy来做到这一点。首先你需要 import pafy

然后添加此

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

capture = cv2.VideoCapture()
capture.open(best.url)

那应该是它。

Answer 2

在 100-120 帧之后，@lee hannigan 的回答让我无法在 youtube 上直播。

我与 Pafy 制定了一种方法，只需抓取 x 帧数并将它们拼接在一起。不过，这最终导致将这些块拼接在一起的效果不佳，并给出了断断续续的结果。 Pafy 可能不是为直播而设计的，我找不到将帧无缝拼接在一起的方法。

最终有效的内容如下，根据guttentag_liu 在this post 上的回答略有修改。它需要更多的包，而且很长，但有效。因为文件是实时的，所以它需要分块，因此保存到一个临时文件中。您可能可以对每个块进行 openCV 工作，然后最后保存到文件中，而不是重新打开。

# 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)

如何使用openCV python阅读Youtube直播流？

2 个答案: