streaming m3u8 file with opencv

Question

I am trying to capture a live stream from a GoPro using cv2 in python with the following code:

VIDEO_URL = "http://10.5.5.9:8080/live/amba.m3u8"
cam = cv2.VideoCapture(VIDEO_URL)
cv2.namedWindow("GoPro",cv2.CV_WINDOW_AUTOSIZE)
while True:
    f, im = cam.read()
    cv2.imshow("GoPro",im)
    if cv2.waitKey(5) == 27:
        break
cam.release()
cv2.destroyAllWindows()

but receive the following errors:

WARNING: Couldn't read movie file http://10.5.5.9:8080/live/amba.m3u8
OpenCV Error: Assertion failed (size.width>0 && size.height>0) in imshow, file     /tmp/opencv-MRl1/opencv-2.4.7.1/modules/highgui/src/window.cpp, line 261
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "gopro_simple.py", line 167, in live_stream
    cv2.imshow("GoPro",im)
cv2.error: /tmp/opencv-MRl1/opencv-2.4.7.1/modules/highgui/src/window.cpp:261: error: (-215) size.width>0 && size.height>0 in function imshow

The stream works in vlc, and the code works with a webcam, so it looks like the problem is that opencv doesn't like the .m3u8 format. Any ideas / suggestions of how to fix this would be greatly appreciated. Thanks.

Answer 1

Found a solution which calls ffmpeg here - works great (with a couple of small alterations to the ffmpeg options):

VIDEO_URL = WEBURL + "live/amba.m3u8"

cv2.namedWindow("GoPro",cv2.CV_WINDOW_AUTOSIZE)

pipe = sp.Popen([ FFMPEG_BIN, "-i", VIDEO_URL,
           "-loglevel", "quiet", # no text output
           "-an",   # disable audio
           "-f", "image2pipe",
           "-pix_fmt", "bgr24",
           "-vcodec", "rawvideo", "-"],
           stdin = sp.PIPE, stdout = sp.PIPE)
while True:
    raw_image = pipe.stdout.read(432*240*3) # read 432*240*3 bytes (= 1 frame)
    image =  numpy.fromstring(raw_image, dtype='uint8').reshape((240,432,3))
    cv2.imshow("GoPro",image)
    if cv2.waitKey(5) == 27:
        break
cv2.destroyAllWindows()

Still tinkering with the code so any suggestions welcome.