How to access uploaded video in streamlit by open cv?

Using Streamlit
8

Something like this should work. The key is defining st.empty() outside of the loop, then writing to the object from inside the loop:

import streamlit as st
import cv2 as cv
import tempfile

f = st.file_uploader("Upload file")

tfile = tempfile.NamedTemporaryFile(delete=False) 
tfile.write(f.read())


vf = cv.VideoCapture(tfile.name)

stframe = st.empty()

while vf.isOpened():
    ret, frame = vf.read()
    # if frame is read correctly ret is True
    if not ret:
        print("Can't receive frame (stream end?). Exiting ...")
        break
    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
    stframe.image(gray)
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