app.py

import streamlit as st
import cv2
from PIL import Image

uploaded_video = st.file_uploader("Choose video", type=["mp4", "mov"])
frame_skip = 200 # display every 300 frames

if uploaded_video is not None: # run only when user uploads video
    vid = uploaded_video.name
    with open(vid, mode='wb') as f:
        f.write(uploaded_video.read()) # save video to disk

    st.markdown(f"""
    ### Files
    - {vid}
    """,
    unsafe_allow_html=True) # display file name

    vidcap = cv2.VideoCapture(vid) # load video from disk
    cur_frame = 0
    success = True

    while success:
        success, frame = vidcap.read() # get next frame from video
        if cur_frame % frame_skip == 0: # only analyze every n=300 frames
            print('frame: {}'.format(cur_frame)) 
            pil_img = Image.fromarray(frame) # convert opencv frame (with type()==numpy) into PIL Image
            st.image(pil_img,channels='BGR')
        cur_frame += 1