How to stream a webcam feed in a Streamlit application

opencv_streamlit_webcam.md

Source

https://thiagoalves.ai/building-webcam-streaming-applications-with-streamlit-and-opencv/

How to run the application

streamlit run webcam_streamlit.py

requirements.txt

streamlit>=1.30
streamlit-webrtc>=0.47
opencv-python>=4.9
numpy>=1.26

webcam_streamlit.py

import cv2
import streamlit as st
from streamlit_webrtc import webrtc_streamer, VideoHTMLAttributes
import numpy as np
import av

st.title("OpenCV Filters on Video Stream")

filter = "none"


def transform(frame: av.VideoFrame):
    img = frame.to_ndarray(format="bgr24")

    if filter == "blur":
        img = cv2.GaussianBlur(img, (21, 21), 0)
    elif filter == "canny":
        img = cv2.cvtColor(cv2.Canny(img, 100, 200), cv2.COLOR_GRAY2BGR)
    elif filter == "grayscale":
        # We convert the image twice because the first conversion returns a 2D array.
        # the second conversion turns it back to a 3D array.
        img = cv2.cvtColor(cv2.cvtColor(img, cv2.COLOR_BGR2GRAY), cv2.COLOR_GRAY2BGR)
    elif filter == "sepia":
        kernel = np.array(
            [[0.272, 0.534, 0.131], [0.349, 0.686, 0.168], [0.393, 0.769, 0.189]]
        )
        img = cv2.transform(img, kernel)
    elif filter == "invert":
        img = cv2.bitwise_not(img)
    elif filter == "none":
        pass

    return av.VideoFrame.from_ndarray(img, format="bgr24")


col1, col2, col3, col4, col5, col6 = st.columns([1, 1, 1, 1, 1, 1])

with col1:
    if st.button("None"):
        filter = "none"
with col2:
    if st.button("Blur"):
        filter = "blur"
with col3:
    if st.button("Grayscale"):
        filter = "grayscale"
with col4:
    if st.button("Sepia"):
        filter = "sepia"
with col5:
    if st.button("Canny"):
        filter = "canny"
with col6:
    if st.button("Invert"):
        filter = "invert"


webrtc_streamer(
    key="streamer",
    video_frame_callback=transform,
    sendback_audio=False
    )