app.py

import streamlit as st
import cv2
import time
import threading
import os
from streamlit_autorefresh import st_autorefresh

# Initialize session state for broadcasting if not already set
if "broadcasting" not in st.session_state:
    st.session_state.broadcasting = False
if "broadcaster_thread" not in st.session_state:
    st.session_state.broadcaster_thread = None

def broadcast_loop(camera_index):
    """
    Capture 3-second segments from the selected camera and write them to 'latest.mp4'.
    This loop runs in a background thread while st.session_state.broadcasting is True.
    """
    cap = cv2.VideoCapture(int(camera_index))
    if not cap.isOpened():
        st.error("Could not open camera.")
        return

    # Try to determine FPS; default to 20 if not available.
    fps = cap.get(cv2.CAP_PROP_FPS)
    if fps is None or fps < 1:
        fps = 20

    width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
    height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

    while st.session_state.broadcasting:
        # Open a VideoWriter to record a 3-second segment.
        fourcc = cv2.VideoWriter_fourcc(*'mp4v')
        out = cv2.VideoWriter("latest.mp4", fourcc, fps, (width, height))
        segment_start = time.time()

        while time.time() - segment_start < 3 and st.session_state.broadcasting:
            ret, frame = cap.read()
            if not ret:
                break
            out.write(frame)
            time.sleep(1.0 / fps)
        out.release()  # Close the file so that it can be served.
    cap.release()

def start_broadcast(password, camera_index):
    """
    Start broadcasting if the correct password is entered.
    """
    if password != "test123":
        return "Incorrect password! Broadcast not started."
    if not st.session_state.broadcasting:
        st.session_state.broadcasting = True
        thread = threading.Thread(target=broadcast_loop, args=(camera_index,), daemon=True)
        st.session_state.broadcaster_thread = thread
        thread.start()
        return "Broadcasting started."
    else:
        return "Already broadcasting."

def stop_broadcast():
    """
    Stop broadcasting by setting the broadcasting flag to False.
    """
    if st.session_state.broadcasting:
        st.session_state.broadcasting = False
        return "Broadcast stopped."
    else:
        return "Not broadcasting."

def get_latest_video_path():
    """
    Return the path to the latest video if it exists.
    """
    return "latest.mp4" if os.path.exists("latest.mp4") else None

# Set page configuration
st.set_page_config(page_title="Temporary File‑Based Live Stream", layout="wide")
st.title("Temporary File‑Based Live Stream with Streamlit")

# Create two tabs: one for broadcasting and one for viewing.
tabs = st.tabs(["Broadcast", "View"])

with tabs[0]:
    st.header("Broadcasting Controls")
    password_input = st.text_input("Enter broadcast password:", type="password")
    camera_index_input = st.number_input("Camera Index", min_value=0, value=0, step=1)
    col1, col2 = st.columns(2)
    with col1:
        if st.button("Start Broadcasting"):
            status = start_broadcast(password_input, camera_index_input)
            st.info(status)
    with col2:
        if st.button("Stop Broadcasting"):
            status = stop_broadcast()
            st.info(status)

with tabs[1]:
    st.header("Live View")
    video_path = get_latest_video_path()
    if video_path:
        # Automatically refresh the app every 3 seconds to load the latest file.
        st_autorefresh(interval=3000, key="video_autorefresh")
        st.video(video_path)
    else:
        st.write("No broadcast available yet.")