New Component: streamlit-webrtc, a new way to deal with real-time media streams

Custom Components streamlit-webrtc
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23

Thank you!

For you question, I think the answer is yes.
You can access the frame arrays in the transform() method of your VideoTransformer.
Please check the code below. I hope it meets your needs.

Note that these snapshots are taken on the server-side, not on the frontend,
then if there is a network delay, there will be a delay in when the photos are taken.

import threading
from typing import Union

import av
import numpy as np
import streamlit as st

from streamlit_webrtc import VideoTransformerBase, webrtc_streamer


def main():
    class VideoTransformer(VideoTransformerBase):
        frame_lock: threading.Lock  # `transform()` is running in another thread, then a lock object is used here for thread-safety.
        in_image: Union[np.ndarray, None]
        out_image: Union[np.ndarray, None]

        def __init__(self) -> None:
            self.frame_lock = threading.Lock()
            self.in_image = None
            self.out_image = None

        def transform(self, frame: av.VideoFrame) -> np.ndarray:
            in_image = frame.to_ndarray(format="bgr24")

            out_image = in_image[:, ::-1, :]  # Simple flipping for example.

            with self.frame_lock:
                self.in_image = in_image
                self.out_image = out_image

            return out_image

    ctx = webrtc_streamer(key="snapshot", video_transformer_factory=VideoTransformer)

    if ctx.video_transformer:
        if st.button("Snapshot"):
            with ctx.video_transformer.frame_lock:
                in_image = ctx.video_transformer.in_image
                out_image = ctx.video_transformer.out_image

            if in_image is not None and out_image is not None:
                st.write("Input image:")
                st.image(in_image, channels="BGR")
                st.write("Output image:")
                st.image(out_image, channels="BGR")
            else:
                st.warning("No frames available yet.")


if __name__ == "__main__":
    main()
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