The transition_stream function uses the YouTube API to authorize and bind a stream to a broadcast, then starts a subprocess to write images to an FFmpeg stream, waiting indefinitely until interrupted. The code includes unused sections for creating stream data and transitioning the broadcast status to 'live', which are likely part of a larger script or implementation.

Run example

npm run import -- "transition live stream"

transition live stream

import time
import subprocess
from googleapiclient.discovery import build
import_notebook("bind youtube stream",
"globals("))
import_notebook("list live stream",
"globals("))


def transition_stream():

    credentials = youtube_authorize()

    # Build the YouTube API client
    youtube = build("youtube", "v3", credentials=credentials)

    stream, broadcast_id = bind_stream_to_broadcast()

    args = ["python", "-c", "__import__('Core').run()", "python write images to ffmpeg stream", "--streamName=" + stream['cdn']['ingestionInfo']['streamName']]
    process = subprocess.Popen(args)


    # create 10 seconds of stream data before going live
    #time.sleep(10)

    # Set the broadcast status to 'live'
    #request = youtube.liveBroadcasts().transition(
    #    broadcastStatus="live",
    #    id=broadcast_id,
    #    part="id,status"
    #)
    #response = request.execute()
    #print(response)


    try:
        while True:
            time.sleep(1)
    except KeyboardInterrupt:
        print("\nCTRL+C detected. Exiting...")

    os.killpg(os.getpgid(process.pid), signal.SIGTERM) 


__all__ = {
    "transition_stream": transition_stream
}

```markdown
# Transition Stream
====================

A function to initiate a YouTube Live stream using the Google API and system commands.

### Dependences
---------------

*   `googleapiclient`
*   `subprocess`
*   `os`
*   `signal`

### Functions
-------------

#### `transition_stream`

Transition a YouTube Live stream.

```python
import os
import signal
import subprocess
import time
from googleapiclient.discovery import build
from google.oauth2.credentials import Credentials
from googleapiclient.errors import HttpError

def youtube_authorize() -> Credentials:
    """
    Authenticate with Google using a credentials file.
    
    TODO: Implement a more secure authentication method.
    """
    # For security reasons, we recommend to use a more secure authentication method.
    # This is a placeholder.
    return Credentials(None)

def bind_stream_to_broadcast() -> tuple:
    """
    Bind a stream to a broadcast.
    
    Returns:
        tuple: A tuple containing the stream and broadcast ID.
    """
    # For security reasons, we recommend to use a more secure authentication method.
    # This is a placeholder.
    return {"cdn": {"ingestionInfo": {"streamName": "stream-name"}}}, "broadcast-id"

def runffmpeg(stream_name: str) -> None:
    """
    Run the ffmpeg process.
    
    Args:
        stream_name (str): The name of the stream.
    """
    args = ["python", "-c", "__import__('Core').run()", "python write images to ffmpeg stream", 
            "--streamName=" + stream_name]
    process = subprocess.Popen(args)
    return process

def transition_stream():
    """
    Transition a YouTube Live stream.
    """
    # Authenticate with Google
    credentials = youtube_authorize()
    
    # Build the YouTube API client
    youtube = build("youtube", "v3", credentials=credentials)
    
    # Bind the stream to a broadcast
    stream, broadcast_id = bind_stream_to_broadcast()
    
    # Run the ffmpeg process
    process = runffmpeg(stream["cdn"]["ingestionInfo"]["streamName"])
    
    # Create 10 seconds of stream data before going live
    # We can remove this line if we don't need to generate stream data.
    # time.sleep(10)
    
    try:
        while True:
            time.sleep(1)
            # Check if the stream is still running
            if not process.poll():
                break
    except KeyboardInterrupt:
        print("\nCTRL+C detected. Exiting...")
    
    # Terminate the ffmpeg process
    os.killpg(os.getpgid(process.pid), signal.SIGTERM)

__all__ = {"transition_stream": transition_stream}
```

Code Breakdown

Import Statements

The code imports the following modules:

• time: for time-related functions
• subprocess: for executing external processes
• googleapiclient.discovery: for building the YouTube API client
• import_notebook: used to import functions from Jupyter notebooks (not a standard Python module)
• os and signal: for process management (not explicitly imported, but used later)

transition_stream Function

The transition_stream function performs the following tasks:

1. Authorizes with the YouTube API using youtube_authorize function (not shown in the code snippet).
2. Builds the YouTube API client using build function from googleapiclient.
3. Binds a stream to a broadcast using bind_stream_to_broadcast function (not shown in the code snippet).
4. Starts a subprocess to run a Python script that writes images to an FFmpeg stream.
5. Waits indefinitely (with a 1-second sleep) until interrupted by a KeyboardInterrupt.
6. Terminates the subprocess using os.killpg and signal.SIGTERM.

Unused Code

The code snippet includes commented-out sections that create 10 seconds of stream data before going live and transition the broadcast status to 'live'. These sections are not executed in the provided code.

Special Note

The import_notebook function and the bind_stream_to_broadcast function are not standard Python functions and are likely custom implementations. The youtube_authorize function is also not shown in the code snippet. These functions are not explained in the provided code, and their implementation is assumed to be elsewhere.