Sending FFmpeg output to HTTP, via Python's Flash

simplistic-ffmpeg-streaming.py

"""
Streaming FFmpeg to HTTP, via Python's Flask.
This is an incredibly simple example, which will yield issues due to inconsistant input and output rates.
If you're going to use this, VLC works okay as a client.
You really need to move FFmpeg into a separate thread, which should help stream audio more consistantly to the HTTP client.

Example by Anthony Eden (https://mediarealm.com.au)
"""

from flask import Flask
from flask import stream_with_context, request, Response
import subprocess
import time

app = Flask(__name__)

@app.route("/")
def hello():
    def generate():
        startTime = time.time()
        buffer = []
        sentBurst = False

        ffmpeg_command = ["ffmpeg", "-f", "avfoundation", "-i", ":2", "-acodec", "libmp3lame", "-ab", "32k", "-ac", "1", "-f", "mpeg", "pipe:stdout"]
        process = subprocess.Popen(ffmpeg_command, stdout = subprocess.PIPE, stderr = subprocess.STDOUT, bufsize = -1)

        while True:
            # Get some data from ffmpeg
            line = process.stdout.read(1024)

            # We buffer everything before outputting it
            buffer.append(line)

            # Minimum buffer time, 3 seconds
            if sentBurst is False and time.time() > startTime + 3 and len(buffer) > 0:
                sentBurst = True

                for i in range(0, len(buffer) - 2):
                    print "Send initial burst #", i
                    yield buffer.pop(0)

            elif time.time() > startTime + 3 and len(buffer) > 0:
                yield buffer.pop(0)

            process.poll()
            if isinstance(process.returncode, int):
                if process.returncode > 0:
                    print 'FFmpeg Error', p.returncode
                break

    return Response(stream_with_context(generate()), mimetype = "audio/mpeg")    

if __name__ == "__main__":
    app.run()

Another option to kill the process is to use the call_on_close decorator:

    response = Response(stream_with_context(generate()), mimetype = "audio/mpeg")

    @response.call_on_close
    def on_close():
        process.kill()
        
    return response

But you need to start the ffmpeg process outside of the generate closure e.g.

    ffmpeg_command = ["ffmpeg", "-f", "avfoundation", "-i", ":2", "-acodec", "libmp3lame", "-ab", "32k", "-ac", "1", "-f", "mpeg", "pipe:stdout"]
    process = subprocess.Popen(ffmpeg_command, stdout = subprocess.PIPE, stderr = subprocess.STDOUT, bufsize = -1)
    def generate():
        startTime = time.time()
        buffer = []