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• Unable to Play Video Stream on Flask-FFmpeg Media Server on Subsequent Requests

  12 juin 2024, par yternal

  Problem Description :

  


  I am trying to create a media server using Flask and FFmpeg. The server converts an RTSP stream to FLV format for playback in a web browser, and I am testing it using ffplay. The server starts successfully, and the data returned from the first request can be played using ffplay. However, when I interrupt the ffplay request and make it again, ffplay is unable to play the video and displays an "Invalid data found when processing input" error.

  


  I am using the following command to test with ffplay :

  


  ffplay http://127.0.0.1:8000/flv/0


  


  My current Flask code：

  


  import queue
import subprocess
import threading

from flask import Flask, Response, stream_with_context
from gevent import monkey
from gevent.pool import Pool
from gevent.pywsgi import WSGIServer
from geventwebsocket.handler import WebSocketHandler
from loguru import logger

monkey.patch_all()
app = Flask(__name__)

stream_queue = queue.Queue(maxsize=10000)


def update_stream():
    process = subprocess.Popen(
        ['ffmpeg', '-i', 'rtsp://192.168.1.168/0', '-f', 'flv', '-'],
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE
    )
    while True:
        data = process.stdout.read(4096)
        if not data:
            break
        if stream_queue.full():
            stream_queue.get()
        stream_queue.put(data)
        logger.debug(f"stream_queue size: {stream_queue.qsize()}")


@app.route('/flv/')
def flv_stream(stream_id):
    @stream_with_context
    def generate():

        while True:
            data = stream_queue.get()
            yield data

    return Response(generate(), mimetype='video/x-flv')


if __name__ == '__main__':
    HOST = "0.0.0.0"
    PORT = 8000

    threading.Thread(target=update_stream, daemon=True).start()

    logger.info(f"listen in: {HOST}:{PORT}")
    pool = Pool(10000)
    http_serve = WSGIServer((HOST, PORT), app, handler_class=WebSocketHandler, spawn=pool)
    http_serve.max_accept = 30000
    http_serve.serve_forever()


  


  The error message when attempting to play the stream again with ffplay is :

  


  http://127.0.0.1:8000/flv/0: Invalid data found when processing input


  


  I tried adding some parameters to FFmpeg, such as analyzeduration and probesize, but it had no effect.

  


• using FFMPEG commands , can i get the default values of any media file, like resolution, audio codec, video codec..etc

  30 novembre 2012, par rohit k.

  like for eg.
  if i enter the output extension '.avi' , i should get the default audio codec used , default video codec used , etc... Is there a command for this ?

• Media player get stuck in the middle of a buffered range on Chrome

  29 septembre 2019, par Feng Yu

  WHAT IS MY PROBLEM ?

  My website’s live streaming player use hls.js. From my server’s stat, there is many case where player get stuck in the middle of a buffered range.

  Here is my server raw stat log(removed some useless params) :

  tm=2019-09-27 12:04:41`bufferLevel=8.447303999999974`currentTime=158.4`buffered=[6.024,166.832]`readyState=4`ua=Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36 QBCore/3.53.1153.400 QQBrowser/9.0.2524.400 Tencent AppMarket/4.8 GameCenter

  currentTime is got by HTMLMediaElement.currentTime and buffered is got by HTMLMediaElement.buffered :

  currentTime=158.4
  
  buffered=[6.024,166.832]
  
  readyState=4

  From W3c :

  If HTMLMediaElement.buffered contains a TimeRange that includes the current playback position and enough data to ensure uninterrupted playback :

  1. Set the HTMLMediaElement.readyState attribute to HAVE_ENOUGH_DATA.
  2. Playback may resume at this point if it was previously suspended by a transition to HAVE_CURRENT_DATA.

  In this case, 613.3 is in the middle of [469.277,677.612], video should be progressing, but it is not.

  Hls.js will periodly check currentTime has progressed every 100ms. if currentTime has not progressed for 1000ms, then hls.js will trigger STALL event and I will send a stall stat to server.

  I cannot reproduce this problem on my side, it only appears on my server stat.

  WHAT I’VE TRIED

  shaka player has a module detect this case(https://www.ellealcatrase.eu/player2/docs/api/lib_media_stall_detector.js.html), Its comment shows that :

  Some platforms/browsers can get stuck in the middle of a
  buffered range (e.g. when seeking in a background tab). Detect when
  we get stuck so that the player can respond.

  but I cannot reproduce when my browser is in a background tab.