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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.

  


• avcodec/mips/aaccoder_mips : Remove MIPS-specific aaccoder

  15 mars 2024, par Andreas Rheinhardt

  avcodec/mips/aaccoder_mips : Remove MIPS-specific aaccoder
  ff_aac_coder_init_mips() modifies a static const structure of
  
  function pointers. This will crash if the binary uses relro
  
  and is a data race in any case.
  Furthermore it points to a maintainability issue : The
  
  AACCoefficientsEncoder structures have been constified
  
  in commit fd9212f2edfe9b107c3c08ba2df5fd2cba5ab9e3,
  
  a Libav commit merged in 318778de9ebec276cb9dfc65509231ca56590d13.
  
  Libav did not have the MIPS-specific AAC code and so this was
  
  fine for them ; yet FFmpeg had them, but this was not recognized.
  Commit 75a099fc734a4ee2b1347d0a3d8c53d883b95174 points to another
  
  maintainability issue : Contrary to ordinary DSP code, this code
  
  here is way more complex and needs to be constantly kept in sync
  
  with the ordinary code which it mimicks and replaces. Said commit
  
  is the only commit actually changing aaccoder.c in the last few
  
  years and the same change has not been performed for the MIPS
  
  clone ; before that, it even happened several times that the mips
  
  code was broken due to changes of the generic code (see commits
  
  97437bd17a8c5d4135b2f3b1b299bd7bb72ce02c and
  
  de262d018d7d7d9c967af1dfd1b861c4b9eb2a60 or
  
  860dbe0275e57cbf4228f3f653f872ff66ca596b or
  
  933309a6ca0f18bf1d40e917fff455221f57fb4b or
  
  b65ffa316e377213c29736929beba584d0d80d7c). This might even lead
  
  to scenarios where someone changing non-dsp aacenc code would
  
  have to modify mips inline asm in order to keep them in sync.
  
  This is obviously a significant burden (if the AAC encoder were
  
  actively developed).
  Finally, the code does not even compile here due to errors like
  
  "Error : float register should be even, was 1".
  Reviewed-by : Lynne <dev@lynne.ee>
  
  Reviewed-by : Jean-Baptiste Kempf <jb@videolan.org>
  
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/aacenc.c
  • [DH] libavcodec/aacenc.h
  • [DH] libavcodec/mips/Makefile
  • [DH] libavcodec/mips/aaccoder_mips.c

• avcodec/ffv1dec : Switch to ProgressFrames

  2 septembre 2022, par Andreas Rheinhardt

  avcodec/ffv1dec : Switch to ProgressFrames
  Avoids implicit av_frame_ref() and therefore allocations
  
  and error checks. It also avoids explicitly allocating
  
  the AVFrames (done implicitly when getting the buffer).
  It also fixes a data race : The AVFrame's sample_aspect_ratio
  
  is currently updated after ff_thread_finish_setup()
  
  and this write is unsynchronized with the read in av_frame_ref().
  
  Removing the implicit av_frame_ref() fixed this.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/ffv1.h
  • [DH] libavcodec/ffv1dec.c