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• Multiprocess FATE Revisited

  26 juin 2010, par Multimedia Mike — FATE Server, Python

  I thought I had brainstormed a simple, elegant, multithreaded, deadlock-free refactoring for FATE in a previous post. However, I sort of glossed over the test ordering logic which I had not yet prototyped. The grim, possibly deadlock-afflicted reality is that the main thread needs to be notified as tests are completed. So, the main thread sends test specs through a queue to be executed by n tester threads and those threads send results to a results aggregator thread. Additionally, the results aggregator will need to send completed test IDs back to the main thread.

  
  
  

  But when I step back and look at the graph, I can’t rationalize why there should be a separate results aggregator thread. That was added to cut down on deadlock possibilities since the main thread and the tester threads would not be waiting for data from each other. Now that I’ve come to terms with the fact that the main and the testers need to exchange data in realtime, I think I can safely eliminate the result thread. Adding more threads is not the best way to guard against race conditions and deadlocks. Ask xine.

  
  
  

  I’m still hung up on the deadlock issue. I have these queues through which the threads communicate. At issue is the fact that they can cause a thread to block when inserting an item if the queue is "full". How full is full ? Immaterial ; seeking to answer such a question is not how you guard against race conditions. Rather, it seems to me that one side should be doing non-blocking queue operations.

  This is how I’m planning to revise the logic in the main thread :

  test_set = set of all tests to execute
  tests_pending = test_set
  tests_blocked = empty set
  tests_queue = multi-consumer queue to send test specs to tester threads
  results_queue = multi-producer queue through which tester threads send results
  while there are tests in tests_pending :
    pop a test from test_set
    if test depends on any tests that appear in tests_pending :
      add test to tests_blocked
    else :
      add test to tests_queue in a non-blocking manner
      if tests_queue is full, add test to tests_blocked
    while there are results in the results_queue :
  
      get a result from result_queue in non-blocking manner
  
      remove the corresponding test from tests_pending
  if tests_blocked is non-empty :
  
    sleep for 1 second
  
    test_set = tests_blocked
  
    tests_blocked = empty set
  
  else :
  
    insert n shutdown signals, one from each thread
  go to the top of the loop and repeat until there are no more tests
  while there are results in the results_queue :
  
    get a result from result_queue in a blocking manner
  

  Not mentioned in the pseudocode (so it doesn’t get too verbose) is logic to check whether the retrieved test result is actually an end-of-thread signal. These are accounted and the whole test process is done when one is received for each thread.

  On the tester thread side, it’s safe for them to do blocking test queue retrievals and blocking result queue insertions. The reason for the 1-second delay before resetting tests_blocked and looping again is because I want to guard against the situation where tests A and B are to be run, A depends of B running first, and while B is running (and happens to be a long encoding test), the main thread is spinning about, obsessively testing whether it’s time to insert A into the tests queue.

  It all sounds just crazy enough to work. In fact, I coded it up and it does work, sort of. The queue gets blocked pretty quickly. Instead of sleeping, I decided it’s better to perform the put operation using a 1-second timeout.

  Still, I’m paranoid about the precise operation of the IPC queue mechanism at work here. What happens if I try to stuff in a test spec that’s a bit too large ? Will the module take whatever I give it and serialize it through the queue as soon as it can ? I think an impromptu science project is in order.

  big-queue.py :

  PLAIN TEXT

  PYTHON :

  1. # !/usr/bin/python
  2.  
  3. import multiprocessing
  4. import Queue
  5.  
  6. def f(q) :
  7.   str = q.get()
  8.   print "reader function got a string of %d characters" % (len(str))
  9.  
  10. q = multiprocessing.Queue()
  11. p = multiprocessing.Process(target=f, args=(q,))
  12. p.start()
  13. try :
  14.   q.put_nowait(’a’ * 100000000)
  15. except Queue.Full :
  16.   print "queue full"

  $ ./big-queue.py
  reader function got a string of 100000000 characters
  

  Since 100 MB doesn’t even make it choke, FATE’s little test specs shouldn’t pose any difficulty.

• Is this a problem in my command, the stream, or FFMPEG itself ? [closed]

  10 juin, par Ali Mustafa

  I am trying to download a section from approximately 06:40:00 to 06:44:00 from this stream : https://kick.com/grossgore/videos/8d36c089-ff2b-4167-9c92-bc8a3a9d033b

  


  I found the m3u8 URL : https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/playlist.m3u8

  


  I run the following command :

  


  ffmpeg -ss 06:40:00 -to 06:44:00 -i https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/playlist.m3u8 -c copy out.mp4


  


  The command runs for a while, but for some reason the output file is empty once the program has finished. How do I figure out what the problem is ?

  


  Log :

  


  ffmpeg version 4.4.2-0ubuntu0.22.04.1 Copyright (c) 2000-2021 the FFmpeg developers
  built with gcc 11 (Ubuntu 11.2.0-19ubuntu1)
  configuration: --prefix=/usr --extra-version=0ubuntu0.22.04.1 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sdl2 --enable-pocketsphinx --enable-librsvg --enable-libmfx --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 70.100 / 56. 70.100
  libavcodec     58.134.100 / 58.134.100
  libavformat    58. 76.100 / 58. 76.100
  libavdevice    58. 13.100 / 58. 13.100
  libavfilter     7.110.100 /  7.110.100
  libswscale      5.  9.100 /  5.  9.100
  libswresample   3.  9.100 /  3.  9.100
  libpostproc    55.  9.100 / 55.  9.100
[hls @ 0x633e19ea3200] Skip ('#EXT-X-VERSION:3')
[hls @ 0x633e19ea3200] Skip ('#ID3-EQUIV-TDTG:2025-05-25T21:04:39')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-TWITCH-ELAPSED-SECS:0.000')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-TWITCH-TOTAL-SECS:29231.935')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T12:56:26.675Z')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T12:56:39.175Z')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T12:56:51.675Z')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T12:57:04.175Z')
...
...
...
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T17:38:43.058Z')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T17:38:55.558Z')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-DISCONTINUITY')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-TWITCH-DISCONTINUITY')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T17:39:56.883Z')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T17:40:09.383Z')
...
...
...
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T21:04:17.516Z')
[hls @ 0x633e19ea3200] Skip ('#EXT-X-PROGRAM-DATE-TIME:2025-05-25T21:04:30.016Z')
[hls @ 0x633e19ea3200] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/0.ts' for reading
[hls @ 0x633e19ea3200] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/1.ts' for reading
Input #0, hls, from 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/playlist.m3u8':
  Duration: 08:07:11.94, start: 64.171000, bitrate: 0 kb/s
  Program 0 
    Metadata:
      variant_bitrate : 0
  Stream #0:0: Audio: aac (LC) ([15][0][0][0] / 0x000F), 48000 Hz, stereo, fltp
    Metadata:
      variant_bitrate : 0
  Stream #0:1: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 60 tbr, 90k tbn, 120 tbc
    Metadata:
      variant_bitrate : 0
  Stream #0:2: Data: timed_id3 (ID3  / 0x20334449)
    Metadata:
      variant_bitrate : 0
Output #0, mp4, to 'out.mp4':
  Metadata:
    encoder         : Lavf58.76.100
  Stream #0:0: Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 60 tbr, 90k tbn, 90k tbc
    Metadata:
      variant_bitrate : 0
  Stream #0:1: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp
    Metadata:
      variant_bitrate : 0
Stream mapping:
  Stream #0:1 -> #0:0 (copy)
  Stream #0:0 -> #0:1 (copy)
Press [q] to stop, [?] for help
[hls @ 0x633e19ea3200] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/1921.ts' for reading
[hls @ 0x633e19ea3200] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/1922.ts' for reading
[https @ 0x633e1a43f9c0] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/1923.ts' for reading
[https @ 0x633e1a877300] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/1924.ts' for reading
[https @ 0x633e1a43f9c0] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/1925.ts' for reading
[https @ 0x633e1a877300] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/1926.ts' for reading
...
...
...
[https @ 0x633e1a877300] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/2338.ts' for reading
[https @ 0x633e1a43f9c0] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/2339.ts' for reading
[https @ 0x633e1a877300] Opening 'https://stream.kick.com/ivs/v1/196233775518/hDSBAWziz2jA/2025/5/25/12/56/LrW3TwZUg7Xk/media/hls/1080p60/2340.ts' for reading
frame=    0 fps=0.0 q=-1.0 Lsize=       0kB time=00:00:00.00 bitrate=N/A speed=   0x    
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown


  


• FFmpeg RTSP stream to remote MediaMTX server disconnects after a few seconds [closed]

  13 juin, par Rorschy

  I'm new to RTSP and MediaMTX, and I'm trying to live stream my screen using FFmpeg and MediaMTX for a specific use case.

  


  Everything works perfectly when both FFmpeg and MediaMTX run on the same machine.
However, when I move MediaMTX to a remote server, the stream becomes unstable — I can't maintain a connection or view the stream reliably.

  


  Here is the FFmpeg command I'm using from the client machine :

  


  ffmpeg -f gdigrab -framerate 10 -offset_x 0 -offset_y 0 -video_size 1920x1080 -i desktop -f lavfi -i anullsrc -vcodec libx264 -tune zerolatency -g 30 -sc_threshold 0 -preset ultrafast -tune zerolatency -f rtsp rtsp:///live/stream


  


  And here’s the relevant MediaMTX log output on the remote server :

  


  2025/06/12 14:28:44 INF [RTSP] [conn :35798] opened
2025/06/12 14:28:44 INF [RTSP] [session 2e487869] created by :35798
2025/06/12 14:28:44 INF [RTSP] [session 2e487869] is publishing to path 'live/stream', 2 tracks (H264, MPEG-4 Audio)
2025/06/12 14:28:45 INF [WebRTC] [session 8a909818] created by :47296
2025/06/12 14:28:45 WAR [WebRTC] [session 8a909818] skipping track 2 (MPEG-4 Audio)
2025/06/12 14:28:47 INF [WebRTC] [session dd0d3af7] created by :46306
2025/06/12 14:28:47 WAR [WebRTC] [session dd0d3af7] skipping track 2 (MPEG-4 Audio)
2025/06/12 14:28:49 INF [WebRTC] [session 5f853024] created by :46320
2025/06/12 14:28:49 WAR [WebRTC] [session 5f853024] skipping track 2 (MPEG-4 Audio)
2025/06/12 14:28:51 INF [WebRTC] [session 3edba9a8] created by :46342
2025/06/12 14:28:51 WAR [WebRTC] [session 3edba9a8] skipping track 2 (MPEG-4 Audio)
2025/06/12 14:28:53 INF [WebRTC] [session 4be5bd9b] created by :46352
2025/06/12 14:28:53 WAR [WebRTC] [session 4be5bd9b] skipping track 2 (MPEG-4 Audio)
2025/06/12 14:28:54 INF [RTSP] [conn :35798] closed: terminated
2025/06/12 14:28:54 INF [RTSP] [session 2e487869] destroyed: session timed out
2025/06/12 14:28:54 INF [WebRTC] [session 8a909818] closed: terminated
2025/06/12 14:28:54 INF [WebRTC] [session 3edba9a8] closed: terminated
2025/06/12 14:28:54 INF [WebRTC] [session 5f853024] closed: terminated


  


  My questions :

  


  

  1. What could be causing the RTSP stream to disconnect when streaming to a remote MediaMTX server ?

  


  2. Are there any recommended network settings or MediaMTX configuration tweaks to ensure a stable stream over the internet ?

  


  


  Any help or guidance would be greatly appreciated. Thanks !