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• OSX MistServer/FFMPEG : RTMP Input/Output error

  28 septembre 2017, par brewcrazy

  I have an IP camera that outputs a RTSP stream that I’m trying to use to display a live feed on my website. This is a small site that only my wife and I will access so I’m trying to use a free streaming service. For that reason, I’ve decided to try MistServer’s open source option.

  I currently have downloaded MistServer and have it running without installation on my mac (sudo ./MistController). With MistServer running, I have a stream set up and default protocols configured. The stream is configured as follows :

  stream name: ipcam
  
  source: push://

  The configuration page gives me the following source to push to :

  RTMP full url: rtmp://127.0.0.1/live/ipcam
  
  RTMP url: rtmp://127.0.0.1/live/
  
  RTMP stream key: ipcam

  In the streams view, the stream’s status is unavailable, but I’m assuming this is because it isn’t receiving an input. I haven’t been able to confirm this via documentation.

  Here is the FFMPEG command that I am running and the error that I’m getting :

  ffmpeg -rtsp_transport tcp -i rtsp://<user>:@:554/live0.264 -acodec copy -vcodec copy -f flv rtmp://127.0.0.1/live/ipcam
  
  
  
  ffmpeg version 3.3.3 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with Apple LLVM version 8.1.0 (clang-802.0.42)
  
    configuration: --prefix=/usr/local/Cellar/ffmpeg/3.3.3 --enable-shared --enable-pthreads --enable-gpl --enable-version3 --enable-hardcoded-tables --enable-avresample --cc=clang --host-cflags= --host-ldflags= --enable-libmp3lame --enable-libx264 --enable-libxvid --enable-opencl --enable-videotoolbox --disable-lzma --enable-vda
  
    libavutil      55. 58.100 / 55. 58.100
  
    libavcodec     57. 89.100 / 57. 89.100
  
    libavformat    57. 71.100 / 57. 71.100
  
    libavdevice    57.  6.100 / 57.  6.100
  
    libavfilter     6. 82.100 /  6. 82.100
  
    libavresample   3.  5.  0 /  3.  5.  0
  
    libswscale      4.  6.100 /  4.  6.100
  
    libswresample   2.  7.100 /  2.  7.100
  
    libpostproc    54.  5.100 / 54.  5.100
  
  Guessed Channel Layout for Input Stream #0.1 : mono
  
  Input #0, rtsp, from 'rtsp://admin:@192.168.10.112:554/live0.264':
  
    Metadata:
  
      title           : Session Streamed by LIBZRTSP
  
      comment         : live0.264
  
    Duration: N/A, start: 0.242000, bitrate: N/A
  
      Stream #0:0: Video: h264 (Main), yuv420p(progressive), 1280x720, 25 fps, 24.83 tbr, 90k tbn, 50 tbc
  
      Stream #0:1: Audio: pcm_mulaw, 8000 Hz, mono, s16, 64 kb/s
  
  rtmp://127.0.0.1/live/ipcam: Input/output error
  
  </user>

  I can’t determine from this error if the issue is the FFMPEG command or my MistServer configuration.

• Including objects to a shared library from a C++ archive (.a)

  1er septembre 2021, par El Sampsa

  I am trying to include some object files into a shared library I am building. Take the following command (things in [ETC] have been omitted for brevity) :

  



  


  /usr/bin/c++ -fPIC -std=c++14 -pthread -Iinclude/ext/liveMedia -Iinclude/ext/groupsock [ETC] -g -shared -Wl,-soname,libValkka.so -o lib/libValkka.so CMakeFiles/Valkka.dir/src/avthread.cpp.o CMakeFiles/Valkka.dir/src/opengl.cpp.o [ETC] CMakeFiles/Valkka.dir/src/decoders.cpp.o -lX11 -lGLEW -lGLU -lGL -Wl,—whole-archive lib/libavcodec.a -Wl,—no-whole-archive

  


  



  So basically I am just creating a shared library where most of the objects come from my own source code (i.e. CMakeFiles/Valkka.dir/src/*.o), but some of them come from an external static library, located at "lib/libavcodec.a". I get the following error :

  



  


  /usr/bin/ld : lib/libavcodec.a(h264_cabac.o) : relocation R_X86_64_PC32 against symbol 'ff_h264_cabac_tables' can not be used when making a shared object ; recompile with -fPIC
 /usr/bin/ld : final link failed : Bad value
 collect2 : error : ld returned 1 exit status

  


  



  But that is so untrue ! I can extract "libavcodec.a" with

  



  ar x libavcodec.a


  



  And after that check that

  



  readelf --relocs h264_cabac.o | egrep '(GOT|PLT|JU?MP_SLOT)' 


  



  does give some **it :

  



  


  00000000175d 003100000004 R_X86_64_PLT32 0000000000000000 __stack_chk_fail - 4
 000000001926 003100000004 R_X86_64_PLT32 0000000000000000 __stack_chk_fail - 4

  
 


  ...

  


  



  As does

  



  objdump -r h264_cabac.o | grep -i "relocation"


  



  So, indeed, the object files in "libavcodec.a" have been compiled to get PIC (position independent code).

  



  Why does the linker believe otherwise !?

  



  Related links :

  



  How to include all objects of an archive in a shared object ?

  



  Linking archives (.a) into shared object (.so)

  



  Is there a way to determine that a .a or .so library has been compiled as position indepenent code ?

  



  How can I tell, with something like objdump, if an object file has been built with -fPIC ?

  


• Audio drift issue. Creating video frames programmatically and syncing with midi/audio in java

  6 septembre 2017, par user6688986

  I want to create a video that changes to the notes on a midi file. I am recording the midi then outputting it as wav.

  In java I read the midi file, create images based on the notes played. I am calculating the time between notes and using this to determine the number of frames with this code :

      for(int i = 0; i < noteImages.size(); i++) {
  
          for(int j = 0; j < frameRate * (noteLengths.get(i) / 1000); j++) {
  
              videoFrames.add(noteImages.get(i));
  
              frameCount++;
  
          }
  
      }

  I then use ffmpeg to create the video from the images with audio using this command :

  ffmpeg -r 60 -f image2 -i pic%05d.png -itsoffset 3 -i audio.wav -c:v libx264 -c:a aac -pix_fmt yuv420p -crf 23 -r 24 -shortest -y output.mp4 

  The audio starts okay then gradually goes out of sync. If I use higher fps when creating the images it is less pronounced, but I need to use at least 300fps to get it close and it is still not quite right. Any ideas on how to correct this ?