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• application using ffmpeg segfaults because of for loop ?

  6 décembre 2012, par larvyde

  I am writing my first ffmpeg application using the tutorial linked to from the ffmpeg.org documentation page [tutorial] [sample]. Here is my initial code :

  const char * fnmVideoIn = argv [1];
  
  const char * fnmImageOut = argv [2];
  
  
  
  av_register_all ();
  
  
  
  // [] Open the file
  
  AVFormatContext * pcxFormat;
  
  if (avformat_open_input (&pcxFormat, fnmVideoIn, NULL, NULL)) {
  
      fprintf (stderr, "Could not open file %s for reading\n",
  
              fnmVideoIn);
  
      return -1;
  
  }
  
  
  
  // [] Get stream information
  
  if (avformat_find_stream_info (pcxFormat, NULL) < 0) {
  
      fprintf (stderr, "Could not find stream info\n");
  
      return -1;
  
  }
  
  
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);

  and all is well. The program runs without errors and dumps the video info properly. but then I got to the next step...

  ...
  
  // [log] print stream info
  
  av_dump_format (pcxFormat, 0, fnmVideoIn, 0);
  
  
  
  int ixVideoStream = -1, ixStrm;
  
  for (ixStrm = 0; ixStrm < pcxFormat->nb_streams; ++ixStrm) {
  
      if (pcxFormat->streams [ixStrm]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
  
          ixVideoStream = ixStrm;
  
          break;
  
      }
  
  }

  and it exits with a segfault. gdb says :

  (gdb) r test.mp4 out
  
  ...
  
  Program received signal SIGSEGV, Segmentation fault.
  
  0xb7f572c5 in avformat_open_input () from /usr/lib/libavformat.so.53

  how is it possible that avformat_open_input segfaults because of code added after it is called ? I even tested it with a regular i=0 ; i<100 for-loop and it still segfaults ! is this a bug ? For reference, my system is :

  $ gcc --version
  
  gcc (GCC) 4.7.0 20120414 (prerelease)
  
  
  
  $ uname -srvmpio
  
  Linux 3.3.4-1-ARCH #1 SMP PREEMPT Sat Apr 28 06:04:27 UTC 2012 i686 Intel(R) Core(TM)2 Duo CPU P7450 @ 2.13GHz GenuineIntel GNU/Linux
  
  
  
  $ ffmpeg -version
  
  ffmpeg version 0.10.2
  
  built on Mar 17 2012 08:53:01 with gcc 4.6.3
  
  configuration: --prefix=/usr --enable-libmp3lame --enable-libvorbis --enable-libxvid --enable-libx264 --enable-libvpx --enable-libtheora --enable-libgsm --enable-libspeex --enable-postproc --enable-shared --enable-x11grab --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libschroedinger --enable-libopenjpeg --enable-librtmp --enable-libpulse --enable-gpl --enable-version3 --enable-runtime-cpudetect --disable-debug --disable-static
  
  libavutil      51. 35.100 / 51. 35.100
  
  libavcodec     53. 61.100 / 53. 61.100
  
  libavformat    53. 32.100 / 53. 32.100
  
  libavdevice    53.  4.100 / 53.  4.100
  
  libavfilter     2. 61.100 /  2. 61.100
  
  libswscale      2.  1.100 /  2.  1.100
  
  libswresample   0.  6.100 /  0.  6.100
  
  libpostproc    52.  0.100 / 52.  0.100

• "File descriptor in bad state" error while running ffmpeg on android device and selecting an input device

  25 août 2012, par user1545779

  Below is the output of the ffmpeg command :# ./ffmpeg -y -f s16le -i /dev/snd/pcmC3D0c 1640.wmv -to create an audio file from a Logitech webcam on an android device.

  As shown in the output, I received a File descriptor in bad state error for referring to the mic input as /dev/snd/pcmC3D0c I determined the value of the device (webcam mic) by reviewing the contents of /proc/asound. The webcam mic was card3 and its STREAM0 file indicated that the mic has an audio format of format S16_LE

  It was also confirmed that it is a capture device and its' pcm id was pcmC3D0c (C3 being the card number and D0 being the Device number. I then confirmed the correct device by checking the /dev/snd/ directory to confirm its proper and full description. The /dev/snd folder confirmed that the mic was /dev/snd/pcmC3D0c

  I then checked the permissions and ownership to make sure that I could use that device. Hence as far as identifying the correct device to used I do believe that /dev/snd/pcmC3D0c is the correct device. I do believe this error could possibly have something to do with the OS, however after all these checks, I still cannot figure out what is giving the bad file descriptor state error.

  Please note that I tested for different output formats, etc and that did not make any difference. Any leads or suggestions ?

  # ./ffmpeg -y -f s16le -i /dev/snd/pcmC3D0c 1640.wmv

  ffmpeg version N-43170-gd84dd35 Copyright (c) 2000-2012 the FFmpeg developers
  built on Aug 24 2012 09:16:05 with gcc 4.4.3 (GCC) configuration : —enable-cross-compile —arch=arm —cpu=cortex-a9 —target-os=linux —enable-runtime-cpudetect —prefix=/output —enable-pic —cross-prefix=/home/jasongipsyblues/Desktop/apps/android-ndk-r8b/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86/bin/arm-linux-androideabi- —sysroot=/home/jasongipsyblues/Desktop/apps/android-ndk-r8b/platforms/android-14/arch-arm —enable-version3 —enable-gpl —enable-memalign-hack —disable-doc —enable-yasm —enable-libx264 —enable-zlib —extra-cflags=-I../x264 —extra-ldflags='-L../x264 -lc'

  libavutil 51. 66.100 / 51. 66.100
  libavcodec 54. 48.100 / 54. 48.100
  libavformat 54. 22.100 / 54. 22.100
  libavdevice 54. 2.100 / 54. 2.100
  libavfilter 3. 5.102 / 3. 5.102
  libswscale 2. 1.100 / 2. 1.100
  libswresample 0. 15.100 / 0. 15.100
  libpostproc 52. 0.100 / 52. 0.100

  [s16le @ 0xfd84f0] Invalid sample rate 0 specified using default of 44100
  [s16le @ 0xfd84f0] Estimating duration from bitrate, this may be inaccurate
  Guessed Channel Layout for Input Stream #0.0 : mono
  Input #0, s16le, from '/dev/snd/pcmC3D0c' :
  Duration : N/A, bitrate : 705 kb/s
  Stream #0:0 : Audio : pcm_s16le, 44100 Hz, mono, s16, 705 kb/s
  Output #0, asf, to '1640.wmv' :
  Metadata :
  WM/EncodingSettings : Lavf54.22.100
  Stream #0:0 : Audio : wmav2 (a[1][0][0] / 0x0161), 44100 Hz, mono, s16, 128 kb/s
  Stream mapping :
  Stream #0:0 -> #0:0 (pcm_s16le -> wmav2)
  Press [q] to stop, [?] for help
  
  /dev/snd/pcmC3D0c : File descriptor in bad state
  size= 1kB time=00:00:00.00 bitrate= 0.0kbits/s
  video:0kB audio:0kB subtitle:0 global headers:0kB muxing overhead 5340.000000%

• How can I configure library dependencies in setup.py

  1er septembre 2021, par idontidontknowknow

  I want to pack a c++ project into python wheel package that user can install it by pip install myProject in different platform(like ubuntu, centos...), but the project is rely on a open source c library(ffmpeg).

  &#xA;

  I try to generate ffmpeg.so, then load it with ctypes.CDLL("ffmpeg.so", mode=RTLD_GLOBAL), it works in ubuntu(the same version with my development platform but no ffmpeg environment), but not works in centos.

  &#xA;

  What should I do that make the wheel package can pip and use in different platform without configuring dependencies again ?

  &#xA;