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• ffmpeg in child process doesn't exit when parent closes pipe

  28 mars 2013, par user2221129

  This code snippet is from a pthread process. It is responsible for reading configuration/options to pass to ffmpeg. The data piped to ffmpeg is coming in on a ring buffer of video frames (as a proof of concept, in the final implementation these would be coming from a camera device). The parent writes to the child via a pipe established with dup2. The problem I'm having is that most of the time, the ffmpeg process doesn't seem to recognize the pipe has been closed by the parent (as strace shows the ffmpeg is in read). There are probably some unhandled mutex situations.

  #define CHILD_READ  writepipe[0]
  
  #define PARENT_WRITE    writepipe[1]
  
  #define MAX_VIDEO_BUFFERS 30
  
  
  
  static int last_frame_written = -1;
  
  static int buffer_size = -1;
  
  static void *video_buffer[MAX_VIDEO_BUFFERS];
  
  
  
  #define MAXTHREADS 2
  
  static pthread_t thread[MAXTHREADS];
  
  static int sigusr[MAXTHREADS];
  
  static int sigusr_thread[MAXTHREADS];
  
  
  
  #define MAXPARAMETERS 100
  
  
  
  void* encoder_thread(void *ptr)
  
  {
  
      int param;
  
      const char **parameters = new const char* [MAXPARAMETERS];
  
      ssize_t bytes_written_debug = 0;
  
  
  
      int writepipe[2] = {-1,-1};
  
      int last_frame_read = -1;
  
      pid_t   childpid;
  
  
  
      // xxx
  
      if ( 0 != pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL) )
  
      {
  
          fprintf(stderr,"pthread_setcancelstate could not be set\n");
  
      }
  
  
  
      param = *(int*)ptr;
  
      fprintf(stderr,"param = %d\n", param);
  
  
  
      switch (param)
  
      {
  
          ...read config file and populate parameters for child call...
  
      }
  
  
  
      while ( last_frame_written == -1 )
  
      {
  
          fprintf(stderr,"ENCODER THREAD WAITING\n");
  
          sleep(1);
  
      }
  
  
  
      if ( pipe(writepipe) < 0 )
  
      {
  
          ...handle error case...
  
      }
  
  
  
  
  
      if ( (childpid = fork()) < 0)
  
      {
  
          fprintf(stderr,"child failed\n");
  
      }
  
      else if ( 0 == childpid )   /* in the child */
  
      {
  
          dup2(CHILD_READ,  STDIN_FILENO);
  
          //close(CHILD_READ); // doesn't seem to matter
  
          close(PARENT_WRITE);
  
  
  
          execv("/usr/bin/ffmpeg",(char **)parameters);
  
          return;
  
      }
  
      else                /* in the parent */
  
      {
  
          fprintf(stderr,"THREAD CHILD PID: %d\n",childpid);
  
          close(CHILD_READ);
  
  
  
          while ( last_frame_written > -1 && 0==sigusr_thread[param] )
  
          {
  
              if ( last_frame_read != last_frame_written )
  
              {
  
                  // send frame to child (ffmpeg)
  
                  last_frame_read = last_frame_written;
  
                  bytes_written_debug = write(PARENT_WRITE,video_buffer[last_frame_read], buffer_size);
  
                  if ( bytes_written_debug < 0 )
  
                  {
  
                      fprintf(stderr, "write error\n");
  
                      break;
  
                  }
  
              }
  
  
  
              usleep(10000); // assume ~100Hz rate
  
          }
  
  
  
  /// Problems begin now: no more data from main process,
  
  /// Shouldn't this close "close" the pipe created with dup2 and hence EOF ffmpeg?
  
          if ( close(PARENT_WRITE) )
  
          {
  
              fprintf(stderr,"\n\nclose failure! wtf?\n\n\n");
  
          }
  
  
  
  // debug sleep:
  
  // waiting 10 sec doesn't seem to help...
  
  // trying to give ffmpeg some time if it needs it
  
          sleep(10);
  
  
  
  // kill never fails here:
  
          if ( !kill(childpid,SIGINT) )
  
          {
  
              fprintf(stderr, "\n\nkill child %d\n", childpid);
  
          }
  
          else
  
          {
  
              fprintf(stderr, "\n\nkill failed for child %d\n", childpid);
  
          }
  
  
  
          fprintf(stderr,"\n\nwaiting\n\n\n");
  
          int status = 0;
  
  
  
  // wait forever (in most cases); ps -axw shows all the ffmpeg's
  
          wait(&status);
  
      }
  
  }
  
  
  
  
  
  
  
  
  
  int main()
  
  {
  
      ...
  
      for ( int i = 0; i < MAXTHREADS; ++i)
  
      {
  
          sigusr[i] = 0;
  
          sigusr_thread[i] = 0;
  
          param[i] = i;
  
          iret = pthread_create( &thread[i], NULL, encoder_thread, (void*) &param[i] );
  
      }
  
      ...
  
  
  
      // Maybe this is important to the pthread signaling?
  
      // Don't think so because thread's SIGINT isn't picked up by signal handler (not shown)
  
      sigemptyset(&set);
  
      sigaddset(&set, SIGHUP);
  
      sigaddset(&set, SIGINT);
  
      sigaddset(&set, SIGUSR1);
  
      sigaddset(&set, SIGUSR2);
  
      sigaddset(&set, SIGALRM);
  
  
  
      /* block out these signals */
  
      sigprocmask(SIG_BLOCK, &set, NULL);
  
  
  
      ...read file/populate frame buffer until file exhausted...
  
  
  
      fprintf(stderr, "waiting for threads to exit\n");
  
  
  
      for ( int i = 0; i < MAXTHREADS; ++i)
  
      {
  
          sigusr_thread[i] = 1;
  
          pthread_join( thread[i], NULL);
  
      }
  
      fprintf(stderr, "done waiting for threads to exit\n");
  
  
  
      ...
  
  
  
      return 0;
  
  }

  I've embedded comments and questions in the thread's parent code after the frame buffer read/write loop.

  Hope I've provided enough detail - stackoverflow posting noob ! Thank you.

• shared library built with g++ compile is works and with automake compile can not be used

  23 avril 2013, par user2310175

  I'm building a shared libraries on CentOS 6.2.
  The shared library will be build have some cpp files,headers,c shared libraries
  and ffmpeg.The shared library is used to convert videos. When i use the g++ compile like this :

  g++    DataType.h    h264function.h  h264function.cpp videoconvert.h videoconvert.cpp      stdafx.h stdafx.cpp YV12toRGB.h YV12toRGB.cpp -lMPCtrl -lavcodec -lavformat -lavutil -   lhcnetsdk -lPlayCtrl -lpthread -fPIC -shared -o libtest.so

  It can work properly,and the video can be converted as standard h264 coded.That seems the files used for building the library is

  good.But when i use the autotools to make the library,it can not work correct.Here is my configure.in and Makefile.am :

  Makefile.am :

  prefix=/usr
  
  lib_LTLIBRARIES=libhikvisiontranso.la
  
  
  
  libhikvisiontranso_la_SOURCES=stdafx.h stdafx.cpp videoconvert.h videoconvert.cpp 
  
  h264function.h h264function.cpp YV12toRGB.h YV12toRGB.cpp DataType.h 
  
  
  
  libhikvisiontranso_la_LDFLAGS=-avoid-version -shared 
  
  libhikvisiontranso_la_LIBADD=-lpthread -lMPCtrl -lhcnetsdk -lPlayCtrl -lavformat -    lavcodec -lavutil
  
  ACLOCAL_AMFLAGS= -I m4

  configure.in :

  #                                               -*- Autoconf -*-
  
  # Process this file with autoconf to produce a configure script.
  
  
  
  AC_PREREQ([2.63])
  
  AC_INIT([hikvisiontranso],[1.0], [songxiawuren@gmail.com])
  
  AM_INIT_AUTOMAKE([libhikvisiontranso.so],[1.0])
  
  AC_CONFIG_SRCDIR([DataType.h])
  
  AC_CONFIG_HEADERS([config.h])
  
  AC_CONFIG_MACRO_DIR([m4])
  
  AT_INIT
  
  # Checks for programs.
  
  AC_PROG_CXX
  
  AC_PROG_CC
  
  
  
  # Checks for libraries.
  
  
  
  # Checks for header files.
  
  AC_CHECK_HEADERS([inttypes.h limits.h stddef.h stdint.h stdlib.h string.h])
  
  
  
  # Checks for typedefs, structures, and compiler characteristics.
  
  AC_HEADER_STDBOOL
  
  AC_C_INLINE
  
  AC_TYPE_INT16_T
  
  AC_TYPE_INT32_T
  
  AC_TYPE_INT64_T
  
  AC_TYPE_INT8_T
  
  AC_TYPE_SIZE_T
  
  AC_TYPE_UINT16_T
  
  AC_TYPE_UINT32_T
  
  AC_TYPE_UINT64_T
  
  AC_TYPE_UINT8_T
  
  
  
  # Checks for library functions.
  
  AC_FUNC_MALLOC
  
  AC_PROG_LIBTOOL
  
  AC_CONFIG_FILES([Makefile])
  
  AC_OUTPUT

  The wrong output is :

  SDL Init
  
  
  
  init console=1
  
  
  
  Output #0, avi, to '/home/ningge/Desktop/HaikangDvr.avi':
  
  
  
  Stream #0.0: Invalid Codec type -1
  
  
  
  Height = 576; Width = 704;totalfram=90000
  
  
  
  Segmentation fault (core dumped)

  The right is :

  SDL Init
  
  
  
  init console=1
  
  
  
  Output #0, avi, to '/home/ningge/Desktop/HaikangDvr.avi':
  
  
  
  Stream #0.0: Video: mpeg4, yuv420p, 704x576, q=2-31, 200 kb/s, 90k tbn, 25 tbc
  
  
  
  Height = 576; Width = 704;totalfram=90000
  
  
  
  CSDLInit goOut 

  I hope someone can help me to find what's wrong with automake.

• Missing functions in new version of FFmpeg

  25 avril 2013, par Asik

  I am upgrading a wrapper around ffmpeg to the most recent version of the library. Some functions have been renamed or replaced. For the most part I've been able to found equivalents easily, but the following two are giving me trouble :

  av_abort_set_callback
  
  av_abort_default_callback

  I could not find these functions by searching online, so what happened to them and what should they be replaced with now ?

  Here is a copy of the header file "abort.h" where they were located :

  /* 
  
   * This file is part of FFmpeg. 
  
   * 
  
   * FFmpeg is free software; you can redistribute it and/or 
  
   * modify it under the terms of the GNU Lesser General Public 
  
   * License as published by the Free Software Foundation; either 
  
   * version 2.1 of the License, or (at your option) any later version. 
  
   * 
  
   * FFmpeg is distributed in the hope that it will be useful, 
  
   * but WITHOUT ANY WARRANTY; without even the implied warranty of 
  
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
  
   * Lesser General Public License for more details. 
  
   * 
  
   * You should have received a copy of the GNU Lesser General Public 
  
   * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 
  
   */
  
  
  
  #ifndef AVUTIL_ABORT_H
  
  #define AVUTIL_ABORT_H
  
  
  
  /** 
  
   * Causes abnormal program termination. By default, av_abort_callback calls 
  
   * abort() from the stdlib. This behavior can be altered by setting a 
  
   * different av_abort callback function. 
  
   */
  
  
  
  void av_abort_internal(void);
  
  void av_abort_set_callback(void (*)(void));
  
  void av_abort_default_callback(void);
  
  
  
  #define av_abort()    do { av_log(NULL, AV_LOG_ERROR, "Abort at %s:%d\n", __FILE__, __LINE__); av_abort_internal(); } while(0)
  
  
  
  #endif /* AVUTIL_ABORT_H */