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• errors when compiling c code with ffmpeg library

  2 mai 2017, par Kindermann

  I've installed ffmpeg library in my new ubuntu 16.04 OS. When I tried to compile my c code, I got the following strange errors:

  /home/widerstand/ffmpeg_build/lib/libavutil.a(hwcontext_vaapi.o): In function `vaapi_device_free':
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:861: undefined reference to `XCloseDisplay'
  /home/widerstand/ffmpeg_build/lib/libavutil.a(hwcontext_vaapi.o): In function `vaapi_device_create':
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:891: undefined reference to `XOpenDisplay'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:896: undefined reference to `vaGetDisplay'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:903: undefined reference to `XDisplayName'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:893: undefined reference to `XDisplayName'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:917: undefined reference to `vaGetDisplayDRM'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:891: undefined reference to `XOpenDisplay'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:893: undefined reference to `XDisplayName'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:898: undefined reference to `XDisplayName'
  /home/widerstand/ffmpeg_build/lib/libavutil.a(hwcontext_vdpau.o): In function `vdpau_device_create':
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vdpau.c:431: undefined reference to `XOpenDisplay'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vdpau.c:437: undefined reference to `XDisplayString'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vdpau.c:439: undefined reference to `XDefaultScreen'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vdpau.c:439: undefined reference to `vdp_device_create_x11'
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vdpau.c:433: undefined reference to `XDisplayName'
  /home/widerstand/ffmpeg_build/lib/libavutil.a(hwcontext_vdpau.o): In function `vdpau_device_free':
  /home/widerstand/ffmpeg_sources/ffmpeg/libavutil/hwcontext_vdpau.c:410: undefined reference to `XCloseDisplay'
  collect2: error: ld returned 1 exit status
  Makefile:30: recipe for target 'video_analysis' failed
  make: *** [video_analysis] Error 1
  

  I've reinstalled ffmpeg library multiple times using the following configurations:

  PATH="$HOME/bin:$PATH" PKG_CONFIG_PATH="$HOME/ffmpeg_build/lib/pkgconfig" ./configure \
    --prefix="$HOME/ffmpeg_build" \
    --pkg-config-flags="--static" \
    --extra-cflags="-I$HOME/ffmpeg_build/include" \
    --extra-ldflags="-L$HOME/ffmpeg_build/lib" \
    --bindir="$HOME/bin" \
    --enable-gpl \
    --enable-libass \
    --enable-libfdk-aac \
    --enable-libfreetype \
    --enable-libmp3lame \
    --enable-libopus \
    --enable-libtheora \
    --enable-libvorbis \
    --enable-libvpx \
    --enable-libx264 \
    --enable-nonfree
  PATH="$HOME/bin:$PATH" make
  

  The installation process was successful each time. But when I tried to compile my own c code, I always encountered the same errors as mentioned above. I have no idea about that... Here is the makefile I used:

  EDIT:

  FFMPEG_LIBS=    libavdevice                        \
                  libavformat                        \
                  libavfilter                        \
                  libavcodec                         \
                  libswresample                      \
                  libswscale                         \
                  libavutil                          \
  
  TARGET = video_analysis
  LIBS = -lX11 -lm -lvdpau -lva
  CC = gcc
  CFLAGS += -O2 -g -O0
  CFLAGS := $(shell pkg-config --cflags $(FFMPEG_LIBS)) $(CFLAGS)
  LDLIBS := $(shell pkg-config --libs $(FFMPEG_LIBS)) $(LDLIBS)
  
  .PHONY: default all clean
  
  default: $(TARGET)
  all: default
  
  OBJECTS = $(patsubst %.c, %.o, $(wildcard *.c))
  HEADERS = $(wildcard *.h)
  
  %.o: %.c $(HEADERS)
      $(CC) $(CFLAGS) -c $< -o $@
  
  .PRECIOUS: $(TARGET) $(OBJECTS)
  
  $(TARGET): $(OBJECTS)
      $(CC) $(OBJECTS) $(LDLIBS) $(LIBS) -o $@
  
  clean:
      -rm -f *.o
      -rm -f $(TARGET)
  

  EDIT:

  Afer swapping $(LIBS) and $(LDLIBS) to be $(LDLIBS) $(LIBS) at line 30, it looks much better, but the compiler still reports the following errors:

  /root/ffmpeg_build/lib/libavutil.a(hwcontext_vaapi.o): In function `vaapi_device_create':
  /ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:896: undefined reference to `vaGetDisplay'
  /ffmpeg_sources/ffmpeg/libavutil/hwcontext_vaapi.c:917: undefined reference to `vaGetDisplayDRM'
  

  I have no idea which library is still missing? It looks as if libva were still missing?... I got the answer by myself...Have a look at here: errors of 'vaGetDisplay' and `vaGetDisplayDRM'

• Capture FFMPEG output

  2 mai 2017, par Andrew

  I need to read the output from ffmpeg in order to even try the solution to my question from yesterday. This is a separate issue from my problem there, so I made a new question.

  How the heck do I get the output from an ffmpeg -i command in PHP?

  This is what I've been trying:

  <?PHP
      error_reporting(E_ALL);
      $src = "/var/videos/video1.wmv";
      $command = "/usr/bin/ffmpeg -i " . $src;
      echo "",$command,"
  ";
      $command = escapeshellcmd($command);
  
      echo "backtick:
  ";
      `$command`;
  
      echo "
  
  system:
  ";
      echo system($command);
  
      echo "
  
  shell_exec:
  ";
      echo shell_exec($command);
  
      echo "
  
  passthru:
  ";
      passthru($command);
  
      echo "
  
  exec:
  ";
      $output = array();
      exec($command,$output,$status);
      foreach($output AS $o)
      {
              echo $o , "
  ";
      }
      echo "
  
  popen:
  ";
      $handle = popen($command,'r');
      echo fread($handle,1048576);
      pclose($handle);
      echo "
  
  ";
  ?>
  

  This is my output:

  /usr/bin/ffmpeg -i /var/videos/video1.wmv
  
  backtick:
  
      
  
  
  system:
  
      
  
  
  shell_exec:
  
      
  
  
  passthru:
  
      
  
  
  exec:
  
      
  
  
  popen:
  
      
  
  
  

  I don't get it. safe_mode is off. There's nothing in disable_functions. The directory is owned by www-data (the apache user on my Ubuntu system). I get a valid status back from exec() and system() and running the same command from the command line give me tons of output. I feel like I must be missing something obvious but I have no idea what it is.

• rescale with ffmpeg but keep the pixel density constant

  2 mai 2017, par rinofcan

  I have a 1280x720 video resolution After I resized the video output was blurred more than the original video How to output video is clearer

• FFMPEG Recode all audio streams while keeping originals

  2 mai 2017, par Olirav

  I am trying to add a additional set of audio tracks into some video files, as part of a automated process. I would like to keep all the original audio tracks and have a second re-coded copy.

  What I have been using is:

  ffmpeg -i file
  -map 0:v -codec:v copy
  -map 0:a -codec:a copy
  -map 0:a:0 -codec:a:0 aac -strict experimental ...(Bitrate, filters etc all with :a:0)
  -map 0:s -codec:s copy
  output file
  

  However I can't work out how to change this to handle input files that have multiple audio tracks as it will only convert the first.

  If I change the :a:0 to :a on the codec line it produces the extra copy I need but overrides the copy codec for the original copy.

  Any ideas anyone?

• Reading encoded data using muxing in ffmpeg

  2 mai 2017, par Sanduni Wickramasinghe

  I am trying to read an encoded video using ffmpeg c++. When I try to build my code error appears as identifier options is undefined. But it is already defined as AVDictionary *options = NULL.

  What is wrong with my code?

  void CFfmpegmethods::VideoRead(){
  
      const char *url = "H:/Sanduni_projects/ad_2.mp4";
  
      AVFormatContext *s = NULL;
      int ret = avformat_open_input(&s, url, NULL, NULL);
      if (ret < 0)
          abort();
  
      avformat_find_stream_info(s, &options);
  
      AVDictionary *options = NULL;
  
      av_dict_set(&options, "video_size", "640x480", 0);
      av_dict_set(&options, "pixel_format", "rgb24", 0);
  
      if (avformat_open_input(&s, url, NULL, &options) < 0){
          abort();
      }
  
      av_dict_free(&options);
  
      AVDictionaryEntry *e;
  
      if (e = av_dict_get(options, "", NULL, AV_DICT_IGNORE_SUFFIX)) {
          fprintf(stderr, "Option %s not recognized by the demuxer.\n", e->key);
          abort();
      }
  
      avformat_close_input(&s);
  }