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• I am really confused with this kind of compilation error( C ffmpeg Qt)

  31 octobre 2016, par David Tree

  I downloaded the latest ffmpeg source code and successfully installed it on Ubuntu
  But I failed to compile a simple demo.(I did included proper headers)

  Here are the error messages ,just to name a few :

  error: unknown type name 'AVFrame'
  
  
  
  error: 'NULL' undeclared (first use in this function)
  
  
  
  error: request for member 'streams' in something not a structure or union
  
  
  
  error: 'AVMEDIA_TYPE_VIDEO' undeclared (first use in this function)
  
  
  
  error: expected expression before ')' token

  Can you help me solve this problem ?

  Contents Added :

  e.g this is my includes

  extern "C"{
  
  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  #include <libavutil></libavutil>avutil.h>
  
  }
  
  
  
  int main(int argc, char *argv[]) {
  
  AVFormatContext *pFormatCtx;
  
  int i, videoStreamIdx;
  
  AVCodecContext *pCodecCtx;
  
  AVCodec *pCodec;
  
  AVFrame *pFrame;
  
  AVFrame *pFrameRGB;

  e.g AVFormatContext is declared in /usr/include/libavformat/avformat.h
  error message box shows Unknown type name AVFormatContext
  But How could it possibly be ?

• ffmpeg, offset frame_num to start_frame when using drawtext

  22 novembre 2017, par stormy

  I’m converting a sequence of exr images to a mov with a text overlay. I’m stamping the frame number into the mov file. The issue is my sequence starts at 1001 and using text=%n is that n is zero based. Can I offset this with my start_frame number ? or use another expression to pass the exr’s frame number to the text ?

  Z:\software\ffmpeg\ffmpeg.exe -start_number 1001 -gamma 2.2 -i P:/rnd/test/render/ballRender/ballRender_v01_%4d.exr -vf "drawtext=fontfile='C\:\\Windows\\Fonts\\arial.ttf': text=%{n} :fontsize=40: x=10: y=10: fontcolor=white: box=1: boxcolor=0x00000099" -r 24 -y P:/rnd/test/render/ballRender/ballRender_v01.mov

• android ffmpeg synchronize thread

  28 juin 2018, par Junburg

  I’m currently working on cutting and pasting audio with ffmpeg on Android. The problem is that when one audio file is not finished, there are other working files that need to be executed. I think the error below means this. I work through threads. An expression that executes a thread whenever there is a file to be processed.

  W/System.err: com.github.hiteshsondhi88.libffmpeg.exceptions.FFmpegCommandAlreadyRunningException: FFmpeg command is already running, you are only allowed to run single command at a time
  
  W/System.err:     at com.github.hiteshsondhi88.libffmpeg.FFmpeg.execute(FFmpeg.java:63)
  
                at com.github.hiteshsondhi88.libffmpeg.FFmpeg.execute(FFmpeg.java:89)
  
                at com.softcode.tablet.Mp3Concat_Thread$2.run(Mp3Concat_Thread.java:614)
  
                at java.lang.Thread.run(Thread.java:762)

  So what I want to ask is how to synchronize if a file comes in when the thread’s work is not over yet. Since the ffmpeg object is created with a singleton pattern, it seems that you will not be able to create a new object for each operation.

  If you know the answer, I would appreciate your reply.