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• Insert Random silence multiple times between Audios in ffmpeg

  23 septembre 2021, par Gracie williams

  suppose I have MP3 of around 1 minute duration and increase its duration longer.Duration can be any.

  


  I want to randomly add N seconds of silence to that audio.

  


  I can generate the silence like below

  


  ffmpeg -f lavfi -i anullsrc=r=44100:cl=mono -t <seconds> -q:a 9 -acodec libmp3lame out.mp3&#xA;</seconds>

  


  And I can insert silence to audio like below

  


  ffmpeg -i in.wav -filter_complex "anullsrc,atrim=0:4[s];[0]atrim=0:14[a];[0]atrim=14,asetpts=N/SR/TB[b];[a][s][b]concat=3:v=0:a=1" out.wav


  


  Is there anyway to insert silence at multiple areas.With php I can generate random time to insert based on 60 seconds audio like below.

  


  $arr = [];
$arr[3] = 2; //here 3 is original audio insert time and 2 is the duration of silence
$arr[6] = 3;  //here 6 is original audio insert time and 3 is the duration of silence
$arr[10] = 1;
$arr[12] = 3;


  


  Now I want to insert silence between seconds based on above array like

  


  2 seconds silence at 3rd second
3 seconds silence at 6th second
1 second silence at 10th second


  


  and son on..

  


• Problem with processing FFMPEG video , the output video is totally black in first 3 seconds

  13 janvier 2021, par Trần Minh Tuấn

  I want to make a slideshow by using concat demuxer like this link :
https://trac.ffmpeg.org/wiki/Slideshow

  


  Here is the textfile preinputFiles.txt :

  


  file 'path a'
duration 2
file 'path b'
duration 2
file 'path c'
duration 2
file 'path c'


  


  and my command array is :

  


  String[] cmd = new String[]{
            "-f","concat","-i",
            textFile,
            "-vsync", "vfr", "-pix_fmt", "yuv420p",
            dest.getAbsolutePath()};


  


  the video has 3 seconds that it is totally black and run from 3s to 9s even the gallery shows that it is a 6 seconds long video .

  


  Thanks for the help !

  


• why ffmpeg frame to opengles texture is black

  5 juin 2012, par joe

  I'm trying to converted from a video using ffmpeg to an opengles texture in jni, but i just get a black texture. I have output the opengl with the glGetError(), there is any error.
  Here is my code :

  void*              pixels;    int err;
  
  int i;
  
  int frameFinished = 0;
  
  AVPacket packet;
  
  static struct SwsContext *img_convert_ctx;
  
  static struct SwsContext *scale_context = NULL;
  
  int64_t seek_target;
  
  
  
   int target_width = 320;
  
   int target_height = 240;
  
   GLenum error = GL_NO_ERROR;
  
   sws_freeContext(img_convert_ctx);  
  
  
  
  i = 0;
  
  while((i==0) && (av_read_frame(pFormatCtx, &packet)>=0)) {
  
      if(packet.stream_index==videoStream) {
  
          avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
  
  
  
          if(frameFinished) {
  
              LOGI("packet pts %llu", packet.pts);
  
              img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, 
  
                     pCodecCtx->pix_fmt, 
  
                     target_width, target_height, PIX_FMT_RGB24, SWS_BICUBIC, 
  
                     NULL, NULL, NULL);
  
              if(img_convert_ctx == NULL) {
  
                  LOGE("could not initialize conversion context\n");
  
                  return;
  
              }
  
              sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
  
              LOGI("sws_scale");
  
  
  
              videoTextures = new Texture*[1];
  
              videoTextures[0]->mWidth = 256; //(unsigned)pCodecCtx->width;
  
              videoTextures[0]->mHeight = 256; //(unsigned)pCodecCtx->height;
  
              videoTextures[0]->mData = pFrameRGB->data[0];
  
  
  
              glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
  
  
  
              glGenTextures(1, &(videoTextures[0]->mTextureID));
  
              glBindTexture(GL_TEXTURE_2D, videoTextures[0]->mTextureID);
  
              glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 
  
              glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
  
  
  
              if(0 == got_texture)
  
              {
  
                  glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, videoTextures[0]->mWidth, videoTextures[0]->mHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid *)videoTextures[0]->mData);
  
  
  
                  glTexSubImage2D(GL_TEXTURE_2D, 0, 0,0, videoTextures[0]->mWidth, videoTextures[0]->mHeight, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid *)videoTextures[0]->mData);
  
              }else
  
              {
  
                  glTexSubImage2D(GL_TEXTURE_2D, 0, 0,0, videoTextures[0]->mWidth, videoTextures[0]->mHeight, GL_RGBA, GL_UNSIGNED_BYTE, (GLvoid *)videoTextures[0]->mData);
  
  
  
              }
  
  
  
              i = 1;
  
              error = glGetError();
  
              if( error != GL_NO_ERROR ) {
  
                  LOGE("couldn't create texture!!");
  
                     switch (error) {
  
                      case GL_INVALID_ENUM:
  
                      LOGE("GL Error: Enum argument is out of range");
  
                      break;
  
                      case GL_INVALID_VALUE:
  
                          LOGE("GL Error: Numeric value is out of range");
  
                      break;
  
                      case GL_INVALID_OPERATION:
  
                          LOGE("GL Error: Operation illegal in current state");
  
                      break;
  
                      case GL_OUT_OF_MEMORY:
  
                          LOGE("GL Error: Not enough memory to execute command");
  
                      break;
  
                      default:
  
                          break;
  
                     }
  
              }
  
          }
  
      }
  
      av_free_packet(&packet);
  
  }

  i success to change pFrameRGB to a java bitmap， but i just want to change it to a texture in the c code,