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• FFMPEG : change sample rate/bit rate of a video with android-ndk

  9 avril 2013, par talhamalik22

  hi I am trying to change the sample rate of the audio streams of a video file using ffmpeg. but i am not able to change audio of the original file. Till now i am able to read audio and video streams separately and can show its sample rate. Don't know how can i apply this effect permanently. Following is my Java code.

   public class MainActivity extends Activity {
  
  public static native float logFileInfo(String inputfilename);
  
  static
  
  {
  
      System.loadLibrary("mylib");
  
  }
  
  
  
  
  
  @Override
  
  public void onCreate(Bundle savedInstanceState) {
  
      super.onCreate(savedInstanceState);
  
      TextView tv= new TextView(this);
  
      String path= Environment.getExternalStorageDirectory().getPath();
  
      path+="/test2_modified.mp4";
  
      float x=logFileInfo(path);
  
      String y=Float.toString(x);
  
      tv.setText(y);
  
      setContentView(tv);   
  
  }

  and my native file

  JNIEXPORT jfloat JNICALL Java_ru_dzakhov_ffmpeg_test_MainActivity_logFileInfo
  
          (JNIEnv * env,
  
       jobject this,
  
       jstring filename
  
      )
  
  {
  
  
  
  AVFormatContext *pFormatCtx;
  
  int             i, videoStream, audioStream;
  
  AVCodecContext  *pCodecCtx; 
  
  AVCodec         *pCodec;
  
  AVFrame         *pFrame; 
  
  AVPacket        packet;
  
  int             frameFinished;
  
  float           aspect_ratio;
  
  AVCodecContext  *aCodecCtx;
  
  AVCodec         *aCodec;
  
  
  
  
  
  av_register_all();
  
  char *str = (*env)->GetStringUTFChars(env, filename, 0);
  
   LOGI(str);
  
  // Open video file
  
  if(av_open_input_file(&pFormatCtx, str, NULL, 0, NULL)!=0)
  
      ;
  
  
  
  // Retrieve stream information
  
  if(av_find_stream_info(pFormatCtx)<0)
  
      ;
  
   LOGI("Separating");
  
  // Find the first video stream  
  
  videoStream=-1;
  
  audioStream=-1;
  
  for(i=0; inb_streams; i++) {
  
      if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO &&
  
          videoStream < 0) {
  
                      videoStream=i;
  
          }
  
      if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO &&
  
          audioStream < 0) {
  
                      audioStream=i;
  
          }
  
  }
  
  if(videoStream==-1)
  
       LOGI("Video stream is -1");    
  
  ;
  
  if(audioStream==-1)
  
       LOGI("Audio stream is -1");
  
          ;   
  
  
  
  //pFormatCtx->streams[audioStream]->codec->sample_rate=16000;
  
  aCodecCtx=pFormatCtx->streams[audioStream]->codec;
  
  //aCodecCtx->sample_rate=16000;
  
  jfloat sr=aCodecCtx->sample_rate;
  
  return sr;}

• Fluent-ffmpeg : Output with label 'screen0' doesnot exist in any diferent filter graph, or was already used elsewhere

  28 avril 2019, par mandaputtra

  I’m trying to take video frame by frame using fluent-ffmpeg, to create video masking and some kin of like experiment video editor. But when I do that by screenshots it says ffmpeg exited with code 1: Output with label 'screen0' does not exist in any defined filter graph, or was already used elsewhere.

  Here example array that I use for producing timestamps. ["0.019528","0.05226","0.102188","0.13635","0.152138","0.186013","0.236149" ...]

  // read json file that contains timestaps, array
  
  fs.readFile(`${config.videoProc}/timestamp/1.json`, 'utf8', async (err, data) => {
  
    if (err) throw new Error(err.message);
  
    const timestamp = JSON.parse(data);
  
    // screenshot happens here
  
    // loop till there is nothing on array...
  
    function takeFrame() {
  
      command.input(`${config.publicPath}/static/video/1.mp4`)
  
        .on('error', error => console.log(error.message))
  
        .on('end', () => {
  
          if (timestamp.length > 0) {
  
            // screenshot again ...
  
            takeFrame();
  
          } else {
  
            console.log('Process ended');
  
          }
  
        })
  
        .noAudio()
  
        .screenshots({
  
          timestamps: timestamp.splice(0, 100),
  
          filename: '%i.png',
  
          folder: '../video/img',
  
          size: '320x240',
  
        });
  
    }
  
    // call the function
  
    takeFrame();
  
  });

  My expected result are, I can genereta all the 600 screenshot. on one video. but the actual result is this error ffmpeg exited with code 1: Output with label 'screen0' does not exist in any defined filter graph, or was already used elsewhere and only 100 screen generated.

  [UPDATE]

  using -filter_complex as mentioned in here doenst work.

  ffmpeg exited with code 1: Error initializing complex filters.
  
  Invalid argument

  [UPDATE]

  command line arg :

  ffmpeg -ss 0.019528 -i D:\Latihan\video-cms-core\public/static/video/1.mp4 -y -filter_complex scale=w=320:h=240[size0];[size0]split=1[screen0] -an -vframes 1 -map [screen0] ..\video\img\1.png

• avcodec/dca : Unavpriv dca_sample_rates

  9 février 2021, par Andreas Rheinhardt

  avcodec/dca : Unavpriv dca_sample_rates
  Said table is 64 bytes long and exported so that it can be used both
  
  in libavcodec and libavformat. This commit stops doing so and instead
  
  duplicates it for shared builds, because the overhead of exporting the
  
  symbol is bigger than 64 bytes. It consists of the length of the name of
  
  the symbol (2x24 bytes), two entries in .dynsym (2x24 bytes), two
  
  entries for symbol version (2x2 bytes), one hash value in the exporting
  
  library (4 bytes) in addition to one entry in the importing library's
  
  .got and .rela.dyn (8 + 24 bytes).
  
  (The above numbers are for a Linux/GNU/Elf system ; the numbers for other
  
  platforms may be different.)
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/Makefile
  • [DH] libavcodec/dca.c
  • [DH] libavcodec/dca.h
  • [DH] libavcodec/dca_core.c
  • [DH] libavcodec/dca_parser.c
  • [DH] libavcodec/dca_sample_rate_tab.c
  • [DH] libavcodec/dca_sample_rate_tab.h
  • [DH] libavformat/Makefile
  • [DH] libavformat/dca_sample_rate_tab.c
  • [DH] libavformat/spdifenc.c