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• How compress images with ffmpeg till specific size threshold , and ability to restore back

  20 mars 2019, par VitalyT

  I need to reduce as much storage as i can.

  so , Lets say i have dir in file system that contains pictures (png/jpeg ,etc...) and html ,js files

  My purpose is look for media
  filenames suffix for example *.jpg, *.png, *.webm, *.ico in a folder and
  compress max till 38K.

  basically the average original images size is 170K.

  Avatar images should be under 4KB when a good size would be 2KB

  I’ve tried so far

  ffmpeg -i ~/Desktop/test123.jpeg -vframes 1 -compression_level 100  ~/Desktop/output_1623x1623.png

  but it gives me maximum 104K...

  what is the best way to compress or scaling down the images but with ability to restore with the same quality

  regards,

• Can I add photon to video and make this photo to be thumbnails(Cover) ? [duplicate]

  2 avril 2019, par 林炳河

  This question already has an answer here :

  • How to add custom thumbnail to a .mp4 file using ffmpeg
    
    1 answer
    

  I want to add thumbnail to a video, but all of my attempts have been not working.

  I already try use ffmpeg command to do this, but it didn’t help.

  what command i used :

  ffmpeg -i source.mp4 -i cover.png  -filter_complex "[1:v]scale=720:1280[oval],[0:v][oval]overlay=enable='between(n,0,1)',fps=fps=15" -pix_fmt yuv420p -c:a copy output.mp4

  Please help me.

• Audio playing back at the wrong speed using FFmpeg on Android

  11 avril 2019, par Kyborg2011

  General problem in the following :
  I decode the audio as follows :

  ReSampleContext* rsc = av_audio_resample_init(
  
          1, aCodecCtx->channels,
  
          aCodecCtx->sample_rate, aCodecCtx->sample_rate,
  
          av_get_sample_fmt("u8"), aCodecCtx->sample_fmt,
  
          16, 10, 0, 1);
  
  
  
  while (av_read_frame(pFormatCtx, &packet)>= 0) {
  
      if (aCodecCtx->codec_type == AVMEDIA_TYPE_AUDIO) {
  
          int data_size = AVCODEC_MAX_AUDIO_FRAME_SIZE * 2;
  
          int size=packet.size;
  
          int decoded = 0;
  
  
  
           while(size > 0) {
  
               int len = avcodec_decode_audio3(aCodecCtx, pAudioBuffer, 
  
                   &data_size, &packet);
  
  
  
               //Сonvert audio to sample 8bit
  
               out_size = audio_resample(rsc, outBuffer, pAudioBuffer, len);
  
  
  
               jbyte *bytes = (*env)->GetByteArrayElements(env, array, NULL);
  
  
  
               memcpy(bytes, outBuffer, out_size);
  
               (*env)->ReleaseByteArrayElements(env, array, bytes, 0);
  
               (*env)->CallStaticVoidMethod(env, cls, mid, array, out_size, number);
  
  
  
               size -= len;
  
               number++;
  
           }
  
       }
  
   }

  Next release it AudioTrack. After that, I hear that song that was necessary, but with noise and speed of 2 times larger. In what may be the problem ?

  UPDATE :
  This is Java code :

  public static AudioTrack track;
  
  public static byte[] bytes;
  
  protected void onCreate(Bundle savedInstanceState) {
  
      super.onCreate(savedInstanceState);
  
      setContentView(R.layout.main);
  
      int bufSize = 2048;
  
      track = new AudioTrack(AudioManager.STREAM_MUSIC, 44100, AudioFormat.CHANNEL_OUT_MONO, 
  
                  AudioFormat.ENCODING_PCM_8BIT, bufSize, AudioTrack.MODE_STREAM); 
  
  
  
      bytes = new byte[bufSize];
  
      Thread mAudioThread = new Thread(new Runnable() {
  
          public void run() {
  
              int res = main(2, "/sdcard/muzika_iz_reklami_bmw_5_series_-_bmw_5_series.mp3", bytes);
  
              System.out.println(res);
  
          } 
  
      });
  
      mAudioThread.setPriority(Thread.MAX_PRIORITY);
  
      mAudioThread.start(); 
  
  }
  
  
  
  private static void play(byte[] play, int length, int p) {
  
      if (p==0){
  
          track.play();
  
      }
  
      track.write(play, 0, length); 
  
  }