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• 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); 
  
  }

• How to "re-interlace" a video ? How to convert a naïvely deinterlaced 480p video back to 480i ? [closed]

  8 juillet 2021, par toughluck

  I have a 480p video that was naïvely created from a 480i original and had no deinterlacing applied. The resulting format is 480p25. Combing is visible and I would like to convert it back to 480i50, so sort of "re-interlace" the video back to its original state.

  


  I have tried the solution from this question : How to convert a 1080p to 1080i using FFMPEG but it did not create the expected output.

  


  I looked at ffmpeg reference here : https://www.ffmpeg.org/ffmpeg-all.html but I could not find a proper option. Tons of filters to deinterlace interlaced videos but nothing to "re-interlace" them.

  


  My expected output would be this :

  


   ------> time
Input:
Frame 1 (0 ms)        Frame 2 (40 ms)

11111                 33333
22222                 44444
11111                 33333
22222                 44444

Output 1:
Frame 1 (0 ms)  Frame 2 (20 ms) Frame 3 (40 ms) Frame 4 (60 ms)
11111           22222           33333           44444
11111           22222           33333           44444
11111           22222           33333           44444
11111           22222           33333           44444

(Alternative) Output 2:
Frame 1 (0 ms)  Frame 2 (20 ms) Frame 3 (40 ms) Frame 4 (60 ms)
22222           11111           44444           33333
22222           11111           44444           33333
22222           11111           44444           33333
22222           11111           44444           33333


  


  (I'm not sure whether it's top field first or bottom field first, so I'd like to have an option to try both.)

  


  Is this possible ?

  


• Do i need a client to stream data ?

  28 novembre 2017, par Adalcar

  I am writing a web interface for a set of cameras using ffmpeg.

  The issue comes when trying to stream this data :
  after shamelessly ripping this code, replacing the ip with localhost for testing purposes, I tried to read the stream with VLC, to no avail : the server side runs without problem but the packets seem to disappear in thin air.

  That’s when I open the server with

  avio_open2(&server, "udp://localhost:554", AVIO_FLAG_WRITE, NULL, &options);

  If I use rtsp instead, it has the decency of failing with "unknown protocol" (?)

  and for http, it pops an unknown error.

  Do I need a client request to start streaming ?