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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;}

• How To Convert Bit Rate (VBR) Of MP3 File Using PHP ?

  29 avril 2014, par Dave

  Using php, I am trying to convert and overwrite an mp3 file using the following command....doesn’t work.

  ffmpeg -i /Users/MacBookPro/Desktop/dragons.mp3 -ar 44100 -ab 128k -f mp3 /Users/MacBookPro/Desktop/dragons.mp3

  So even when I try the command from the terminal, the new mp3 file is only about 5 seconds (originally 3 minutes). What am I doing wrong & any ideas on how to get the command working ?

  Thanks in advance !

• Error while opening encoder for output stream #0.1 - maybe incorrect parameters such as bit_rate, rate, width or height

  9 avril 2013, par Mahmoud Khafagy

  this is my command i exec() ffmpeg -i '1.mts' -deinterlace -ar 22050 -r 25 -qmin 3 -qmax 15 '1.flv' 2>&1

  and this is output

      Array
  
    (
  
      [0] => FFmpeg version SVN-r19795, Copyright (c) 2000-2009 Fabrice Bellard, et al.
  
      [1] =>   configuration: --enable-libmp3lame --enable-libvorbis --disable-mmx --enable-shared --prefix=/usr/ --enable-gpl
  
      [2] =>   libavutil     50. 3. 0 / 50. 3. 0
  
      [3] =>   libavcodec    52.35. 0 / 52.35. 0
  
      [4] =>   libavformat   52.38. 0 / 52.38. 0
  
      [5] =>   libavdevice   52. 2. 0 / 52. 2. 0
  
      [6] =>   libswscale     0. 7. 1 /  0. 7. 1
  
      [7] =>   built on Nov 29 2012 01:11:06, gcc: 4.1.2 20080704 (Red Hat 4.1.2-52)
  
      [8] => Input #0, mpegts, from '/home/gezgin99/public_html/app/webroot/uploads/entry/wrF15QJP6qgpuFI83MO0_1365508699.mts':
  
      [9] =>   Duration: 00:00:07.81, start: 1.000067, bitrate: 21934 kb/s
  
      [10] =>   Program 1
  
      [11] =>     Stream #0.0[0x1011]: Video: h264, yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 50 tbr, 90k tbn, 50 tbc
  
      [12] =>     Stream #0.1[0x1100]: Audio: ac3, 48000 Hz, 5.1, s16, 448 kb/s
  
      [13] =>     Stream #0.2[0x1200]: Subtitle: pgssub
  
      [14] => Output #0, flv, to '/home/gezgin99/public_html/app/webroot/uploads/entry/6A6PwqRI2aEdDwg2eHnf_1365508699.flv':
  
      [15] =>     Stream #0.0: Video: flv, yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], q=3-15, 200 kb/s, 90k tbn, 25 tbc
  
      [16] =>     Stream #0.1: Audio: libmp3lame, 22050 Hz, 5.1, s16, 64 kb/s
  
      [17] => Stream mapping:
  
      [18] =>   Stream #0.0 -> #0.0
  
      [19] =>   Stream #0.1 -> #0.1
  
      [20] => Error while opening encoder for output stream #0.1 - maybe incorrect parameters     such as bit_rate, rate, width or height
  
   )