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• playback speed of ffmpeg-stitched python video plots

  30 juin 2012, par user1211129

  I've been generating videos out of plots made with matplotlib using a line of ffmpeg code. The output is in .mp4 format. However, when I tried to heighten the resolution of each individual plot to dpi=800, the resultant video (at 140 MB) lags severely when played back with quicktime. Is there a way around this ? I do wonder, if the file's too large to play efficiently, why does a movie of 6 GB play flawlessly ?

• php shell scripting for FFmpeg video conversion

  18 juillet 2012, par Subhransu

  I have a shell script for converting any video into mp4 format(using ffmpeg) . I want to write a php script for executing ffmpeg to convert any video format into mp4 video format .

  Here is the shell script : http://pastebin.com/PH3QWFqQ

  Shell script running good without shell_exec() .
  Update :

  I have tried doing it by using shell_exec() but i am getting an error :

  PHP Parse error : syntax error, unexpected T_STRING in test1.php on line 33

  UPDATE :

  I have tried with shell_exec() :
  It executes but not showing any output . But the .sh file alone shows output

• Wav File Encoding with FFMPEG

  7 septembre 2011, par user924702

  I want to convert raw PCM data(Taken from Android Phone mic) into a libGSM Wave file. After encoding into file, VLC player shows right codec information and duration but unable to play contents. Please help me to find what I am doing wrong.

  Below is my code for encoding and header writing :

  void EncodeTest(uint8_t *audioData, size_t audioSize)
  
  {
  
      AVCodecContext  *audioCodec;
  
      AVCodec *codec;
  
      uint8_t *buf;    int bufSize, frameBytes;
  
      __android_log_print(ANDROID_LOG_INFO, DEBUG_TAG,"Lets encode :%u with size %d\n",(int)audioData, (int)audioSize);
  
      //Set up audio encoder
  
      codec = avcodec_find_encoder(CODEC_ID_GSM);
  
      if (codec == NULL){
  
          __android_log_print(ANDROID_LOG_ERROR, DEBUG_TAG,"ERROR:: Unable to find encoder(CODEC_ID_GSM)");
  
          codec = avcodec_find_encoder(CODEC_ID_GSM);
  
          if (codec == NULL){
  
              __android_log_print(ANDROID_LOG_ERROR, DEBUG_TAG,"ERROR:: Unable to find encoder(CODEC_ID_GSM)");
  
              return;
  
          }
  
      }
  
      audioCodec                  = avcodec_alloc_context();
  
      audioCodec->channels        = 1;
  
      audioCodec->sample_rate     = 8000;
  
      audioCodec->sample_fmt      = SAMPLE_FMT_S16;
  
      audioCodec->bit_rate        = 13200;
  
      audioCodec->priv_data       = gsm_create();
  
  
  
      switch(audioCodec->codec_id) {
  
          case CODEC_ID_GSM:
  
              audioCodec->frame_size = GSM_FRAME_SIZE;
  
              audioCodec->block_align = GSM_BLOCK_SIZE;
  
              int one = 1;
  
              gsm_option(audioCodec->priv_data, GSM_OPT_WAV49, &one);
  
              break;
  
          case CODEC_ID_GSM_MS: {
  
              int one = 1;
  
              gsm_option(audioCodec->priv_data, GSM_OPT_WAV49, &one);
  
              audioCodec->frame_size = 2*GSM_FRAME_SIZE;
  
              audioCodec->block_align = GSM_MS_BLOCK_SIZE;
  
          }
  
      }
  
      audioCodec->coded_frame= avcodec_alloc_frame();
  
      audioCodec->coded_frame->key_frame= 1;
  
      audioCodec->time_base       = (AVRational){1,  audioCodec->sample_rate};
  
      audioCodec->codec_type      = CODEC_TYPE_AUDIO;
  
  
  
      if (avcodec_open(audioCodec, codec) < 0){
  
          __android_log_print(ANDROID_LOG_ERROR, DEBUG_TAG,"ERROR:: Unable to avcodec_open");
  
          return;
  
      }
  
  
  
      bufSize     = FF_MIN_BUFFER_SIZE * 10;
  
      buf         = (uint8_t *)malloc(bufSize);
  
      if (buf == NULL) return;
  
      frameBytes = audioCodec->frame_size * audioCodec->channels * 2;
  
      FILE *fileWrite = fopen(FILE_NAME,"w+b");
  
      if(NULL == fileWrite){
  
          __android_log_print(ANDROID_LOG_ERROR, DEBUG_TAG,"ERROR:: Unable to open file for reading.");
  
      }
  
      /*Write wave header*/
  
      WriteWav(fileWrite, 32505);/*Just for test*/
  
  
  
      /*Lets encode raw packet and write into file after header.*/
  
      __android_log_print(ANDROID_LOG_INFO, DEBUG_TAG,"Lets Encode Actual Bytes");
  
      int nChunckSize = 0;
  
      while (audioSize >= frameBytes)
  
      {
  
          int packetSize;
  
  
  
          packetSize = avcodec_encode_audio(audioCodec, buf, bufSize, (short *)audioData);
  
          __android_log_print(ANDROID_LOG_INFO, DEBUG_TAG,"Encoder returned %d bytes of data\n", packetSize);
  
          nChunckSize += packetSize;
  
          audioData += frameBytes;
  
          audioSize -= frameBytes;
  
          if(NULL != fileWrite){
  
              fwrite(buf, packetSize, 1, fileWrite);
  
          }
  
          else{
  
              __android_log_print(ANDROID_LOG_ERROR, DEBUG_TAG,"Unable to open file for writting... NULL");
  
          }
  
      }
  
      if(NULL != fileWrite){
  
          fclose(fileWrite);
  
      }
  
      __android_log_print(ANDROID_LOG_INFO, DEBUG_TAG,"----- Done with nChunckSize: %d --- ",nChunckSize);
  
       __android_log_print(ANDROID_LOG_INFO, DEBUG_TAG,"*****************************");
  
      wavReadnDisplayHeader(FILE_NAME);
  
      __android_log_print(ANDROID_LOG_INFO, DEBUG_TAG,"*****************************");
  
      wavReadnDisplayHeader("/sdcard/Voicemail2.wav");
  
  }

  Header Writing :

  /** Writes WAV headers */
  
  void WriteWav(FILE *f, long int bytes)
  
  {
  
      /* quick and dirty */
  
      fwrite("RIFF",sizeof(char),4,f);                /*  0-3 */      //RIFF
  
      PutNum(bytesã8,f,1,4);                       /*  4-7 */      //ChunkSize
  
      fwrite("WAVEfmt ",sizeof(char),8,f);            /*  8-15 */     //WAVE Header + FMT header
  
      PutNum(16,f,1,4);                               /* 16-19 */     //Size of the fmt chunk
  
      PutNum(49,f,1,2);                                /* 20-21 */     //Audio format, 49=libgsm wave, 1=PCM,6=mulaw,7=alaw, 257=IBM Mu-Law, 258=IBM A-Law, 259=ADPCM
  
      PutNum(1,f,1,2);                                /* 22-23 */     //Number of channels 1=Mono 2=Sterio
  
      PutNum(8000,f,1,4);                             /* 24-27 */     //Sampling Frequency in Hz 
  
      PutNum(2*8000,f,1,4);                           /* 28-31 */     //bytes per second /Sample/persec
  
      PutNum(2,f,1,2);                                /* 32-33 */     // 2=16-bit mono, 4=16-bit stereo 
  
      PutNum(16,f,1,2);                                /* 34-35 */     // Number of bits per sample
  
      fwrite("data",sizeof(char),4,f);                /* 36-39 */     
  
      PutNum(bytes,f,1,4);                            /* 40-43 */     //Sampled data length  
  
  }

  Please help....