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• Do avcodec_receive_frame and avcodec_send_packet block / how to design ffmpeg decoding loop ?

  12 octobre 2020, par Paprika

  I'm thinking about how to design a loop that reads frames from internet, feed to ffmpeg decoder and then receive from ffmpeg to send to a render.

  


  Take this pseudocode loop in consideration :

  


  while true {
    auto packet = receive_packet_from_network();
    avcodec_send_packet(packet);
    auto frame = alloc_empty_frame();
    int r = avcodec_receive_frame(&frame);
    if (r==0) {
        send_to_render(frame);
    }
}


  


  do avcodec_send_packet or avcodec_receive_frame block or ffmpeg has an internal thread ? I'm concerned about this loop because it waits for packets from network, so it has some delay. I'd like to do something like this instead :

  


  //thread 1
while true {
    auto packet = receive_packet_from_network();
    avcodec_send_packet(packet);
}
//thread 2
while true {
    auto frame = alloc_empty_frame();
    int r = avcodec_receive_frame(&frame);
    if (r==0) {
        send_to_render(frame);
    }
}


  


  however, now, if avcodec_receive_frame does not block, then this loop would run too fast, millions of times per second.

  


  So, how should I design the send/receive of packets in ffmpeg in the most efficient way ? I don't want to spend cpu cycles like in the thread2 loop.

  


• Google Speech API - Is there a way to determine if the audio has human voice or not ?

  20 décembre 2019, par stupid_sma

  I am making an audio filtering application at work that reads over hundreds of audio files and filters them. So, if the audio has human voice in it, it will accept it and if it does not- it will delete the audio file.

  I am using ffmpeg to get the details of the audio and add other filters like size and duration and silence (though it is not very accurate in detecting silence for all audio files.)

  My company asked me to try the Google Cloud Speech API to detect if the audio has any human voice in it.

  So with this code, some audio files return a Transcript of spoken words in the audio file, but what I need is to determine if a human is speaking or not.

  I have considered using hark.js for it but there does not seem to be enough documentation and I am short on time !

  Ps. I am an intern and I’m just starting out with programming. I apologize if my question does not make sense or sounds dumb.

     # Includes the autoloader for libraries installed with composer
  
     require __DIR__ . '/vendor/autoload.php';
  
  
  
     # Imports the Google Cloud client library
  
     use Google\Cloud\Speech\V1\SpeechClient;
  
     use Google\Cloud\Speech\V1\RecognitionAudio;
  
     use Google\Cloud\Speech\V1\RecognitionConfig;
  
     use Google\Cloud\Speech\V1\RecognitionConfig\AudioEncoding;
  
  
  
     putenv('GOOGLE_APPLICATION_CREDENTIALS=../../credentials.json');
  
  
  
  
  
  
  
     echo getcwd() . "<br />";
  
     chdir('test-sounds');
  
     echo getcwd() . "<br />";
  
     echo shell_exec('ls -lr');
  
  
  
     $fileList = glob('*');
  
     foreach($fileList as $filename){
  
     //echo $filename, '<br />';
  
  
  
     # The name of the audio file to transcribe
  
     $audioFile = __DIR__ . '/' . $filename;
  
  
  
     # get contents of a file into a string
  
     $content = file_get_contents($audioFile);
  
  
  
     # set string as audio content
  
     $audio = (new RecognitionAudio())
  
         ->setContent($content);
  
  
  
     # The audio file's encoding, sample rate and language
  
     $config = new RecognitionConfig([
  
         'encoding' => AudioEncoding::LINEAR16,
  
         'language_code' => 'ja-JP'
  
     ]);
  
  
  
     # Instantiates a client
  
     $client = new SpeechClient();
  
  
  
     # Detects speech in the audio file
  
     $response = $client->recognize($config, $audio);
  
  
  
     # Print most likely transcription
  
     foreach ($response->getResults() as $result) {
  
         $alternatives = $result->getAlternatives();
  
         $mostLikely = $alternatives[0];
  
         $transcript = $mostLikely->getTranscript();
  
         printf('<br />Transcript: %s' . PHP_EOL, $transcript . '<br />');
  
  
  
     }
  
  
  
     $client->close();
  
  
  
     }
  
  
  
     ?> ```

• Question about coding design of interface and receivers

  14 décembre 2018, par the_real_one

  I am trying to create an interface for an FFmpeg conversion scheme where :

  • New() should return whatever implements it
  • (receiver *interface) Convert() is the only method that should be implemented and the underlying details hidden (source files from : URL, File, etc.)

  How would I accomplish the above problem and design the code in such a way that you have various New() methods returning an FFmpegConverer that enforces the implementation of the Convert() method but with the underlying details behind each New() being different ? Or is that just a bad design to begin with ?

  My code may be less relevant than my problem statement but this is what I have so far which does not pass any go sanity checks :

  // FfmpegConverter is the interface for setting the public facing local
  
  // video files
  
  type FfmpegConverter interface {
  
    Convert() error
  
  }
  
  
  
  // localVideo holds the file information for a downloaded video
  
  type localVideo struct {
  
    inputAudioFile * os.File
  
    inputVideoFile * os.File
  
    outputVideoFile * os.File
  
  }
  
  
  
  // New initializes a new FfmpegConverter
  
  func New(inputVideoFilePath string, inputAudioFilePath string, outputVideoFilePath string)(ffmpegConverter FfmpegConverter, err error) {
  
    ffmpegConverter = & localVideo {}
  
  
  
    // Set input video file
  
    ffmpegConverter.inputVideoFile, err = os.Open(inputVideoFilePath)
  
    if err != nil {
  
      return
  
    }
  
    if err = ffmpegConverter.inputVideoFile.Close();
  
    err != nil {
  
      return
  
    }
  
  
  
    // Set input audio file
  
    ffmpegConverter.inputAudioFile, err = os.Open(inputAudioFilePath)
  
    if err != nil {
  
      return
  
    }
  
    if err = ffmpegConverter.inputAudioFile.Close();
  
    err != nil {
  
      return
  
    }
  
  
  
    // Set output video file
  
    ffmpegConverter.outputVideoFile, err = os.Create(outputVideoFilePath)
  
    if err != nil {
  
      return
  
    }
  
    if err = ffmpegConverter.outputVideoFile.Close();
  
    err != nil {
  
      return
  
    }
  
  
  
    return
  
  }
  
  
  
  // Convert will convert the input video and input audio files to an combined
  
  // output video file
  
  func(l * localVideo) Convert()(err error) {
  
    // Do stuff with the internal struct
  
    // ...
  
  }