Sur d’autres sites (8687)

• Change Encoding of StandardInput.WriteLine

  25 avril 2018, par abdullah cinar

  I am trying to run ffmpeg executable using the Process to convert an input audio file to mp3 format. Below is the example call that works very well when I do it from the cmd.exe in Windows :

  "ffmpeg.dll -i "inputPath\input.wav" -vn -ar 44100 -ac 2 -ab 320k -f mp3 -y "outputPath\output.mp3"

  The input or output file paths can contain Turkish characters like ş ö ç ğ. So I have to take care of the encodings of StreamWriter.

  My snippet for the StreamWriter is :

  Process cmd = new Process();
  
  cmd.StartInfo.FileName = "cmd.exe";
  
  cmd.StartInfo.RedirectStandardInput = true;
  
  cmd.StartInfo.CreateNoWindow = false;
  
  cmd.StartInfo.UseShellExecute = false;
  
  cmd.Start();
  
  
  
  Encoding tr_encoding = Encoding.GetEncoding("iso-8859-9");
  
  
  
  using (StreamWriter sw = new StreamWriter(cmd.StandardInput.BaseStream, tr_encoding))
  
  {
  
      sw.WriteLine(ffmpeg_cmd + " & exit");
  
  }
  
  
  
  cmd.WaitForExit(); 

  But I always get No such file or directory error from the ffmpeg because the filepath contains a folder named as şşşş but my StreamWriter sends that folder name as ■■■.

  How to send command-line arguments in different arguments ?

• How to create a spectrogram image from an audio file in Python just like how FFMPEG does ?

  2 mai 2020, par hamandishe Mk

  My code :

  



  import matplotlib.pyplot as plt
from matplotlib.pyplot import specgram
import librosa
import librosa.display
import numpy as np
import io
from PIL import Image

samples, sample_rate = librosa.load('thabo.wav')
fig = plt.figure(figsize=[4, 4])
ax = fig.add_subplot(111)
ax.axes.get_xaxis().set_visible(False)
ax.axes.get_yaxis().set_visible(False)
ax.set_frame_on(False)
S = librosa.feature.melspectrogram(y=samples, sr=sample_rate)
librosa.display.specshow(librosa.power_to_db(S, ref=np.max))
buf = io.BytesIO()
plt.savefig(buf,  bbox_inches='tight',pad_inches=0)

# plt.close('all')
buf.seek(0)
im = Image.open(buf)
# im = Image.open(buf).convert('L')
im.show()
buf.close()


  



  Spectrogram produced

  



  

  



  Using FFMPEG

  



  ffmpeg -i thabo.wav -lavfi showspectrumpic=s=224x224:mode=separate:legend=disabled spectrogram.png

  



  Spectrogram produced

  



  

  



  Please help, i want a spectrogram that is exactly the same as the one produced by FFMPEG, for use with a speech recognition model exported from google's teachable machine.
Offline recognition

  


• Out-of-range channels being referenced when decoding AAC AUs

  3 février 2017, par SoxInCincy

  As part of a proprietary data stream, I have variable length AUs of raw AAC encoded data. The data is single channel and I have the configuration information on how the data was encoded. I need to decode this data to PCM for playback. Right now, I am trying to do so using ffmpeg’s libavcodec, but to no avail. The error I get from ffmpeg(libavcodec) when trying to decode is "channel element 3.7 is not allocated." As I am trying to decode single channel data, have the context set as single channel and channel layout of mono, I am not entirely sure why the decoder is looking for channels beyond 1.

  Can anyone point me in the right direction ? I appreciate any help !

  Prototype Code :

  //Initialize the decoder before sending AUs
  
  bool AAC_Decoder::initialize()
  
  {
  
      //register codecs
  
      avcodec_register_all();
  
      c=NULL;
  
      //attempt to find AAC decoder
  
      codec = avcodec_find_decoder(AV_CODEC_ID_AAC);
  
      if (codec==NULL)
  
      {
  
          std::cout<<"Could Not Find Codec"</setup codec context using known information about the stream
  
      c=avcodec_alloc_context3(codec);
  
      c->bit_rate=32000;
  
      c->channels=1;
  
      c->channel_layout=AV_CH_LAYOUT_MONO;
  
      c->sample_rate=16000;
  
  
  
      //attempt to open the codec using the prescribed context and no options
  
      if (avcodec_open2(c,codec,NULL)<0)
  
      {
  
          std::cout<<"Could Not Open Codec"</decode a single AU sent in a buffer
  
  bool AAC_Decoder::decode(uint8_t *sampleBuffer, uint32_t size)
  
  {
  
      //setup single AU packet
  
      AVPacket avPacket;
  
      av_init_packet(&avPacket);
  
      AVFrame * frame;
  
      pkt.size = size;
  
      pkt.data = sampleBuffer;
  
  
  
      //attempt to setup a frame
  
      frame = av_frame_alloc();
  
      if (!frame)
  
      {
  
          std::cout<<"Could not Allocate Frame"</attempt to decode the frame
  
      int gotFrame =0;
  
      int len = 0;
  
      len = avcodec_decode_audio4(c,frame,&gotFrame,&pkt);
  
  
  
      if (len < 0)//could not decode frame.  Currently getting -22 as response
  
      {
  
          std::cout<<"decoding error"</verify the frame was decoded.  
  
      {
  
          std::cout<<"don't have frame"</successfully decoded.  for now, cout the size as verification.
  
      {
  
          int data_size = av_samples_get_buffer_size(NULL, c->channels, frame->nb_samples, c->sample_fmt, 1);
  
          std::cout</free frame and return
  
      av_frame_free(&frame);
  
      return true;
  
  }