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• Add frame to video in specified position

  28 septembre 2015, par QUANGPHAT ĐINH

  I’m using Aforge libs to read and write video files (the libs is here : http://www.aforgenet.com/framework/features/ffmpeg.html).

  Now I want to export a specific frame to edit, then import it back to the video.

  I could export frame by frame but I don’t know how to add it back to the video in specific frame. what should i do now ?

• How to convert char buffer (with pcm audio data) to short buffer

  18 décembre 2012, par testCoder

  I have char pAudioBuffer buffer which i got from function ffmpeg :

  int len = avcodec_decode_audio3(av_codec_context,
  
              (int16_t *) pAudioBuffer, &out_size, &packet);

  I know that audio format is two bytes per sample, i need to convert every two bytes to short value, i have tried to use code snippet below, but i often got zero instead of short value :

  int shortBufIndex = 0;
  
  for (int i = 0; i < (out_size); i += 2) {
  
      char b1 = pAudioBuffer[i];
  
      char b2 = pAudioBuffer[i + 1];
  
      short sample = atoi(&b1) + atoi(&b2);
  
      shortBuffer[shortBufIndex] = sample;
  
      shortBufIndex++;
  
      LOGI("BUFFER_ITEM='%d'", sample);
  
  }

  What i'm doing wrong, how to convert every two bytes in char buffer to short and and back.

  UPDATE :

  system's byte order is LITTLE_ENDIAN i have test it like this : Endianness of Android NDK

  How can i convert every two bytes in buffer to sample of short type and back. Please can you provide any code sample.

  UPDATE

  I have tried to access to short as pairs, here is my fixed code, but it not work, i don't hear any sound :

      int shortBufIndex = 0;
  
      for (int i = 0; i < (out_size); i += 2) {
  
          char * byte = (char *) pAudioBuffer[i];
  
          short * sample = byte;
  
          shortBuffer[shortBufIndex] = sample;
  
  }

  What i'm doing wrong ?
  I need conversion like this : byte array to short array and back again in java but in c.

• unconnected output - FFMPEG

  9 avril 2018, par Hernan Quintero

  Im trying to make my first apple Service.

  I want FFMPEG to extract 5.1 Audio from a video with this command line :

  ffmpeg -i infile \
  
  -filter_complex "channelsplit=channel_layout=5.1[FL][FR][FC][LFE][BL] 
  
  [BR]" \
  
  -map "[FL]" front_left.wav \
  
  -map "[FR]" front_right.wav \
  
  -map "[FC]" front_center.wav \
  
  -map "[LFE]" lfe.wav \
  
  -map "[BL]" back_left.wav \
  
  -map "[BR]" back_right.wav

  It works very good from the Terminal, but when I try to make a Service in Automator I get the following error :

  Filter channelsplit:BR has an unconnected output

  This is the command line for the service :

  on run {input, parameters}
  
  tell application "Terminal"
  
      activate
  
      set filesString to ""
  
      repeat with file_ in input
  
          set filesString to filesString & " " & quoted form of (POSIX path of file_)
  
      end repeat
  
      do script "for f in" & filesString & "; do
  
  /usr/local/bin/ffmpeg -i \"$f\" -filter_complex 
  
  channelsplit=channel_layout=5.1[FL][FR][FC][LFE][BL][BR] 
  
  -map [FL] front_left.wav 
  
  -map [FR] front_right.wav 
  
  -map [FC] front_center.wav 
  
  -map [LFE] lfe.wav 
  
  -map [BL] back_left.wav 
  
  -map [BR] back_right.wav 
  
  done"
  
  end tell
  
  return input
  
  end run

  Could you guys help me to figure out what I’m doing wrong ?

  Thank you very much.