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• List Directory of files to text file sorted by creation date but don't show creation creation date in file

  25 mars 2019, par Oli Shingfield

  I’ve been doing some research on this problem but I can’t get my head around it to suit my particular issue.

  I would like to create a text file of a list of files in a directory, sorted by date but I don’t want the date to be shown in the file.
  The code I have so far is :

  #create list of clips to merge
  
  save_path = 'downloads/'
  
  ignored = 'test.bat','mergeclips.bat','draw.bat'
  
  onlyfiles = [f for f in listdir('downloads/') if isfile(join('downloads/', f)) if f not in ignored]
  
  
  
  with open('downloads/clipstomerge.txt', 'w') as f:
  
      for item in onlyfiles:
  
          f.write("file '%s'\n" % item )

  This code ignores the bat files but lists everything else out to a text file in a format ready for ffmpeg to merge the clips. The format of the text file looks like this :

  file 'ARandomClipName.mov'
  
  file 'Butterflies.mov'
  
  file 'Chickens.mov'

  At the moment the files are sorted alphabetically but I would like it to be sorted by creation date.
  Does anyone have any ideas how I could modify my code to fix my problem ?

• What ffmpeg command to use to convert a list of unsigned integers into an audio file ?

  21 mars 2019, par John

  I have a file that contains a list of about forty thousand integers that are space delimited, with each integer between the value of 0 and 255. It is this file here :

  https://github.com/johnlai2004/sound-project/blob/master/integers.txt

  If you connect a speaker to an ESP32 breakout board, then run this list of integers through the digital to analog converter at a frequency of 24kHz, you will hear the sentence, "That’s not the post that you missed."

  What I want to know is how do you use FFMPEG to convert this list of integers into a sound file that other computer can play to hear the same phrase ? I tried this command :

  ffmpeg -f u8 -ac 1 -ar 24000 -i integers.txt -y audio.wav

  But my audio.wav just sounds like white noise. I tried a few other values for -f and for -ar, but all I hear are different frequencies of white noise and maybe some extra buzzing.

  Is it possible to use ffmpeg to translate my list of integers into an audio file for other computers to play ? If so, what’s the correct ffmpeg command to do this ?

  OTHER NOTES

  If it helps, this is the sketch file that I upload to an ESP32 if I want to hear the audio :

  https://github.com/johnlai2004/sound-project/blob/master/play-audio.ino

  In short, the file looks like this :

  #define speakerPin 25                          //The pins to output audio on. (9,10 on UNO,Nano)
  
  #define bufferTotal 1347
  
  #define buffSize 32
  
  
  
  byte buffer[bufferTotal][buffSize];
  
  int buffItemN = 0;
  
  int bufferN = 0;
  
  
  
  hw_timer_t * timer = NULL;
  
  portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED;
  
  
  
  void IRAM_ATTR onTimer() {
  
    portENTER_CRITICAL_ISR(&timerMux);
  
  
  
  
  
    byte v = buffer[bufferN][buffItemN];
  
    dacWrite(speakerPin,v);
  
  
  
    buffItemN++;
  
  
  
    if(buffItemN >= buffSize){                                      //If the buffer is empty, do the following
  
      buffItemN = 0;                                              //Reset the sample count
  
      bufferN++;
  
      if(bufferN >= bufferTotal)
  
        bufferN = 0;
  
    }
  
  
  
    portEXIT_CRITICAL_ISR(&timerMux);
  
  
  
  }
  
  
  
  void setup() {      
  
  
  
  /* buffer records */
  
  buffer[0][0]=88;  // I split the long list of integers and load it into a 2D array
  
  buffer[0][1]=88;
  
  buffer[0][2]=86;
  
  buffer[0][3]=85;
  
  //etc....
  
  buffer[1346][28]=94;
  
  buffer[1346][29]=92;
  
  buffer[1346][30]=92;
  
  buffer[1346][31]=95;
  
  
  
  
  
  /* end buffer records */
  
  
  
    timer = timerBegin(0, 80, true);
  
    timerAttachInterrupt(timer, &onTimer, true);
  
    timerAlarmWrite(timer, 41, true);
  
    timerAlarmEnable(timer);
  
  
  
  }
  
  
  
  void loop() {
  
  
  
  }

  The buffer... is the list of integers found in the integers.txt file.

• How do I get ffmpeg to concat 1 second from a list of files ?

  13 juin 2023, par Stephen Fluin

  I have about a thousand video clips and I've got ffmpeg and an ffmpeg file list setup like this :

  



  file /path/to/1.mp4
file /path/to/2.mp4
...
file /path/to/1000.mp4


  



  I want to concatenate the first second of each clip into an output clip. I've experimented with duration and outpoints specified in the file list, but neither seems to do what I want.

  



  Here's the documentation I've read which I found unclear and lacking an example using the full API : https://ffmpeg.org/ffmpeg-formats.html#concat

  



  Here's the closest I've come (concat the entirety of all files at 100x speed) :

  



  ffmpeg -f concat -safe 0 -i ~/glass-videos.ffmpeg.txt -filter:v "setpts=PTS/100" -an output.mp4