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• Fragmented MP4 has wrong duration in Windows Media Player

  3 février 2020, par Expressingx

  I’m streaming video from a camera to a file using ffmpeg. The case to use Fragmented MP4 is that there can be sudden power off and lose the video. I’ve configured the fragments to be at least 30 secs and this is how much the Windows Media Player reports for the duration even if its 2 hours long, after that it keeps streaming the video but is not seekable after the 30th second. How can be that fixed ?

  ffmpeg -c copy -movflags frag_keyframe+separate_moof+omit_tfhd_offset -min_frag_duration 30000000 -bsf:a aac_adtstoasc \ out.mp4

  If I use -movflags frag_keyframe+empty_moov then the video is not seekable at all and no duration reported.

  I aim for seekable video with correct duration both on VLC/Windows Media Player

  Version of ffmpeg : 3.3.4

• Error while running ffmpeg

  28 mars 2017, par user4543816

  I’m trying to convert a video file to images :
  ffmpeg -i XXXX.mp4 -r 1/1 $XX%03d.bmp

  and I get the following error

  video:121501kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead : unknown

  Any help will be appreciated

• SciPy and NumPy FFT calculation for multiple files failure

  28 mars 2016, par Noilladar

  The task is to convert the bunch of audio files (of different formats) from stereo to mono then find FFT for each one and save it to the .txt file
  The conversion is successfully made by calling ffmpeg as subprocess. Stereo files are deleted after mono files. The problem appears during the fft calculation : some files are done and the others are suddenly dismissed.
  Can it be thу library bug or I had omitted something about objects. It seems like the process cannot allocate or distribute memory or so. I appreciate any help ! Here is the entire code :

  # coding: cp1251
  
  import os
  
  import os.path
  
  import glob
  
  import subprocess
  
  import scipy
  
  from scipy.io.wavfile import read
  
  # from scipy.fftpack import fft (tried first with scipy then with numpy)
  
  from numpy.fft import fft
  
  
  
  
  
  TrackList = []
  
  ReadyNames = []
  
  
  
  FrameSize = 1024
  
  CurOffset = 0
  
  AudioLen = 0
  
  AudioFile = None
  
  InputData = None
  
  SampleRate = 44100.0
  
  
  
  SpecArray = []
  
  Freqs = []
  
  
  
  # ------ file processing and job organisation
  
  
  
  def NextAudioFrame():
  
      global CurOffset, AudioLen, AudioFile, FrameSize
  
      if (CurOffset + FrameSize) > AudioLen:
  
          r = None
  
      else:
  
          r = AudioFile[CurOffset:(CurOffset + FrameSize)]
  
          CurOffset += FrameSize
  
      return r
  
  
  
  def PrepareFrame(frm):
  
      a2 = range(FrameSize)
  
      for i in range(FrameSize):
  
          a2[i] = frm[i] / 32768.0
  
      mags = abs(fft(a2))
  
      return mags
  
  
  
  def SaveSpectrum(n):
  
      f = open(n + ".txt", "w")
  
      for i in range(FrameSize / 2):
  
          f.write(str(Freqs[i]) + "   " + str(SpecArray[i]) + "\n")
  
      f.close()
  
  
  
  
  
  def ReadTrackList():
  
      global TrackList, ReadyNames
  
      q = os.listdir(".")
  
      for i in q:
  
          t = os.path.splitext(i)
  
          if t[1] == ".txt":
  
              ReadyNames.append(t[0])
  
          elif t[1] != ".py":
  
              TrackList.append(i)
  
  
  
  
  
  def GenJustFileName(fn):
  
      q = len(fn) - 1
  
      z = ""
  
      while (q >= 0) and (z != "\\"):
  
          z = fn[q]
  
          q -= 1
  
      if (q >= 0) and (z == "\\"):
  
          t = fn[(q + 2):]
  
      else:
  
          t = fn
  
      w = t.find(".")
  
      return t[:w]
  
  
  
  
  
  def CheckFile(fn):
  
      r = True
  
      t = GenJustFileName(fn)
  
      for i in ReadyNames:
  
          if t == i:
  
              r = False
  
      return r
  
  
  
  def MakeFreqTable():
  
      global Freqs
  
      Freqs = []
  
      for i in range(FrameSize / 2):
  
          Freqs.append(i / (FrameSize / SampleRate))
  
  
  
  def MakeMonoMix(fn):
  
      mf = (os.path.splitext(fn)[0] + "_mono.wav")
  
      fm = subprocess.Popen(["ffmpeg", "-i", fn, "-ac", "1", "-ar", "44100", "-acodec", "pcm_s16le", mf])
  
      fm.wait()
  
  
  
  
  
  def GetSpectrumFromCurFile():
  
      global InputData, SampleRate, AudioFile, AudioLen, SpecArray, FrameSize, TempWavFile
  
      InputData = read(TempWavFile)
  
      SampleRate = InputData[0] * 1.0
  
      AudioFile = InputData[1]
  
      AudioLen = len(AudioFile)
  
      CurOffset = 0
  
  
  
      Cmpl = []
  
      SpecArray = range(FrameSize)
  
      for i in range(FrameSize):
  
          SpecArray[i] = 0.0
  
          Cmpl.append(0.0)
  
  
  
      frm_cnt = 0
  
      CurFrame = []
  
  
  
      while CurFrame != None:
  
          CurFrame = NextAudioFrame()
  
          if CurFrame != None:
  
              q = PrepareFrame(CurFrame)
  
              frm_cnt += 1
  
              for i in range(FrameSize):
  
                  Cmpl[i] += q[i]
  
  
  
      if frm_cnt > 0:
  
          for i in range(len(Cmpl)):
  
              SpecArray[i] = Cmpl[i] / frm_cnt
  
      print "Finished! Total frames processed " + str(frm_cnt) + "\n"
  
      return frm_cnt
  
  
  
  
  
  def ProcessFile1(fn):
  
      q = CheckFile(fn)
  
      if q == False:
  
          print "File not exists or already processed\n"
  
      else:
  
          MakeMonoMix(fn)
  
          print "\nProcessin file: " + fn + "\n"
  
          os.remove(fn)
  
  
  
  
  
  def ProcessFile2(fn):
  
      global TempWavFile
  
      print "\nProcessing file: " + fn + "\n"
  
      z = GenJustFileName(fn)
  
      TempWavFile = fn 
  
      f = GetSpectrumFromCurFile()
  
      if f > 0:
  
          ReadyNames.append(z)
  
          SaveSpectrum(z)
  
      os.remove(TempWavFile)          
  
  
  
  
  
  def InitJob():
  
      ReadTrackList()
  
      MakeFreqTable()
  
  
  
  InitJob()
  
  for i in TrackList:
  
      print GenJustFileName(i) + "\n"
  
      ProcessFile1(i)
  
  
  
  
  
  wlist = glob.glob("*.wav")
  
  
  
  for i in wlist:
  
      print GenJustFileName(i) + "\n"
  
      ProcessFile2(i)