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• OpenGL ES glReadPixels exc_bad_access

  6 décembre 2011, par Yanny

  I'm trying to create video from images using OpenGL ES and ffmpeg, but on iPad(4.3) I have a crash on glReadPixels

  -(NSData *) glToUIImage {
  
  
  
      int numberOfComponents = NUMBER_OF_COMPONENTS; //4
  
      int width = PICTURE_WIDTH; 
  
      int height = PICTURE_HEIGHT;
  
  
  
      NSInteger myDataLength = width * height * numberOfComponents;   
  
  
  
      NSMutableData * buffer= [NSMutableData dataWithLength :myDataLength];    
  
  
  
      [self checkForGLError]; 
  
  
  
      GLenum type = NUMBER_OF_COMPONENTS == 3 ? GL_RGB : GL_RGBA; //RGBA
  
      glReadPixels(0, 0, width, height, type, GL_UNSIGNED_BYTE, [buffer mutableBytes]);   //EXC_BAD_ACCESS here
  
  
  
      return buffer; 
  
  }

  It is working on iPhone 4 (4.3) and iPod Touch, but have problems on iPhone 3G(3.0) and iPad(4.3). Can you help me with this issue ?

  Also on iPhone 3G(3.0) and iPad(4.3) I have problems with Video - first 5-20 video frames have trash. Maybe issue with optimization ? Or architecture ?

  EDITED
  Stack :

  #0  0x33be3964 in void BlockNxN<64ul, 16ul, 1, BLOCK_CONVERTER_NULL_32>(unsigned long, int, int, unsigned long, int, int, unsigned int, unsigned int, unsigned int, unsigned int) ()
  
  #1  0x33be1c76 in glrBIFDetile ()
  
  #2  0x33b586b2 in sgxGetImage(SGXImageReadParams const*) ()
  
  #3  0x33b50d38 in gldReadPixels ()
  
  #4  0x31813e16 in glReadPixels_Exec ()
  
  #5  0x31e3c518 in glReadPixels ()

• Encoding SWF to video with Melt

  17 août 2015, par RocketR

  I’m doing a project which requires converting SWF movies to H.264 video on server-side, to be able to play them both in Flash player and on iPhone/iPad. And I really got stuck.

  I’m using Melt from http://www.mltframework.org/ and this is my command-line :

  melt movie.swf -consumer avformat:video.mp4 r=30 s=640x360 f=mp4 acodec=aac ab=128k ar=48000 vcodec=libx264 b=1000k an=1

  It does play in Flash player, but fails to play on iDevices. I googled for iPhone video requirements and it seems my video files do satisfy them(frame size, framerate and bitrate). What settings should I change to make it play ?

• Last subprocess call not working in concatenation code with FFMPEG. How should I go about fixing this ?

  28 novembre 2019, par S1mple

  clips = []
  
  
  
  #generates a list of mp4 files in a folder
  
  def clipFinder(CurrentDir, fileType):
  
      clips.clear()
  
      for r,d,f in os.walk(CurrentDir):
  
          for file in f:
  
              if fileType in file:
  
                  clips.append(r+file)
  
      random.shuffle(clips)
  
  
  
  #removes all files that have the string 'vod' in them as they cause problems during concatenation
  
  def removeVods(r):
  
      for f in clips:
  
          if 'vod' in clips:
  
              os.remove(r+f)
  
  
  
  #generates a string using the clips list to insert into the ffmpeg command
  
  def clipString():
  
      string = 'intermediate'
  
      clipList = []
  
      clipNum = 1
  
      for f in clips:
  
          clipList.append(string+str(clipNum)+'.ts'+'|')
  
          clipNum+=1
  
      string1 = ''.join(clipList)
  
      string2 = string1[0:len(string1)-1]
  
      return string2
  
  
  
  #concatenates the mp4 files in the clipString
  
  def concatFiles():
  
      clipFinder('***', '.mp4')
  
      removeVods('***')
  
      i = 0
  
      intermediates = []
  
      for f in clips:
  
          subprocess.call(['***', '-i', clips[i], '-c', 'copy', '-bsf:v', 'h264_mp4toannexb', '-f', 'mpegts', 'intermediate'+ str(i+1) +'.ts'])
  
          i += 1 
  
      clipsLength = len(clips)
  
      subprocess.call['***', '-i', '"concat:' + clipString() + '"', '-c', 'copy', '-bsf:a 
  
      aac_adtstoasc', 'output.mp4']

  I am trying to make a clip concatenator, but the last subprocess call won’t run and gives me no error. When I run the script the first FFmpeg call works fine and gives me my intermediate mp4 files, however, the second command, which works when I run it in terminal, does not work when I run it from python using subprocess.call.

  Problematic code :

  subprocess.call(['***', '-i', '"concat:' + clipString() + '"', '-c', 'copy', '-bsf:a aac_adtstoasc', 'output.mp4'])

  all places with * were paths such as : /davidscomputer/bin/ffmpeg/