My media converter app crashes when handling file names with spaces - ffmpeg

Question

I wrote an app that uses ffmpeg to convert media files (.wav, .avi, .mp3, ... etc.). It works only with file names that have no spaces. When a file name with spaces is encountered, the app immediately closes. Can someone tell me if the string I'm using to call ffmpeg is correct, or need some characters escaped? Below is a fragment of the code:
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#Select Media
os.chdir("c:\\d-Converter\\ffmpeg\\bin")
wrkdir = os.getcwd()
filelist = os.listdir(wrkdir)
self.formats1 = []
for filename in filelist:
(head, filename) = os.path.split(filename)
if filename.endswith(".avi") or filename.endswith(".mp4") or filename.endswith(".flv") or filename.endswith(".mov") or filename.endswith(".mpeg4") or filename.endswith(".mpeg") or filename.endswith(".mpg2") or filename.endswith(".wav") or filename.endswith(".mp3"):
self.formats1.append(filename)
self.format_combo1=wx.ComboBox(panel, size=(140, -1),value='Select Media', choices=self.formats1, style=wx.CB_DROPDOWN, pos=(300,50))
self.Bind(wx.EVT_COMBOBOX, self.fileFormats, self.format_combo1)
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def fileFormats(self, e):
myFormats = {'audio': ('Select Format','.mp3', '.ogg', '.wav', '.wma'), 'video': ('Select Format','.flv','.mpg', '.mp4', '.mpeg')}
bad_file = ['Media not supported']
myFile = self.format_combo1.GetValue()
f_exten = (x for x in myFormats['audio'] + myFormats['video'] if myFile.endswith(x))
extension = f_exten.next()
if extension in myFormats['audio']:
self.format_combo2.SetItems(myFormats['audio'])
elif extension in myFormats['video']:
self.format_combo2.SetItems(myFormats['video'])
else:
self.format_combo2.SetItems(bad_file)
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def convertButton(self, e):
unit1 = self.format_combo1.GetValue()
if unit1:
unit1 = self.repl_Wspace(unit1)
#Media Formats
unit2 = self.format_combo2.GetValue()
unit3 = self.format_combo3.GetValue()
unit4 = None
unit5 = self.format_combo5.GetValue()
bitRate = self.format_combo6.GetValue()
unit6 = bitRate
if unit3 == '-qmax':
unit4 = self.format_combo4.GetValue()
else:
pass
os.chdir("c:\\d-Converter\\ffmpeg\\bin")
wrkdir = os.getcwd()
newfile = unit1
stripped = newfile.strip('mpeg3aviovfl4w2c.') #Strips the extension from the original file name
progname='c:\\d-Converter\\ffmpeg\\bin\\ffmpeg.exe' + ' -i '
preset1_a='-vn -ar 44100 -ac 2 -ab'
preset1_b='-f mp3 '
preset_mp3='.mp3'
chck_unit1 = self.my_endswith(unit1)
while True:
if unit5 == 'video to mp3':
if unit6 == 'k/bs' or unit6 == '':
amsg = wx.MessageDialog(None, 'You must select a bit rate.', 'Media Converter', wx.ICON_INFORMATION)
amsg.ShowModal()
amsg.Destroy()
break
elif unit5 == 'video to mp3' and unit6 != 'k/bs' or unit6 != '':
self.button.Disable()
self.button2.Enable()
self.format_combo1.Disable()
self.format_combo2.Disable()
self.format_combo3.Disable()
self.format_combo4.Disable()
self.format_combo5.Disable()
self.format_combo6.Disable()
startWorker(self.LongTaskDone, self.LongTask3, wargs=(progname, wrkdir, unit1, preset1_a, unit6, preset1_b, stripped, preset_mp3))
break
elif unit1 != unit1.endswith(".mpg") or unit1.endswith(".mpeg") or unit1.endswith(".avi") or unit1.endswith(".mp4") or unit1.endswith(".flv"):
bmsg = wx.MessageDialog(None, 'You must select a valid format to convert to .mp3.', 'Media Converter', wx.ICON_INFORMATION)
bmsg.ShowModal()
bmsg.Destroy()
break
else:
pass
if unit1 == 'Select Media' or unit1 == '':
amsg = wx.MessageDialog(None, 'You must select a media file!', 'Media Converter', wx.ICON_INFORMATION)
amsg.ShowModal()
amsg.Destroy()
break
elif unit2 == 'Select Format' or unit2 == '' or unit2 == chck_unit1:
amsg = wx.MessageDialog(None, 'You must select a valid format', 'Media Converter', wx.ICON_INFORMATION)
amsg.ShowModal()
amsg.Destroy()
break
elif unit3 == 'Select Quality' or unit3 == '':
amsg = wx.MessageDialog(None, 'You must select quality', 'Media Converter', wx.ICON_INFORMATION)
amsg.ShowModal()
amsg.Destroy()
break
elif unit3 != 'Select Quality' or unit3 != '':
self.format_combo5.Disable()
if unit3 == '-qmax':
if unit4 == '0' or unit4 == '':
amsg = wx.MessageDialog(None, 'You must select number between 1-8.', 'Media Converter', wx.ICON_INFORMATION)
amsg.ShowModal()
amsg.Destroy()
break
else:
self.button.Disable()
self.button2.Enable()
self.format_combo1.Disable()
self.format_combo2.Disable()
self.format_combo3.Disable()
self.format_combo4.Disable()
self.format_combo5.Disable()
startWorker(self.LongTaskDone, self.LongTask2, wargs=(progname,wrkdir,unit1,unit3,unit4,stripped,unit2))
break
elif unit3 == '-sameq':
self.button.Disable()
self.button2.Enable()
self.format_combo1.Disable()
self.format_combo2.Disable()
self.format_combo3.Disable()
self.format_combo4.Disable()
self.format_combo5.Disable()
startWorker(self.LongTaskDone, self.LongTask, wargs=(progname,wrkdir,unit1,unit3,stripped,unit2))
break
def LongTask(self, progname, wrkdir, unit1, unit3, stripped, unit2):
convert_file1 = progname + wrkdir + '\\' + unit1 + ' ' + unit3 + ' ' + stripped + unit2
self.statusbar.SetStatusText("Converting: " + unit1 + "...")
os.system(convert_file1)
print convert_file1
def LongTask2(self, progname, wrkdir, unit1, unit3, unit4, stripped, unit2):
convert_file2 = progname + wrkdir + '\\' + unit1 + ' ' + unit3 + ' ' + unit4 + ' ' + stripped + unit2
self.statusbar.SetStatusText("Converting: " + unit1 + "...")
os.system(convert_file2)
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Answer 1

Don't use os.system to execute your command. Instead, use subprocess, with each of your arguments as a separate entry in the arguments list:
import subprocess
progname='c:\\d-Converter\\ffmpeg\\bin\\ffmpeg.exe'
subprocess.check_call([progname, '-i', ... other args here])
This will ensure your arguments aren't interpreted incorrectly, and aren't susceptible to injection attacks.