if not re.match('.*matroska,webm,.*', infos, re.DOTALL):
        if re.match('.*, gif, from.*', infos, re.DOTALL):
            pipe = subprocess.Popen([ffmpeg_bin,
                              '-y',  # force overwrite
                              '-i', chunked_file.file.name,
                              '-f', 'webm',
                              '-c:v', 'libvpx',
                              '-crf', '12',
                              '-b:v', '500K',
                              chunked_file.file.name],  # output to original file
                              stdout=subprocess.PIPE,
                              stderr=subprocess.PIPE)

            pipe.wait()

            pipe = subprocess.Popen([ffmpeg_bin,
                                     '-i', chunked_file.file.name],
                                    stdout=subprocess.PIPE,
                                    stderr=subprocess.PIPE)

            pipe.stdout.readline()
            infos = pipe.stderr.read()
        else:
            return AjaxResponseError({'error': 'wrongformat'})