def perform_command(self):
        """
        Perform command and return the appropriate exit code.

        :rtype: int
        """
        if len(self.actual_arguments) < 4:
            return self.print_help()
        text_format = gf.safe_unicode(self.actual_arguments[0])
        if text_format == u"list":
            text = gf.safe_unicode(self.actual_arguments[1])
        elif text_format in TextFileFormat.ALLOWED_VALUES:
            text = self.actual_arguments[1]
            if not self.check_input_file(text):
                return self.ERROR_EXIT_CODE
        else:
            return self.print_help()

        l1_id_regex = self.has_option_with_value(u"--l1-id-regex")
        l2_id_regex = self.has_option_with_value(u"--l2-id-regex")
        l3_id_regex = self.has_option_with_value(u"--l3-id-regex")
        id_regex = self.has_option_with_value(u"--id-regex")
        class_regex = self.has_option_with_value(u"--class-regex")
        sort = self.has_option_with_value(u"--sort")
        parameters = {
            gc.PPN_TASK_IS_TEXT_MUNPARSED_L1_ID_REGEX: l1_id_regex,
            gc.PPN_TASK_IS_TEXT_MUNPARSED_L2_ID_REGEX: l2_id_regex,
            gc.PPN_TASK_IS_TEXT_MUNPARSED_L3_ID_REGEX: l3_id_regex,
            gc.PPN_TASK_IS_TEXT_UNPARSED_CLASS_REGEX: class_regex,
            gc.PPN_TASK_IS_TEXT_UNPARSED_ID_REGEX: id_regex,
            gc.PPN_TASK_IS_TEXT_UNPARSED_ID_SORT: sort,
        }
        if (text_format == TextFileFormat.MUNPARSED) and ((l1_id_regex is None) or (l2_id_regex is None) or (l3_id_regex is None)):
            self.print_error(u"You must specify --l1-id-regex and --l2-id-regex and --l3-id-regex for munparsed format")
            return self.ERROR_EXIT_CODE
        if (text_format == TextFileFormat.UNPARSED) and (id_regex is None) and (class_regex is None):
            self.print_error(u"You must specify --id-regex and/or --class-regex for unparsed format")
            return self.ERROR_EXIT_CODE

        language = gf.safe_unicode(self.actual_arguments[2])

        audio_file_path = self.actual_arguments[3]
        if not self.check_input_file(audio_file_path):
            return self.ERROR_EXIT_CODE

        text_file = self.get_text_file(text_format, text, parameters)
        if text_file is None:
            self.print_error(u"Unable to build a TextFile from the given parameters")
            return self.ERROR_EXIT_CODE
        elif len(text_file) == 0:
            self.print_error(u"No text fragments found")
            return self.ERROR_EXIT_CODE
        text_file.set_language(language)
        self.print_info(u"Read input text with %d fragments" % (len(text_file)))

        self.print_info(u"Reading audio...")
        try:
            audio_file_mfcc = AudioFileMFCC(audio_file_path, rconf=self.rconf, logger=self.logger)
        except AudioFileConverterError:
            self.print_error(u"Unable to call the ffmpeg executable '%s'" % (self.rconf[RuntimeConfiguration.FFMPEG_PATH]))
            self.print_error(u"Make sure the path to ffmpeg is correct")
            return self.ERROR_EXIT_CODE
        except (AudioFileUnsupportedFormatError, AudioFileNotInitializedError):
            self.print_error(u"Cannot read file '%s'" % (audio_file_path))
            self.print_error(u"Check that its format is supported by ffmpeg")
            return self.ERROR_EXIT_CODE
        except Exception as exc:
            self.print_error(u"An unexpected error occurred while reading the audio file:")
            self.print_error(u"%s" % exc)
            return self.ERROR_EXIT_CODE
        self.print_info(u"Reading audio... done")

        self.print_info(u"Running VAD...")
        audio_file_mfcc.run_vad()
        self.print_info(u"Running VAD... done")

        min_head = gf.safe_float(self.has_option_with_value(u"--min-head"), None)
        max_head = gf.safe_float(self.has_option_with_value(u"--max-head"), None)
        min_tail = gf.safe_float(self.has_option_with_value(u"--min-tail"), None)
        max_tail = gf.safe_float(self.has_option_with_value(u"--max-tail"), None)

        self.print_info(u"Detecting audio interval...")
        start_detector = SD(audio_file_mfcc, text_file, rconf=self.rconf, logger=self.logger)
        start, end = start_detector.detect_interval(min_head, max_head, min_tail, max_tail)
        self.print_info(u"Detecting audio interval... done")

        self.print_result(audio_file_mfcc.audio_length, start, end)
        return self.NO_ERROR_EXIT_CODE
Perform command and return the appropriate exit code.

        :rtype: int