Simplifies and improves code. Removes some duplication

src/main/java/net/knarcraft/ffmpegconverter/utility/FFMpegHelper.java

@@ -88,24 +88,149 @@ public final class FFMpegHelper {
     /**
      * Starts and prints output of a process
      *
-     * @param process <p>The process to run.</p>
-     * @param folder  <p>The folder the process should run in.</p>
+     * @param processBuilder <p>The process to run.</p>
+     * @param folder         <p>The folder the process should run in.</p>
+     * @param spacer         <p>The character(s) to use between each new line read.</p>
+     * @param write          <p>Whether to write the output directly instead of storing it.</p>
      * @throws IOException <p>If the process can't be readProcess.</p>
      */
-    public static void convertProcess(ProcessBuilder process, File folder) throws IOException {
+    public static String runProcess(ProcessBuilder processBuilder, File folder, String spacer, boolean write)
+            throws IOException {
+        //Give the user information about what's about to happen
         OutputUtil.print("Command to be run: ");
-        OutputUtil.println(process.command().toString());
-        process.directory(folder);
-        process.redirectErrorStream(true);
-        Process processConvert = process.start();
-        BufferedReader readerConvert = new BufferedReader(new InputStreamReader(processConvert.getInputStream()));
-        while (processConvert.isAlive()) {
-            String read = readProcess(readerConvert, "\n");
+        OutputUtil.println(processBuilder.command().toString());
+
+        //Set directory and error stream
+        processBuilder.directory(folder);
+        processBuilder.redirectErrorStream(true);
+
+        Process process = processBuilder.start();
+        BufferedReader processReader = new BufferedReader(new InputStreamReader(process.getInputStream()));
+        StringBuilder output = new StringBuilder();
+        while (process.isAlive()) {
+            String read = readProcess(processReader, spacer);
             if (!read.equals("")) {
-                OutputUtil.println(read);
+                if (write) {
+                    OutputUtil.print(read);
+                } else {
+                    output.append(read);
+                }
             }
         }
         OutputUtil.println("Process finished.");
+        return output.toString();
+    }
+
+    /**
+     * Adds audio to a command
+     *
+     * @param command     <p>The command to add audio to.</p>
+     * @param audioStream <p>The audio stream to be added.</p>
+     * @param toStereo    <p>Whether to convert the audio stream to stereo.</p>
+     */
+    public static void addAudioStreams(List<String> command, AudioStream audioStream, boolean toStereo) {
+        if (audioStream != null) {
+            command.add("-map");
+            command.add("0:" + audioStream.getAbsoluteIndex());
+            if (toStereo && audioStream.getChannels() > 2) {
+                command.add("-af");
+                command.add("pan=stereo|FL=FC+0.30*FL+0.30*BL|FR=FC+0.30*FR+0.30*BR");
+                //command.add("pan=stereo|FL < 1.0*FL + 0.707*FC + 0.707*BL|FR < 1.0*FR + 0.707*FC + 0.707*BR");
+            }
+        }
+    }
+
+    /**
+     * Adds subtitles and video mapping to a command
+     *
+     * @param command        <p>The list containing the rest of the command.</p>
+     * @param subtitleStream <p>The subtitle stream to be used.</p>
+     * @param videoStream    <p>The video stream to be used.</p>
+     * @param file           <p>The file to convert.</p>
+     */
+    public static void addSubtitlesAndVideo(List<String> command, SubtitleStream subtitleStream,
+                                            VideoStream videoStream, File file) {
+        //No appropriate subtitle was found. Just add the video stream.
+        if (subtitleStream == null) {
+            command.add("-map");
+            command.add(String.format("0:%d", videoStream.getAbsoluteIndex()));
+            return;
+        }
+
+        //Add the correct command arguments depending on the subtitle type
+        if (!subtitleStream.getIsImageSubtitle()) {
+            addSubtitle(command, subtitleStream, videoStream);
+        } else if (file.getName().equals(subtitleStream.getFile())) {
+            addInternalImageSubtitle(command, subtitleStream, videoStream);
+        } else {
+            addExternalImageSubtitle(command, subtitleStream, videoStream);
+        }
+    }
+
+    /**
+     * Adds subtitle commands to a command list
+     *
+     * @param command        <p>The list containing the FFmpeg commands.</p>
+     * @param subtitleStream <p>The subtitle stream to add.</p>
+     * @param videoStream    <p>The video stream to burn the subtitle into.</p>
+     */
+    private static void addSubtitle(List<String> command, SubtitleStream subtitleStream, VideoStream videoStream) {
+        command.add("-map");
+        command.add(String.format("0:%d", videoStream.getAbsoluteIndex()));
+        command.add("-vf");
+        String safeFileName = escapeSpecialCharactersInFileName(subtitleStream.getFile());
+        String subtitleCommand = String.format("subtitles='%s':si=%d", safeFileName,
+                subtitleStream.getRelativeIndex());
+        command.add(subtitleCommand);
+    }
+
+    /**
+     * Escapes special characters which can cause trouble for ffmpeg
+     *
+     * @param fileName <p>The filename to escape.</p>
+     * @return <p>A filename with known special characters escaped.</p>
+     */
+    private static String escapeSpecialCharactersInFileName(String fileName) {
+        return fileName.replaceAll("\\\\", "\\\\\\\\\\\\\\\\")
+                .replaceAll("'", "'\\\\\\\\\\\\\''")
+                .replaceAll("%", "\\\\\\\\\\\\%")
+                .replaceAll(":", "\\\\\\\\\\\\:")
+                .replace("]", "\\]")
+                .replace("[", "\\[");
+    }
+
+    /**
+     * Adds image subtitle commands to a command list
+     *
+     * @param command        <p>The list containing the FFmpeg commands.</p>
+     * @param subtitleStream <p>The subtitle stream to add.</p>
+     * @param videoStream    <p>The video stream to burn the subtitle into.</p>
+     */
+    private static void addInternalImageSubtitle(List<String> command, SubtitleStream subtitleStream,
+                                                 VideoStream videoStream) {
+        command.add("-filter_complex");
+        String filter = String.format("[0:v:%d][0:%d]overlay", videoStream.getAbsoluteIndex(),
+                subtitleStream.getAbsoluteIndex());
+        command.add(filter);
+    }
+
+    /**
+     * Adds external image subtitle commands to a command list
+     *
+     * @param command               <p>The list containing the FFmpeg commands.</p>
+     * @param externalImageSubtitle <p>The external image subtitle stream to add.</p>
+     * @param videoStream           <p>The video stream to burn the subtitle into.</p>
+     */
+    private static void addExternalImageSubtitle(List<String> command, SubtitleStream externalImageSubtitle,
+                                                 VideoStream videoStream) {
+        command.add("-i");
+        command.add(externalImageSubtitle.getFile());
+        command.add("-filter_complex");
+        command.add(String.format("[1:s]scale=width=%d:height=%d,crop=w=%d:h=%d:x=0:y=out_h[sub];[%d:v]" +
+                        "[sub]overlay", videoStream.getWidth(), videoStream.getHeight(), videoStream.getWidth(),
+                videoStream.getHeight(), videoStream.getAbsoluteIndex()));
+        command.add("-profile:v");
+        command.add("baseline");
     }
 
     /**
@@ -117,7 +242,7 @@ public final class FFMpegHelper {
      * @throws IOException <p>If something goes wrong while probing.</p>
      */
     private static String[] probeForStreams(String ffprobePath, File file) throws IOException {
-        ProcessBuilder builderProbe = new ProcessBuilder(
+        ProcessBuilder processBuilder = new ProcessBuilder(
                 ffprobePath,
                 "-v",
                 "error",
@@ -125,21 +250,8 @@ public final class FFMpegHelper {
                 "stream_tags=language,title:stream=index,codec_name,codec_type,channels,codec_type,width,height",
                 file.toString()
         );
-        OutputUtil.println();
-        OutputUtil.print("Probe command: ");
-        OutputUtil.println(builderProbe.command().toString());
-        builderProbe.redirectErrorStream(true);
-        Process processProbe = builderProbe.start();
-        BufferedReader readerProbe = new BufferedReader(new InputStreamReader(processProbe.getInputStream()));
-        StringBuilder output = new StringBuilder();
-        while (processProbe.isAlive()) {
-            String read = readProcess(readerProbe, PROBE_SPLIT_CHARACTER);
-            if (!read.equals("")) {
-                OutputUtil.printDebug(read);
-                output.append(read);
-            }
-        }
-        return StringUtil.stringBetween(output.toString(), "[STREAM]", "[/STREAM]");
+        String result = runProcess(processBuilder, file.getParentFile(), PROBE_SPLIT_CHARACTER, false);
+        return StringUtil.stringBetween(result, "[STREAM]", "[/STREAM]");
     }
 
     /**
@@ -180,19 +292,22 @@ public final class FFMpegHelper {
     private static List<StreamObject> getExternalSubtitles(String ffprobePath, File directory, String convertingFile)
             throws IOException {
         List<StreamObject> parsedStreams = new ArrayList<>();
+        //Find all files in the same directory with external subtitle formats
         String[] subtitleFormats = FileUtil.readFileLines("subtitle_formats.txt");
         File[] subtitleFiles = FileUtil.listFilesRecursive(directory, subtitleFormats, 1);
 
+        //Return early if no files were found
         if (subtitleFiles == null) {
             return parsedStreams;
         }
 
         String fileTitle = FileUtil.stripExtension(convertingFile);
         List<File> subtitleFilesList = new ArrayList<>(Arrays.asList(subtitleFiles));
-        //Finds the files which are subtitles belonging to the file
+        //Finds the files which are subtitles probably belonging to the file
         subtitleFilesList = ListUtil.getMatching(subtitleFilesList,
                 (subtitleFile) -> subtitleFile.getName().contains(fileTitle));
         for (File subtitleFile : subtitleFilesList) {
+            //Probe the files and add them to the result list
             String[] streams = probeForStreams(ffprobePath, subtitleFile);
             for (String stream : streams) {
                 String[] streamParts = stream.split(PROBE_SPLIT_CHARACTER);
@@ -291,7 +406,7 @@ public final class FFMpegHelper {
         String language = null;
         String title = "";
         for (String streamPart : streamParts) {
-            if (streamPart.contains("codec_name=")) {
+            if (streamPart.startsWith("codec_name=")) {
                 codecName = streamPart.replace("codec_name=", "");
             } else if (streamPart.startsWith("index=")) {
                 absoluteIndex = Integer.parseInt(streamPart.replace("index=", ""));