Call ffmpeg using a 2pass encoding, to get the best quality and a guaranteed max file size

Author: MartelliEnrico

src/main/java/com/github/stickerifier/stickerify/media/MediaHelper.java

@@ -10,6 +10,7 @@
 import static com.github.stickerifier.stickerify.media.MediaConstraints.MAX_VIDEO_FILE_SIZE;
 import static com.github.stickerifier.stickerify.media.MediaConstraints.MAX_VIDEO_FRAMES;
 import static com.github.stickerifier.stickerify.media.MediaConstraints.VP9_CODEC;
+import static com.github.stickerifier.stickerify.process.ProcessHelper.IS_WINDOWS;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.github.stickerifier.stickerify.exception.CorruptedVideoException;
@@ -38,7 +39,9 @@
 import java.io.FileInputStream;
 import java.io.IOException;
 import java.nio.file.Files;
+import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Stream;
 import java.util.zip.GZIPInputStream;
 
 public final class MediaHelper {
@@ -52,7 +55,6 @@ public final class MediaHelper {
 
 	private static final Gson GSON = new Gson();
 	static final ProcessLocator FFMPEG_LOCATOR = new PathLocator();
-	private static final int PRESERVE_ASPECT_RATIO = -2;
 	private static final List<String> SUPPORTED_VIDEOS = List.of("image/gif", "video/quicktime", "video/webm",
 			"video/mp4", "video/x-m4v", "application/x-matroska", "video/x-msvideo");
 
@@ -333,42 +335,25 @@ private static void deleteFile(File file) throws FileOperationException {
 	 * @throws MediaException if file conversion is not successful
 	 */
 	private static File convertToWebm(File file) throws MediaException {
-		var mediaInfo = retrieveMultimediaInfo(file);
-
-		if (isVideoCompliant(file, mediaInfo)) {
+		if (isVideoCompliant(file)) {
 			LOGGER.atInfo().log("The video doesn't need conversion");
 
 			return null;
 		}
 
-		return convertWithFfmpeg(file, mediaInfo);
-	}
-
-	/**
-	 * Convenience method to retrieve multimedia information of a file.
-	 *
-	 * @param file the video to check
-	 * @return passed-in video's multimedia information
-	 * @throws CorruptedVideoException if an error occurred retrieving video information
-	 */
-	private static MultimediaInfo retrieveMultimediaInfo(File file) throws CorruptedVideoException {
-		try {
-			return new MultimediaObject(file, FFMPEG_LOCATOR).getInfo();
-		} catch (EncoderException e) {
-			throw new CorruptedVideoException("The video could not be processed successfully", e);
-		}
+		return convertWithFfmpeg(file);
 	}
 
 	/**
 	 * Checks if passed-in file is already compliant with Telegram's requisites.
 	 * If so, conversion won't take place and no file will be returned to the user.
 	 *
 	 * @param file the file to check
-	 * @param mediaInfo video's multimedia information
 	 * @return {@code true} if the file is compliant
 	 * @throws FileOperationException if an error occurred retrieving the size of the file
 	 */
-	private static boolean isVideoCompliant(File file, MultimediaInfo mediaInfo) throws FileOperationException {
+	private static boolean isVideoCompliant(File file) throws FileOperationException, CorruptedVideoException {
+		var mediaInfo = retrieveMultimediaInfo(file);
 		var videoInfo = mediaInfo.getVideo();
 		var videoSize = videoInfo.getSize();
 
@@ -382,63 +367,80 @@ private static boolean isVideoCompliant(File file, MultimediaInfo mediaInfo) thr
 				&& isFileSizeLowerThan(file, MAX_VIDEO_FILE_SIZE);
 	}
 
+	/**
+	 * Convenience method to retrieve multimedia information of a file.
+	 *
+	 * @param file the video to check
+	 * @return passed-in video's multimedia information
+	 * @throws CorruptedVideoException if an error occurred retrieving video information
+	 */
+	private static MultimediaInfo retrieveMultimediaInfo(File file) throws CorruptedVideoException {
+		try {
+			return new MultimediaObject(file, FFMPEG_LOCATOR).getInfo();
+		} catch (EncoderException e) {
+			throw new CorruptedVideoException("The video could not be processed successfully", e);
+		}
+	}
+
 	/**
 	 * Converts the passed-in file using FFmpeg applying Telegram's video stickers' constraints.
 	 *
 	 * @param file the file to convert
-	 * @param mediaInfo video's multimedia information
 	 * @return converted video
 	 * @throws MediaException if file conversion is not successful
 	 */
-	private static File convertWithFfmpeg(File file, MultimediaInfo mediaInfo) throws MediaException {
-		var webmVideo = createTempFile("webm");
-		var videoDetails = getResultingVideoDetails(mediaInfo);
-
-		var ffmpegCommand = new String[] {
+	private static File convertWithFfmpeg(File file) throws MediaException {
+		var logFile = createTempFile("log");
+		var baseFfmpegCommand = new String[] {
 				"ffmpeg",
+				"-y",
 				"-v", "error",
 				"-i", file.getAbsolutePath(),
-				"-vf", "scale=" + videoDetails.width() + ":" + videoDetails.height() + ",fps=" + videoDetails.frameRate(),
+				"-vf", "scale='if(gt(iw,ih),512,-2)':'if(gt(iw,ih),-2,512)',fps=min(30\\,source_fps)",
 				"-c:v", "libvpx-" + VP9_CODEC,
-				"-b:v", "256k",
-				"-crf", "32",
-				"-g", "60",
+				"-b:v", "650K",
+				"-pix_fmt", "yuv420p",
+				"-t", "3",
 				"-an",
-				"-t", videoDetails.duration(),
-				"-y", webmVideo.getAbsolutePath()
+				"-passlogfile", logFile.getAbsolutePath()
+		};
+
+		var pass1Options = new String[] {
+				"-pass", "1",
+				"-f", "webm",
+				IS_WINDOWS ? "NUL" : "/dev/null"
 		};
 
 		try {
-			ProcessHelper.executeCommand(ffmpegCommand);
+			var command = Stream.concat(Arrays.stream(baseFfmpegCommand), Arrays.stream(pass1Options))
+					.toArray(String[]::new);
+			ProcessHelper.executeCommand(command);
 		} catch (ProcessException e) {
-			deleteFile(webmVideo);
+			deleteFile(logFile);
 			throw new MediaException(e.getMessage());
 		}
 
-		return webmVideo;
-	}
-
-	/**
-	 * Convenience method to group resulting video's details,
-	 * calculated checking passed-in media info against Telegram's constraints.
-	 *
-	 * @param mediaInfo video's multimedia information
-	 * @return resulting video's details
-	 */
-	private static ResultingVideoDetails getResultingVideoDetails(MultimediaInfo mediaInfo) {
-		var videoInfo = mediaInfo.getVideo();
-		float frameRate = Math.min(videoInfo.getFrameRate(), MAX_VIDEO_FRAMES);
-		long duration = Math.min(mediaInfo.getDuration(), MAX_VIDEO_DURATION_MILLIS) / 1_000L;
+		var webmVideo = createTempFile("webm");
+		var pass2Options = new String[] {
+				"-pass", "2",
+				"-movflags", "+faststart",
+				webmVideo.getAbsolutePath()
+		};
 
-		boolean isWidthBigger = videoInfo.getSize().getWidth() >= videoInfo.getSize().getHeight();
-		int width = isWidthBigger ? MAX_SIDE_LENGTH : PRESERVE_ASPECT_RATIO;
-		int height = isWidthBigger ? PRESERVE_ASPECT_RATIO : MAX_SIDE_LENGTH;
+		try {
+			var command = Stream.concat(Arrays.stream(baseFfmpegCommand), Arrays.stream(pass2Options))
+					.toArray(String[]::new);
+			ProcessHelper.executeCommand(command);
+		} catch (ProcessException e) {
+			deleteFile(webmVideo);
+			throw new MediaException(e.getMessage());
+		} finally {
+			deleteFile(logFile);
+		}
 
-		return new ResultingVideoDetails(width, height, frameRate, String.valueOf(duration));
+		return webmVideo;
 	}
 
-	private record ResultingVideoDetails(int width, int height, float frameRate, String duration) {}
-
 	private MediaHelper() {
 		throw new UnsupportedOperationException();
 	}

src/main/java/com/github/stickerifier/stickerify/process/ProcessHelper.java

@@ -11,7 +11,7 @@
 
 public final class ProcessHelper {
 
-	static final boolean IS_WINDOWS = System.getProperty("os.name").toLowerCase().contains("windows");
+	public static final boolean IS_WINDOWS = System.getProperty("os.name").toLowerCase().contains("windows");
 	private static final int MAX_CONCURRENT_PROCESSES = IS_WINDOWS ? 4 : 5;
 	private static final Semaphore SEMAPHORE = new Semaphore(MAX_CONCURRENT_PROCESSES);
 

src/test/java/com/github/stickerifier/stickerify/media/MediaHelperTest.java

@@ -188,7 +188,7 @@ void resizeSmallWebmVideo() throws Exception {
 		var webmVideo = loadResource("small_video_sticker.webm");
 		var result = MediaHelper.convert(webmVideo);
 
-		assertVideoConsistency(result, 512, 212, 30F, 2_000L);
+		assertVideoConsistency(result, 512, 212, 30F, 2_600L);
 	}
 
 	@Test