diff --git a/common/src/main/java/ctbrec/MpegUtil.java b/common/src/main/java/ctbrec/MpegUtil.java
index 3bb370be..b8a1b959 100644
--- a/common/src/main/java/ctbrec/MpegUtil.java
+++ b/common/src/main/java/ctbrec/MpegUtil.java
@@ -23,7 +23,7 @@ public class MpegUtil {
 
     private MpegUtil() {}
 
-    public static double getFileDuration(File file) throws IOException {
+    public static double getFileDurationInSecs(File file) throws IOException {
         try(FileChannelWrapper ch = NIOUtils.readableChannel(file)) {
             _2<Integer,Demuxer> m2tsDemuxer = createM2TSDemuxer(ch, TrackType.VIDEO);
             Demuxer demuxer = m2tsDemuxer.v1;
diff --git a/common/src/main/java/ctbrec/recorder/PlaylistGenerator.java b/common/src/main/java/ctbrec/recorder/PlaylistGenerator.java
index dd522d49..bfbc05a2 100644
--- a/common/src/main/java/ctbrec/recorder/PlaylistGenerator.java
+++ b/common/src/main/java/ctbrec/recorder/PlaylistGenerator.java
@@ -63,7 +63,7 @@ public class PlaylistGenerator {
             try {
                 float duration = 0;
                 if (file.getName().toLowerCase().endsWith(".ts")) {
-                    duration = (float) MpegUtil.getFileDuration(file);
+                    duration = (float) MpegUtil.getFileDurationInSecs(file);
                     if (duration <= 0) {
                         throw new InvalidTrackLengthException("Track has negative duration: " + file.getName());
                     }
diff --git a/common/src/main/java/ctbrec/recorder/download/VideoLengthDetector.java b/common/src/main/java/ctbrec/recorder/download/VideoLengthDetector.java
new file mode 100644
index 00000000..c06f0adc
--- /dev/null
+++ b/common/src/main/java/ctbrec/recorder/download/VideoLengthDetector.java
@@ -0,0 +1,75 @@
+package ctbrec.recorder.download;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.time.Duration;
+import java.util.Arrays;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import ctbrec.OS;
+import ctbrec.io.DevNull;
+import ctbrec.io.StreamRedirectThread;
+
+public class VideoLengthDetector {
+    private static final Logger LOG = LoggerFactory.getLogger(VideoLengthDetector.class);
+
+    /**
+     * Tries to determine the length of a video file by calling FFmpeg and parsing it's output
+     *
+     * @param videoFile
+     * @return the length as Duration object. The duration is negative, if the length couldn't be determined
+     */
+    public static Duration getLength(File videoFile) {
+        try {
+            String[] args = {
+                    "-hide_banner",
+                    "-i",
+                    videoFile.getCanonicalPath(),
+                    "-f",
+                    "ffmetadata",
+                    "-"
+            };
+            String[] cmdline = OS.getFFmpegCommand(args);
+            LOG.debug("Command line: {}", Arrays.toString(cmdline));
+            Process ffmpeg = Runtime.getRuntime().exec(cmdline, new String[0], videoFile.getParentFile());
+            int exitCode = 1;
+            ByteArrayOutputStream stdErrBuffer = new ByteArrayOutputStream();
+            Thread stdout = new Thread(new StreamRedirectThread(ffmpeg.getInputStream(), new DevNull()));
+            Thread stderr = new Thread(new StreamRedirectThread(ffmpeg.getErrorStream(), stdErrBuffer));
+            stdout.start();
+            stderr.start();
+            exitCode = ffmpeg.waitFor();
+            LOG.debug("FFmpeg exited with code {}", exitCode);
+            stdout.join();
+            stderr.join();
+            String ffmpegStderr = new String(stdErrBuffer.toByteArray());
+            return parseDuration(ffmpegStderr);
+        } catch (IOException | ProcessExitedUncleanException e) {
+            LOG.error("Error in FFMpeg thread", e);
+        } catch (InterruptedException e) {
+            Thread.currentThread().interrupt();
+            LOG.info("Interrupted while waiting for ffmpeg", e);
+        }
+        return Duration.ZERO.minusSeconds(1);
+    }
+
+    private static Duration parseDuration(String ffmpegStderr) {
+        Matcher m = Pattern.compile("Duration: (\\d{2}):(\\d{2}):(\\d{2}).(\\d{2}),").matcher(ffmpegStderr);
+        if (m.find()) {
+            int hours = Integer.parseInt(m.group(1));
+            int minutes = Integer.parseInt(m.group(2));
+            int seconds = Integer.parseInt(m.group(3));
+            int millis = Integer.parseInt(m.group(4));
+            return Duration.ofHours(hours)
+                    .plusMinutes(minutes)
+                    .plusSeconds(seconds)
+                    .plusMillis(millis);
+        }
+        return Duration.ofSeconds(-1);
+    }
+}
diff --git a/common/src/main/java/ctbrec/recorder/download/hls/HlsDownload.java b/common/src/main/java/ctbrec/recorder/download/hls/HlsDownload.java
index 1d2f034b..adca2dc2 100644
--- a/common/src/main/java/ctbrec/recorder/download/hls/HlsDownload.java
+++ b/common/src/main/java/ctbrec/recorder/download/hls/HlsDownload.java
@@ -348,7 +348,7 @@ public class HlsDownload extends AbstractHlsDownload {
         } catch (IOException | ParseException | PlaylistException e) {
             LOG.error("Couldn't determine recording length", e);
         }
-        return Duration.ofSeconds(0);
+        return Duration.ofSeconds(-1);
     }
 
     private double getPlaylistLength(File playlist) throws IOException, ParseException, PlaylistException {
diff --git a/common/src/main/java/ctbrec/recorder/download/hls/MergedFfmpegHlsDownload.java b/common/src/main/java/ctbrec/recorder/download/hls/MergedFfmpegHlsDownload.java
index a3d263cd..b86b0d55 100644
--- a/common/src/main/java/ctbrec/recorder/download/hls/MergedFfmpegHlsDownload.java
+++ b/common/src/main/java/ctbrec/recorder/download/hls/MergedFfmpegHlsDownload.java
@@ -44,6 +44,7 @@ import ctbrec.io.StreamRedirectThread;
 import ctbrec.recorder.ProgressListener;
 import ctbrec.recorder.download.HttpHeaderFactory;
 import ctbrec.recorder.download.ProcessExitedUncleanException;
+import ctbrec.recorder.download.VideoLengthDetector;
 import okhttp3.Request;
 import okhttp3.Request.Builder;
 import okhttp3.Response;
@@ -546,7 +547,11 @@ public class MergedFfmpegHlsDownload extends AbstractHlsDownload {
 
     @Override
     public Duration getLength() {
-        return Duration.between(getStartTime(), Instant.now());
+        try {
+            return VideoLengthDetector.getLength(targetFile);
+        } catch (Exception e) {
+            return Duration.between(getStartTime(), Instant.now());
+        }
     }
 
     @Override
diff --git a/common/src/main/java/ctbrec/recorder/postprocessing/DeleteTooShort.java b/common/src/main/java/ctbrec/recorder/postprocessing/DeleteTooShort.java
index bdf38b4f..5d2ed49b 100644
--- a/common/src/main/java/ctbrec/recorder/postprocessing/DeleteTooShort.java
+++ b/common/src/main/java/ctbrec/recorder/postprocessing/DeleteTooShort.java
@@ -25,7 +25,7 @@ public class DeleteTooShort extends AbstractPostProcessor {
         Duration minimumLengthInSeconds = Duration.ofSeconds(Integer.parseInt(getConfig().getOrDefault(MIN_LEN_IN_SECS, "0")));
         if (minimumLengthInSeconds.getSeconds() > 0) {
             Duration recordingLength = rec.getLength();
-            if (recordingLength.compareTo(minimumLengthInSeconds) < 0) {
+            if (!(recordingLength.isNegative() || recordingLength.isZero()) && recordingLength.compareTo(minimumLengthInSeconds) < 0) {
                 LOG.info("Deleting too short recording {} [{} < {}]", rec, recordingLength, minimumLengthInSeconds);
                 recordingManager.delete(rec);
             }