remove head encoding in favour of no bugged streams

this leads to slightly inaccurate starts and ends

src/main/java/com/ddf/vodsystem/services/media/StreamActionsService.java

@@ -16,6 +16,7 @@ import java.util.Comparator;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 /**
@@ -131,37 +132,18 @@ public class StreamActionsService {
                     "trimOffset must be >= 0 and duration must be > 0 (got " + trimOffset + ", " + duration + ")"));
         }
 
-        Path headFragment = null;
-        Path concatList = null;
         try {
-            // Only the first segment is trimmed, so re-encode just that fragment and
+            String concatInput = "concat:" + segments.stream()
-            // stream-copy the rest. A zero offset means the first segment already
+                    .map(p -> p.toAbsolutePath().toString())
-            // starts at the requested point, so re-encoding it would be wasted work.
+                    .collect(Collectors.joining("|"));
-            List<Path> fragments;
-            if (trimOffset > 0) {
-                headFragment = Files.createTempFile("reencode-section-", ".ts");
-                encodeHead(segments.getFirst(), trimOffset, headFragment);
-
-                fragments = new ArrayList<>();
-                fragments.add(headFragment);
-                fragments.addAll(segments.subList(1, segments.size()));
-            } else {
-                fragments = segments;
-            }
-
-            // The concat demuxer (unlike the concat: byte protocol) rebases each
-            // fragment's timestamps to run continuously across the joins, absorbing
-            // the discontinuity between the PTS-0 head and the copied fragments.
-            concatList = writeConcatList(fragments);
 
             List<String> command = List.of(
                     "ffmpeg",
                     "-y",
-                    "-f", "concat",
+                    "-i", concatInput,
-                    "-safe", "0",
+                    "-t", String.valueOf(duration + trimOffset),
-                    "-i", concatList.toAbsolutePath().toString(),
-                    "-t", String.valueOf(duration),
                     "-c", "copy",
+                    "-avoid_negative_ts", "make_zero",
                     outputFile.toAbsolutePath().toString()
             );
 
@@ -180,9 +162,6 @@ public class StreamActionsService {
         } catch (RuntimeException e) {
             logger.error("Failed to save section to '{}': {}", outputFile, e.toString());
             return CompletableFuture.failedFuture(e);
-        } finally {
-            deleteTempQuietly(headFragment);
-            deleteTempQuietly(concatList);
         }
     }
 
@@ -257,52 +236,4 @@ public class StreamActionsService {
             throw new IOException("Failed to probe segment duration: " + segment, e);
         }
     }
-
-    private void encodeHead(Path firstSegment, float trimOffset, Path head)
-            throws IOException, InterruptedException {
-
-        List<String> command = List.of(
-                "ffmpeg",
-                "-y",
-                "-i", firstSegment.toAbsolutePath().toString(),
-                "-ss", String.valueOf(trimOffset),
-                "-c:v", "libx264",
-                "-preset", "veryfast",
-                "-crf", "20",
-                "-pix_fmt", "yuv420p",
-                "-c:a", "aac",
-                "-b:a", "160k",
-                "-muxdelay", "0",
-                "-muxpreload", "0",
-                "-f", "mpegts",
-                head.toAbsolutePath().toString()
-        );
-
-        logger.debug("Re-encoding head fragment '{}' from {}s", firstSegment, trimOffset);
-        commandRunner.run(command, line -> { /* head pass is short; no progress reporting */ });
-
-        if (!Files.exists(head) || Files.size(head) == 0) {
-            throw new IOException("Head re-encode produced no output — trimOffset " + trimOffset
-                    + "s may exceed the duration of " + firstSegment);
-        }
-    }
-
-    private Path writeConcatList(List<Path> fragments) throws IOException {
-        Path listFile = Files.createTempFile("concat-list-", ".txt");
-        List<String> lines = fragments.stream()
-                .map(p -> "file '" + p.toAbsolutePath().toString().replace("'", "'\\''") + "'")
-                .toList();
-        Files.write(listFile, lines);
-        return listFile;
-    }
-
-    private void deleteTempQuietly(Path tempFile) {
-        if (tempFile != null) {
-            try {
-                Files.deleteIfExists(tempFile);
-            } catch (IOException e) {
-                logger.warn("Failed to delete temp file '{}': {}", tempFile, e.toString());
-            }
-        }
-    }
 }