Add normalized edit segment rendering

docs/cinematic-video-editing-service-plan.md

@@ -797,7 +797,7 @@ It writes the script only and requires an imported audio file.
 14. [x] Add project `inbox/` plan pickup.
 15. [x] Add strict JSON edit plan schema and validation.
 16. [x] Add `PUT /v1/edit-projects/{projectId}/plan`.
-17. [ ] Add simple segment rendering without transitions.
+17. [x] Add simple segment rendering without transitions.
 18. [ ] Add concat-based final timeline rendering.
 19. [ ] Add music and voiceover audio mixing.
 20. [ ] Add render manifest with command metadata and output details.

src/main/java/org/example/videoclips/editing/FfmpegEditRenderer.java

@@ -0,0 +1,113 @@
+package org.example.videoclips.editing;
+
+import org.example.videoclips.api.dto.EditProjectResponse;
+import org.example.videoclips.config.VideoClippingProperties;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.stereotype.Component;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+@Component
+@ConditionalOnProperty(name = "video-clipping.editing.enabled", havingValue = "true", matchIfMissing = true)
+public class FfmpegEditRenderer implements EditRenderer {
+
+    private final VideoClippingProperties.Editing properties;
+    private final EditProjectStore store;
+    private final EditProjectService projectService;
+    private final EditPlanValidator validator;
+    private final ProcessExecutor executor;
+
+    @Autowired
+    public FfmpegEditRenderer(VideoClippingProperties properties, EditProjectStore store,
+                              EditProjectService projectService, EditPlanValidator validator) {
+        this(properties, store, projectService, validator, FfmpegEditRenderer::execute);
+    }
+
+    FfmpegEditRenderer(VideoClippingProperties properties, EditProjectStore store,
+                       EditProjectService projectService, EditPlanValidator validator, ProcessExecutor executor) {
+        this.properties = properties.getEditing();
+        this.store = store;
+        this.projectService = projectService;
+        this.validator = validator;
+        this.executor = executor;
+    }
+
+    @Override
+    public void render(String projectId) {
+        EditPlan plan = validator.validate(projectId, store.readJson(projectId, "edit-plan.json", EditPlan.class));
+        EditProjectAnalysis analysis = store.readJson(projectId, "analysis.json", EditProjectAnalysis.class);
+        EditProjectResponse project = projectService.getProject(projectId);
+        projectService.updateProject(projectId, EditProjectStatus.RENDERING, Path.of(project.inputDirectory()), null);
+        Path work = store.projectDirectory(projectId).resolve("render-work");
+        createDirectory(work);
+        Map<String, ClipAnalysis> clips = analysis.clips().stream()
+                .collect(Collectors.toMap(ClipAnalysis::clipId, Function.identity()));
+        for (int index = 0; index < plan.decisions().size(); index++) {
+            EditDecision decision = plan.decisions().get(index);
+            Path output = work.resolve("segment_%04d.mp4".formatted(index + 1));
+            run(segmentCommand(clips.get(decision.clipId()).sourcePath(), decision, output));
+        }
+    }
+
+    List<String> segmentCommand(String source, EditDecision decision, Path output) {
+        String filter = "scale=%d:%d:force_original_aspect_ratio=decrease,".formatted(
+                properties.getOutputWidth(), properties.getOutputHeight())
+                + "pad=%d:%d:(ow-iw)/2:(oh-ih)/2,format=yuv420p".formatted(
+                properties.getOutputWidth(), properties.getOutputHeight());
+        List<String> command = new ArrayList<>(List.of(
+                properties.getFfmpegBinary(), "-hide_banner", "-y",
+                "-ss", Double.toString(decision.sourceStartSeconds()),
+                "-to", Double.toString(decision.sourceEndSeconds()),
+                "-i", source, "-vf", filter,
+                "-r", Integer.toString(properties.getOutputFrameRate()),
+                "-map", "0:v:0", "-map", "0:a?",
+                "-c:v", "libx264", "-preset", "veryfast", "-crf", "18",
+                "-c:a", "aac", "-b:a", properties.getAudioBitrate(),
+                "-ar", Integer.toString(properties.getAudioSampleRate()), output.toString()));
+        return List.copyOf(command);
+    }
+
+    private void createDirectory(Path directory) {
+        try {
+            Files.createDirectories(directory);
+        } catch (IOException ex) {
+            throw new IllegalStateException("Unable to create render working directory", ex);
+        }
+    }
+
+    private void run(List<String> command) {
+        try {
+            ProcessResult result = executor.execute(command);
+            if (result.exitCode() != 0) {
+                throw new IllegalStateException("FFmpeg edit render exited with code " + result.exitCode());
+            }
+        } catch (InterruptedException ex) {
+            Thread.currentThread().interrupt();
+            throw new IllegalStateException("Interrupted while rendering edit", ex);
+        } catch (IOException ex) {
+            throw new IllegalStateException("Unable to run FFmpeg edit render", ex);
+        }
+    }
+
+    private static ProcessResult execute(List<String> command) throws IOException, InterruptedException {
+        Process process = new ProcessBuilder(command).redirectErrorStream(true).start();
+        String output = new String(process.getInputStream().readAllBytes(), StandardCharsets.UTF_8);
+        return new ProcessResult(process.waitFor(), output);
+    }
+
+    record ProcessResult(int exitCode, String output) { }
+
+    @FunctionalInterface
+    interface ProcessExecutor {
+        ProcessResult execute(List<String> command) throws IOException, InterruptedException;
+    }
+}

src/test/java/org/example/videoclips/editing/FfmpegEditRendererTest.java

@@ -0,0 +1,29 @@
+package org.example.videoclips.editing;
+
+import org.example.videoclips.config.VideoClippingProperties;
+import org.junit.jupiter.api.Test;
+
+import java.nio.file.Path;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+class FfmpegEditRendererTest {
+
+    @Test
+    void buildsNormalizedSegmentCommand() {
+        VideoClippingProperties properties = new VideoClippingProperties();
+        FfmpegEditRenderer renderer = new FfmpegEditRenderer(properties, mock(EditProjectStore.class),
+                mock(EditProjectService.class), mock(EditPlanValidator.class), command -> null);
+        EditDecision decision = new EditDecision("clip-1", 1.25, 5.5, 0, 4.25,
+                "cut", "cut", 1, "grade", "reason");
+
+        var command = renderer.segmentCommand("source.mp4", decision, Path.of("segment.mp4"));
+
+        assertThat(command).containsSubsequence("-ss", "1.25", "-to", "5.5", "-i", "source.mp4");
+        assertThat(command).contains("scale=1920:1080:force_original_aspect_ratio=decrease,"
+                + "pad=1920:1080:(ow-iw)/2:(oh-ih)/2,format=yuv420p");
+        assertThat(command).containsSubsequence("-c:v", "libx264", "-c:a", "aac");
+        assertThat(command).endsWith("segment.mp4");
+    }
+}