improve support for input videos with no audio track

docs/jvc_js.md

@@ -67,6 +67,9 @@ Ratio of width / height (video or image).
 #### `samplingRate`
 Sampling rate in Hz (audio).
 
+#### `channelLayout`
+Channel layout (audio).
+
 #### `tracks`
 An array of the A/V tracks in a video. Only includes audio and video tracks.
 

src/main/java/jvc/model/JStreamType.java

@@ -18,7 +18,7 @@ public enum JStreamType {
     mkv        (".mkv",  video),
     mp3        (".mp3",  audio),
     mpeg_audio (".mp3",  audio),
-    aac        (".aac",  audio),
+    aac        (".m4a",  audio),
     flac       (".flac", audio),
     png        (".png",  image),
     jpg        (".jpg",  image),

src/main/java/jvc/model/info/JTrack.java

@@ -45,7 +45,11 @@ public class JTrack {
 
     public String channelLayout () {
         if (!empty(channelLayout)) {
-            return channelLayout.equals("L R") ? "stereo": channelLayout;
+            return channelLayout.equals("L R")
+                    ? "stereo"
+                    : channelLayout.equals("C")
+                    ? "mono"
+                    : channelLayout;
         }
         if (!empty(channels)) {
             if (isOnlyDigits(channels)) {

src/main/java/jvc/model/js/JAssetJs.java

@@ -20,6 +20,7 @@ public class JAssetJs {
     @Getter public final Integer width;
     @Getter public final Integer height;
     @Getter public final Double aspectRatio;
+    @Getter public final String channelLayout;
     @Getter public final Integer samplingRate;
     @Getter public JTrackJs[] allTracks = EMPTY_TRACKS;
     @Getter public JTrackJs[] tracks = EMPTY_TRACKS;
@@ -42,6 +43,7 @@ public class JAssetJs {
         this.height = h == null ? null : h.intValue();
 
         this.aspectRatio = asset.aspectRatio() == null ? Double.NaN : asset.aspectRatio().doubleValue();
+        this.channelLayout = asset.hasChannelLayout() ? asset.channelLayout() : null;
         this.samplingRate = asset.hasSamplingRate() ? asset.samplingRate().intValue() : 0;
 
         if (asset.hasInfo()) {

src/main/java/jvc/operation/exec/ExecBase.java

@@ -78,6 +78,7 @@ public abstract class ExecBase<OP extends JOperation> {
             System.out.println(script);
             return "";
         } else {
+            log.info("exec: "+script);
             return execScript(script);
         }
     }

src/main/java/jvc/operation/exec/MergeAudioExec.java

@@ -27,21 +27,30 @@ public class MergeAudioExec extends SingleOrMultiSourceExecBase<MergeAudioOperat
             = "cd {{{tempDir}}} && {{{ffmpeg}}} -f concat -i {{{playlist.path}}} -codec copy -y {{{padded}}}";
 
     public static final String MERGE_AUDIO_TEMPLATE
-            = "{{{ffmpeg}}} -i {{{source.path}}} -i {{audio.path}} "
+            = "{{{ffmpeg}}} -i {{{source.path}}} -itsoffset {{start}} -i {{audio.path}} "
+            // if source has no audio, define a null audio input source
+            + "{{#unless source.hasAudio}}"
+              + "-i anullsrc=channel_layout={{audio.channelLayout}}:sample_rate={{audio.samplingRate}} "
+            + "{{/unless}}"
+
+            + "-filter_complex \""
             + "{{#if source.hasAudio}}"
-              + "-filter_complex \""
+              // source has audio -- mix with insertion
               + "[0:a][1:a] amix=inputs=2 [merged]"
-              + "\" "
-              + "-map 0:v -map \"[merged]\" -c:v copy "
             + "{{else}}"
-              + "-map 0:v -map 1:a -c:v copy -c:a copy "
+              // source has no audio -- mix null source with insertion
+              + "[1:a] aresample=ocl={{audio.channelLayout}}:osr={{audio.samplingRate}} [1a]; "
+              + "[2:a][1a] amix=inputs=2 [merged]"
             + "{{/if}}"
+            + "\" "
+            + "-map 0:v -map \"[merged]\" -c:v copy "
             + "-y {{{output.path}}}";
 
     @Override protected String getProcessTemplate() { return MERGE_AUDIO_TEMPLATE; }
 
-    @Override
-    protected void addCommandContext(MergeAudioOperation op, JSingleOperationContext opCtx, Map<String, Object> ctx) {
+    @Override protected void addCommandContext(MergeAudioOperation op,
+                                               JSingleOperationContext opCtx,
+                                               Map<String, Object> ctx) {
         final JAsset audio = opCtx.assetManager.resolve(op.getInsert());
         final JsEngine js = opCtx.toolbox.getJs();
         final BigDecimal insertAt = op.getAt(ctx, js);
@@ -64,7 +73,7 @@ public class MergeAudioExec extends SingleOrMultiSourceExecBase<MergeAudioOperat
         final Map<String, Object> ctx = new HashMap<>();
         ctx.put("ffmpeg", toolbox.getFfmpeg());
 
-        final JStreamType streamType = audio.getFormat().getStreamType();
+        final JStreamType streamType = audio.audioExtension();
         final JAsset padded = new JAsset().setPath(abs(assetManager.assetPath(op, audio, streamType)));
         final String paddedName = basename(padded.getPath());
         ctx.put("padded", paddedName);
@@ -98,6 +107,9 @@ public class MergeAudioExec extends SingleOrMultiSourceExecBase<MergeAudioOperat
 
         log.debug("padWithSilence: command output: "+scriptOutput);
 
+        // initialize metadata
+        padded.init(assetManager, toolbox);
+
         return padded;
     }
 

src/main/java/jvc/operation/exec/OverlayExec.java

@@ -13,19 +13,38 @@ import java.io.File;
 import java.math.BigDecimal;
 import java.util.Map;
 
+import static java.math.BigDecimal.ZERO;
 import static org.cobbzilla.util.io.FileUtil.abs;
 
 @Slf4j
 public class OverlayExec extends ExecBase<OverlayOperation> {
 
     public static final String OVERLAY_TEMPLATE
-            = "ffmpeg -i {{{source.path}}} -i {{{overlay.path}}} "
+            = "ffmpeg -i {{{source.path}}} "
             + "{{#if hasMainStart}}-ss {{mainStart}} {{/if}}"
             + "{{#if hasMainEnd}}-t {{mainDuration}} {{/if}}"
+            + "-i {{{overlay.path}}} "
+
             + "-filter_complex \""
-            + "[1:v] setpts=PTS-STARTPTS+(1/TB){{#exists width}}, scale={{width}}x{{height}}{{/exists}} [1v]; "
-            + "[0:v][1v] overlay={{{overlayFilterConfig}}} "
-            + "\" -y {{{output.path}}}";
+            + "[1:v] setpts=PTS-STARTPTS"
+            + "{{#exists width}}, scale={{width}}x{{height}}{{/exists}}"
+            + " [1v]; "
+            + "[0:v][1v] overlay={{{overlayFilterConfig}}} [v]; "
+
+            + "{{#if source.hasAudio}}"
+              // source has audio -- mix with overlay
+              + "[1:a] setpts=PTS-STARTPTS{{#if hasOverlayStart}}-({{overlayStart}}/TB){{/if}} [1a]; "
+              + "[0:a][1a] amix=inputs=2 [merged]"
+            + "{{else}}"
+              // source has no audio -- mix null source with overlay
+              + "anullsrc=channel_layout={{overlay.channelLayout}}:sample_rate={{overlay.samplingRate}}:duration={{source.duration}} [silence]; "
+              // + "[1:a] setpts=PTS-STARTPTS{{#if hasOverlayStart}}-({{overlayStart}}/TB){{/if}} [1a]; "
+              + "[silence][1:a] amix=inputs=2 [merged]"
+            + "{{/if}}"
+
+            + "\" "
+            + "-map \"[v]\" -map \"[merged]\" "
+            + " -y {{{output.path}}}";
 
     @Override public Map<String, Object> operate(OverlayOperation op, Toolbox toolbox, AssetManager assetManager) {
 
@@ -81,7 +100,14 @@ public class OverlayExec extends ExecBase<OverlayOperation> {
         final StringBuilder b = new StringBuilder();
         final BigDecimal startTime = overlay.getStartTime(ctx, js);
         final BigDecimal endTime = overlay.hasEndTime() ? overlay.getEndTime(ctx, js) : overlaySource.duration();
-        b.append("enable=between(t\\,").append(startTime).append("\\,").append(endTime).append(")");
+        ctx.put("overlayStart", startTime.doubleValue());
+        ctx.put("hasOverlayStart", !startTime.equals(ZERO));
+        ctx.put("overlayEnd", endTime.doubleValue());
+        b.append("enable=between(t\\,")
+                .append(startTime.doubleValue())
+                .append("\\,")
+                .append(endTime.doubleValue())
+                .append(")");
 
         if (overlay.hasX() && overlay.hasY()) {
             b.append(":x=").append(overlay.getX(ctx, js).intValue())