add remove-track operation, refactor a bit

README.md

@@ -123,7 +123,7 @@ Most of the operation settings can be JavaScript expressions, for example:
 The above would set the `start` value to ten seconds before the end of `someAsset`.
 
 ### Supported Operations
-Today, JVCL supports seven basic operations.
+Today, JVCL supports several basic operations.
 
 For each operation listed below, the header links to an example from the JVCL test suite.
 
@@ -149,26 +149,38 @@ For transforming still images into video via a fade-pan (aka Ken Burns) effect.
 Transform a video in one size to another size using black letterboxes on the sides or top/bottom.
 Handy for embedding mobile videos into other screen formats.
 
+### [remove-track](src/test/resources/tests/test_remove_track.jvcl)
+For transforming still images into video via a fade-pan (aka Ken Burns) effect.
+
 # Complex Example
 Here is a complex example using multiple assets and operations.
 
+Note that comments, which are not usually legal in JSON, are allowed in JVCL files.
+
+If you have other JSON-aware tools that need to read JVLC files, you may not want to
+use this comment syntax. The `asset` and `operation` JSON objects also support a `comment`
+field, which can be used as well.
+
 ```json
 {
   "assets": [
     // file -- will be referenced directory
     {
+      "comment": "first video, already local",
       "name": "vid1",
       "path": "/tmp/path/to/video1.mp4"
     },
 
     // URL -- will be downloaded to scratch directory and referenced from there
     {
+      "comment": "second video, will be downloaded",
       "name": "vid2",
       "path": "https://archive.org/download/gov.archives.arc.1257628/gov.archives.arc.1257628_512kb.mp4"
     },
 
     // URL -- will be downloaded to `dest` directory and referenced from there
     {
+      "comment": "third video, will be downloaded",
       "name": "vid3",
       "path": "https://archive.org/download/gov.archives.arc.49442/gov.archives.arc.49442_512kb.mp4",
       "dest": "src/test/resources/sources/"
@@ -176,13 +188,16 @@ Here is a complex example using multiple assets and operations.
 
     // Image URL
     {
+      "comment": "JPEG image, will be downloaded",
       "name": "img1",
       "path": "https://live.staticflickr.com/65535/48159911972_01efa0e5ea_b.jpg",
       "dest": "src/test/resources/sources/"
     }
   ],
   "operations": [
+    // scale examples
     {
+      "comment": "scale using explicity height x width",
       "operation": "scale",            // name of the operation
       "creates": "vid2_scaled",        // asset it creates
       "source": "vid2",                // source asset
@@ -190,33 +205,45 @@ Here is a complex example using multiple assets and operations.
       "height": "768"                  // height of scaled asset. if omitted and width is present, height will be proportional
     },
     {
+      "comment": "scale proportionally by a scale factor",
       "operation": "scale",            // name of the operation
       "creates": "vid2_big",           // asset it creates
       "source": "vid2",                // source asset
       "factor": "2.2"                 // scale factor. if factor is set, width and height are ignored.
     },
+
+    // split example
     {
+      "comment": "split one asset into many",
       "operation": "split",            // name of the operation
       "creates": "vid1_split_%",       // assets it creates, the '%' will be replaced with a counter
       "source": "vid1",                // split this source asset
       "interval": "10"                 // split every ten seconds
     },
+
+    // concat examples
     {
+      "comment": "re-combine previously split assets back together",
       "operation": "concat",           // name of the operation
       "creates": "recombined_vid1",    // assets it creates, the '%' will be replaced with a counter
       "source": ["vid1_split"]         // recombine all split assets
     },
     {
+      "comment": "append vid2 to the end of vid1 and create a new asset",
       "operation": "concat",           // name of the operation
-      "creates": "combined_vid",       // asset it creates, can be referenced later
+      "creates": "combined_vid2",      // asset it creates, can be referenced later
       "source": ["vid1", "vid2"]       // operation-specific: this says, concatenate these named assets
     },
     {
+      "comment": "re-combine only some of the previously split assets",
       "operation": "concat",           // name of the operation
-      "creates": "combined_vid",       // the asset it creates, can be referenced later
-      "source": ["vid1", "vid2"]       // operation-specific: this says, concatenate these named assets
+      "sources": ["vid1_splits[1..2]"],// concatentate these sources -- the 2nd and 3rd files only
+      "creates": "combined_vid3"       // name of the output asset, will be written to scratch directory
     },
+
+    // trim example
     {
+      "comment": "trim all of the assets that were split above",
       "operation": "trim",          // name of the operation
       "creates": {                  // create multiple files, will be prefixed with `name`, store them in `dest`
         "name": "vid1_trims",
@@ -226,7 +253,10 @@ Here is a complex example using multiple assets and operations.
       "start": "1",                  // cropped region starts here, default is zero
       "end": "6"                     // cropped region ends here, default is end of video
     },
+
+    // overlay example
     {
+      "comment": "overlay one video onto another",
       "operation": "overlay",          // name of the operation
       "creates": "overlay1",           // asset it creates
       "source": "combined_vid1",       // main video asset
@@ -242,7 +272,10 @@ Here is a complex example using multiple assets and operations.
         "y": "source.height / 2"       // vertical overlay position on main video. default is 0
       }
     },
+
+    // ken-burns example
     {
+      "comment": "apply zoom-pan effect to image, creates video",
       "operation": "ken-burns",        // name of the operation
       "creates": "ken1",               // asset it creates
       "source": "img1",                // source image
@@ -256,13 +289,43 @@ Here is a complex example using multiple assets and operations.
       "width": "1024",                 // width of output video
       "height": "768"                  // height of output video
     },
+
+    // letterbox example
     {
+      "comment": "increase video size without scaling, add letterboxes as needed",
       "operation": "letterbox",        // name of the operation
       "creates": "boxed1",             // asset it creates
       "source": "ken1",                // source asset
       "width": "source.width * 1.5",   // make it wider
       "height": "source.height * 0.9", // and shorter
       "color": "AliceBlue"             // default is black. can be a hex value (0xff0000 for red) or a color name from here: https://ffmpeg.org/ffmpeg-utils.html#color-syntax
+    },
+
+    // remove-track examples
+    {
+      "comment": "remove all audio tracks",
+      "operation": "remove-track",     // name of the operation
+      "creates": "vid2_video_only",    // name of the output asset
+      "source": "vid2",                // main video asset
+      "track": "audio"                 // remove all audio tracks
+    },
+    {
+      "comment": "remove all video tracks",
+      "operation": "remove-track",     // name of the operation
+      "creates": "vid2_audio_only",    // name of the output asset
+      "source": "vid2",                // main video asset
+      "track": "video"                 // remove all video tracks
+    },
+    {
+      "comment": "remove a specific audio track",
+      "operation": "remove-track",     // name of the operation
+      "creates": "vid2_video_only2",   // name of the output asset
+      "source": "vid2",                // main video asset
+      "track": {
+        // only remove the first audio track
+        "type": "audio",               // track type to remove
+        "number": "0"                  // track number to remove
+      }
     }
   ]
 }

src/main/java/jvcl/model/JAsset.java

@@ -3,6 +3,8 @@ package jvcl.model;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.databind.JsonNode;
 import jvcl.model.info.JMediaInfo;
+import jvcl.model.info.JTrack;
+import jvcl.model.info.JTrackType;
 import jvcl.service.AssetManager;
 import jvcl.service.Toolbox;
 import lombok.*;
@@ -113,6 +115,9 @@ public class JAsset implements JsObjectView {
     }
     public boolean hasInfo() { return info != null; }
 
+    @Getter @Setter private String comment;
+    public boolean hasComment () { return !empty(comment); }
+
     @Override public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
@@ -153,6 +158,10 @@ public class JAsset implements JsObjectView {
     public BigDecimal height() { return hasInfo() ? getInfo().height() : null; }
     @JsonIgnore public BigDecimal getHeight () { return height(); }
 
+    public int numTracks(JTrackType type) { return hasInfo() ? getInfo().numTracks(type) : 0; }
+
+    public JTrack firstTrack(JTrackType type) { return hasInfo() ? getInfo().firstTrack(type) : null; }
+
     public BigDecimal aspectRatio() {
         final BigDecimal width = width();
         final BigDecimal height = height();

src/main/java/jvcl/model/JFileExtension.java

@@ -1,12 +1,14 @@
 package jvcl.model;
 
 import com.fasterxml.jackson.annotation.JsonCreator;
+import jvcl.model.info.JTrack;
 import jvcl.model.info.JTrackType;
 import lombok.AllArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 
 import static jvcl.model.info.JTrackType.*;
 
-@AllArgsConstructor
+@AllArgsConstructor @Slf4j
 public enum JFileExtension {
 
     mp4  (".mp4",  video),
@@ -16,7 +18,9 @@ public enum JFileExtension {
     flac (".flac", audio),
     png  (".png",  image),
     jpg  (".jpg",  image),
-    jpeg (".jpeg", image);
+    jpeg (".jpeg", image),
+    sub  (".sub",  subtitle),
+    dat  (".dat",  data);
 
     @JsonCreator public static JFileExtension fromString(String v) { return valueOf(v.toLowerCase()); }
 
@@ -31,4 +35,22 @@ public enum JFileExtension {
     private final JTrackType mediaType;
     public JTrackType mediaType() { return mediaType; }
 
+    public static JFileExtension fromTrack(JTrack track) {
+        if (track.hasFileExtension()) {
+            try {
+                return fromString(track.getFileExtension());
+            } catch (Exception e) {
+                log.warn("fromTrack: unrecognized file extension: "+track.getFileExtension());
+            }
+        }
+        if (track.hasFormat()) {
+            try {
+                return fromString(track.getFormat());
+            } catch (Exception e) {
+                log.warn("fromTrack: unrecognized format: "+track.getFormat());
+            }
+        }
+        return null;
+    }
+
 }

src/main/java/jvcl/model/JTrackId.java

@@ -0,0 +1,34 @@
+package jvcl.model;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import jvcl.model.info.JTrackType;
+import lombok.Getter;
+import lombok.Setter;
+import lombok.experimental.Accessors;
+
+import static org.cobbzilla.util.daemon.ZillaRuntime.die;
+import static org.cobbzilla.util.json.JsonUtil.json;
+
+@Accessors(chain=true)
+public class JTrackId {
+
+    @Getter @Setter private JTrackType type;
+    @Getter @Setter private Integer number;
+    public boolean hasNumber () { return number != null; }
+
+    public static JTrackId createTrackId (JsonNode val) {
+        if (val == null) return die("createTrackId: constructor val was null");
+        if (val.isObject()) {
+            return json(json(val), JTrackId.class);
+        } else {
+            final JTrackType trackType;
+            try {
+                trackType = JTrackType.fromString(val.asText());
+            } catch (Exception e) {
+                return die("createTrackId: not a valid track type: "+val.asText());
+            }
+            return new JTrackId().setType(trackType);
+        }
+    }
+
+}

src/main/java/jvcl/model/info/JMediaInfo.java

@@ -1,22 +1,34 @@
 package jvcl.model.info;
 
-import jvcl.model.JFormat;
 import jvcl.model.JFileExtension;
+import jvcl.model.JFormat;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 import lombok.Setter;
 import lombok.extern.slf4j.Slf4j;
 
 import java.math.BigDecimal;
+import java.util.concurrent.atomic.AtomicReference;
 
 import static java.math.BigDecimal.ZERO;
 import static org.cobbzilla.util.daemon.ZillaRuntime.*;
 
-@Slf4j
+@NoArgsConstructor @Slf4j
 public class JMediaInfo {
 
+    public JMediaInfo (JMediaInfo other, JFormat format) {
+        this.media = other.getMedia();
+        this.formatRef.set(format);
+    }
+
     @Getter @Setter private JMedia media;
-    @Getter(lazy=true) private final JFormat format = initFormat();
-    public boolean hasFormat () { return getFormat() != null; }
+
+    private final AtomicReference<JFormat> formatRef = new AtomicReference<>();
+
+    public JFormat getFormat () {
+        if (formatRef.get() == null) formatRef.set(initFormat());
+        return formatRef.get();
+    }
 
     private JFormat initFormat () {
         if (media == null || empty(media.getTrack())) return null;
@@ -106,4 +118,21 @@ public class JMediaInfo {
         return null;
     }
 
+    public int numTracks(JTrackType type) {
+        if (media == null || empty(media.getTrack())) return 0;
+        int count = 0;
+        for (JTrack t : media.getTrack()) {
+            if (t.type() == type) count++;
+        }
+        return count;
+    }
+
+    public JTrack firstTrack(JTrackType type) {
+        if (media == null || empty(media.getTrack())) return null;
+        for (JTrack t : media.getTrack()) {
+            if (t.type() == type) return t;
+        }
+        return null;
+    }
+
 }

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

@@ -33,6 +33,8 @@ public class JTrack {
     public boolean hasFileExtension () { return !empty(fileExtension); }
 
     @JsonProperty("Format") @Getter @Setter private String format;
+    public boolean hasFormat () { return !empty(format); }
+
     @JsonProperty("Format_AdditionalFeatures") @Getter @Setter private String formatAdditionalFeatures;
     @JsonProperty("Format_Profile") @Getter @Setter private String formatProfile;
     @JsonProperty("Format_Level") @Getter @Setter private String formatLevel;

src/main/java/jvcl/model/info/JTrackType.java

@@ -7,16 +7,21 @@ import lombok.AllArgsConstructor;
 @AllArgsConstructor
 public enum JTrackType {
 
-    general (null),
-    audio   (JFileExtension.flac),
-    video   (JFileExtension.mp4),
-    image   (JFileExtension.png),
-    other   (null);
+    general (null, null),
+    audio   (JFileExtension.flac, "a"),
+    video   (JFileExtension.mp4, "v"),
+    image   (JFileExtension.png, null),
+    subtitle(JFileExtension.png, "s"),
+    data    (JFileExtension.png, "d"),
+    other   (null, null);
 
     @JsonCreator public static JTrackType fromString(String val) { return valueOf(val.toLowerCase()); }
 
     private final JFileExtension ext;
-
     public JFileExtension ext() { return ext; }
 
+    private final String ffmpegType;
+    public String ffmpegType() { return ffmpegType; }
+    public boolean hasFfmpegType() { return ffmpegType != null; }
+
 }

src/main/java/jvcl/model/operation/JOperation.java

@@ -14,6 +14,7 @@ import java.util.HashMap;
 import java.util.Map;
 
 import static jvcl.service.json.JOperationFactory.getOperationExecClass;
+import static org.cobbzilla.util.daemon.ZillaRuntime.empty;
 import static org.cobbzilla.util.daemon.ZillaRuntime.hashOf;
 import static org.cobbzilla.util.json.JsonUtil.json;
 import static org.cobbzilla.util.reflect.ReflectionUtil.instantiate;
@@ -33,6 +34,9 @@ public abstract class JOperation {
     @Getter @Setter private JsonNode creates;
     @Getter @Setter private boolean noExec = false;
 
+    @Getter @Setter private String comment;
+    public boolean hasComment () { return !empty(comment); }
+
     public String hash(JAsset[] sources) { return hash(sources, null); }
 
     public String hash(JAsset[] sources, Object[] args) {

src/main/java/jvcl/model/operation/JSingleSourceOperation.java

@@ -23,7 +23,7 @@ public class JSingleSourceOperation extends JOperation {
         final JAsset output = json2asset(getCreates());
         output.mergeFormat(source.getFormat());
 
-        // ensure output is in the correct fprmat
+        // ensure output is in the correct format
         final JFormat format = output.getFormat();
         final JTrackType type = outputMediaType();
         if (!format.hasFileExtension() || format.getFileExtension().mediaType() != type) {
@@ -33,12 +33,12 @@ public class JSingleSourceOperation extends JOperation {
             }
             format.setFileExtension(ext);
         }
-        final JFileExtension formatType = getFileExtension(output);
+        final JFileExtension formatType = getFileExtension(source, output);
 
         return new JSingleOperationContext(source, output, formatType);
     }
 
-    protected JFileExtension getFileExtension(JAsset output) {
+    protected JFileExtension getFileExtension(JAsset source, JAsset output) {
         return output.getFormat().getFileExtension();
     }
 

src/main/java/jvcl/operation/RemoveTrackOperation.java

@@ -0,0 +1,58 @@
+package jvcl.operation;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.databind.JsonNode;
+import jvcl.model.JAsset;
+import jvcl.model.JFileExtension;
+import jvcl.model.JFormat;
+import jvcl.model.JTrackId;
+import jvcl.model.info.JMediaInfo;
+import jvcl.model.info.JTrack;
+import jvcl.model.info.JTrackType;
+import jvcl.model.operation.JSingleSourceOperation;
+import lombok.Getter;
+import lombok.Setter;
+
+import static jvcl.model.JTrackId.createTrackId;
+import static org.cobbzilla.util.daemon.ZillaRuntime.die;
+
+public class RemoveTrackOperation extends JSingleSourceOperation {
+
+    @Getter @Setter private JsonNode track;
+
+    @JsonIgnore @Getter(lazy=true) private final JTrackId trackId = initTrackId();
+    private JTrackId initTrackId() {
+        final JTrackId trackId = createTrackId(getTrack());
+        final JTrackType trackType = trackId.getType();
+        if (!trackType.hasFfmpegType()) die("initTrackType: cannot remove tracks of type "+ trackType);
+        return trackId;
+    }
+
+    @Override protected JFileExtension getFileExtension(JAsset source, JAsset output) {
+
+        final JTrackId trackId = getTrackId();
+        final JTrackType trackType = trackId.getType();
+
+        // if we are removing all video tracks, the output will be an audio asset
+        final int trackCount = source.numTracks(trackType);
+        if (trackCount == 0) return die("getFileExtension: no tracks of type "+ trackType +" found in source: "+source);
+
+        if (wouldRemoveAllVideoTracks(trackId, trackCount)) {
+            // find the format of the first audio track
+            final JTrack audio = source.firstTrack(JTrackType.audio);
+            if (audio == null) return die("getFileExtension: no audio tracks found!");
+            final JFileExtension ext = JFileExtension.fromTrack(audio);
+            source.setInfo(new JMediaInfo(source.getInfo(), new JFormat().setFileExtension(ext)));
+            return ext;
+        }
+
+        return super.getFileExtension(source, output);
+    }
+
+    private boolean wouldRemoveAllVideoTracks(JTrackId trackId, int trackCount) {
+        if (trackId.getType() != JTrackType.video) return false;
+        if (!trackId.hasNumber()) return true;
+        return trackCount == 1;
+    }
+
+}

src/main/java/jvcl/operation/exec/LetterboxExec.java

@@ -64,7 +64,6 @@ public class LetterboxExec extends SingleOrMultiSourceExecBase<LetterboxOperatio
                                      JAsset subOutput,
                                      Toolbox toolbox,
                                      AssetManager assetManager) {
-
         ctx.put("source", source);
         ctx.put("output", subOutput);
         final String script = renderScript(toolbox, ctx, LETTERBOX_TEMPLATE);
@@ -72,11 +71,6 @@ public class LetterboxExec extends SingleOrMultiSourceExecBase<LetterboxOperatio
         log.debug("operate: running script: "+script);
         final String scriptOutput = exec(script, op.isNoExec());
         log.debug("operate: command output: "+scriptOutput);
-        if (output == subOutput) {
-            assetManager.addOperationAsset(output);
-        } else {
-            assetManager.addOperationAssetSlice(output, subOutput);
-        }
     }
 
 }

src/main/java/jvcl/operation/exec/RemoveTrackExec.java

@@ -0,0 +1,60 @@
+package jvcl.operation.exec;
+
+import jvcl.model.JAsset;
+import jvcl.model.JFileExtension;
+import jvcl.model.JTrackId;
+import jvcl.model.info.JTrackType;
+import jvcl.model.operation.JSingleOperationContext;
+import jvcl.operation.RemoveTrackOperation;
+import jvcl.service.AssetManager;
+import jvcl.service.Toolbox;
+import lombok.extern.slf4j.Slf4j;
+
+import java.util.HashMap;
+import java.util.Map;
+
+@Slf4j
+public class RemoveTrackExec extends SingleOrMultiSourceExecBase<RemoveTrackOperation> {
+
+    public static final String REMOVE_TRACK_TEMPLATE
+            = "{{{ffmpeg}}} -i {{{source.path}}} "
+            + "-map 0 -map -0:{{trackType}}{{#exists trackNumber}}:{{trackNumber}}{{/exists}} "
+            + "-c copy "
+            + "-y {{{output.path}}}";
+
+    @Override public void operate(RemoveTrackOperation op, Toolbox toolbox, AssetManager assetManager) {
+
+        final JSingleOperationContext opCtx = op.getSingleInputContext(assetManager);
+        final JAsset source = opCtx.source;
+        final JAsset output = opCtx.output;
+        final JFileExtension formatType = opCtx.formatType;
+
+        final Map<String, Object> ctx = new HashMap<>();
+        ctx.put("ffmpeg", toolbox.getFfmpeg());
+        ctx.put("source", source);
+
+        final JTrackId trackId = op.getTrackId();
+        final JTrackType trackType = trackId.getType();
+        ctx.put("trackType", trackType.ffmpegType());
+        if (trackId.hasNumber()) ctx.put("trackNumber", trackId.getNumber());
+
+        operate(op, toolbox, assetManager, source, output, formatType, ctx);
+    }
+
+    @Override protected void process(Map<String, Object> ctx,
+                                     RemoveTrackOperation op,
+                                     JAsset source,
+                                     JAsset output,
+                                     JAsset subOutput,
+                                     Toolbox toolbox,
+                                     AssetManager assetManager) {
+        ctx.put("source", source);
+        ctx.put("output", subOutput);
+        final String script = renderScript(toolbox, ctx, REMOVE_TRACK_TEMPLATE);
+
+        log.debug("operate: running script: "+script);
+        final String scriptOutput = exec(script, op.isNoExec());
+        log.debug("operate: command output: "+scriptOutput);
+    }
+
+}

src/main/java/jvcl/operation/exec/ScaleExec.java

@@ -58,11 +58,6 @@ public class ScaleExec extends SingleOrMultiSourceExecBase<ScaleOperation> {
         log.debug("operate: running script: "+script);
         final String scriptOutput = exec(script, op.isNoExec());
         log.debug("operate: command output: "+scriptOutput);
-        if (output == subOutput) {
-            assetManager.addOperationAsset(output);
-        } else {
-            assetManager.addOperationAssetSlice(output, subOutput);
-        }
     }
 
 }

src/main/java/jvcl/operation/exec/SingleOrMultiSourceExecBase.java

@@ -37,6 +37,7 @@ public abstract class SingleOrMultiSourceExecBase<OP extends JOperation> extends
                 }
                 subOutput.setPath(abs(outfile));
                 process(ctx, op, asset, output, subOutput, toolbox, assetManager);
+                assetManager.addOperationAssetSlice(output, subOutput);
             }
         } else {
             final File defaultOutfile = assetManager.assetPath(op, source, formatType);
@@ -44,6 +45,7 @@ public abstract class SingleOrMultiSourceExecBase<OP extends JOperation> extends
             if (path == null) return;
             output.setPath(abs(path));
             process(ctx, op, source, output, output, toolbox, assetManager);
+            assetManager.addOperationAsset(output);
         }
     }
 
@@ -55,5 +57,4 @@ public abstract class SingleOrMultiSourceExecBase<OP extends JOperation> extends
                                     Toolbox toolbox,
                                     AssetManager assetManager);
 
-
 }

src/main/java/jvcl/operation/exec/TrimExec.java

@@ -55,11 +55,6 @@ public class TrimExec extends SingleOrMultiSourceExecBase<TrimOperation> {
         log.debug("operate: running script: "+script);
         final String scriptOutput = exec(script, op.isNoExec());
         log.debug("operate: command output: "+scriptOutput);
-        if (output == subOutput) {
-            assetManager.addOperationAsset(output);
-        } else {
-            assetManager.addOperationAssetSlice(output, subOutput);
-        }
     }
 
 }

src/test/java/javicle/test/BasicTest.java

@@ -26,8 +26,9 @@ public class BasicTest {
         runSpec("tests/test_letterbox.jvcl");
     }
 
-    @Test public void testOverlay() { runSpec("tests/test_overlay.jvcl"); }
-    @Test public void testKenBurns() { runSpec("tests/test_ken_burns.jvcl"); }
+    @Test public void testOverlay     () { runSpec("tests/test_overlay.jvcl"); }
+    @Test public void testKenBurns    () { runSpec("tests/test_ken_burns.jvcl"); }
+    @Test public void testRemoveTrack () { runSpec("tests/test_remove_track.jvcl"); }
 
     private void runSpec(String specPath) {
         try {

src/test/resources/tests/test_concat.jvcl

@@ -15,7 +15,7 @@
     {
       "operation": "concat",              // name of the operation
       "sources": ["vid1_splits[1..2]"],   // concatentate these sources -- the 2nd and 3rd files only
-      "creates": "combined_vid2",         // name of the output asset, will be written to scratch directory
+      "creates": "combined_vid2"          // name of the output asset, will be written to scratch directory
     }
   ]
 }

src/test/resources/tests/test_remove_track.jvcl

@@ -0,0 +1,42 @@
+{
+  "assets": [
+    // this is a US government video not covered by copyright
+    {
+      "name": "vid2",
+      "path": "https://archive.org/download/gov.archives.arc.49442/gov.archives.arc.49442_512kb.mp4",
+      "dest": "src/test/resources/sources/"
+    }
+  ],
+  "operations": [
+    // trim video first, so test runs faster
+    {
+      "operation": "trim",
+      "creates": "v2",
+      "source": "vid2",
+      "start": "0",
+      "end": "20"
+    },
+    {
+      "operation": "remove-track",     // name of the operation
+      "creates": "vid2_video_only",    // name of the output asset
+      "source": "v2",                  // main video asset
+      "track": "audio"                 // remove all audio tracks
+    },
+    {
+      "operation": "remove-track",     // name of the operation
+      "creates": "vid2_audio_only",    // name of the output asset
+      "source": "v2",                  // main video asset
+      "track": "video"                 // remove all video tracks
+    },
+    {
+      "operation": "remove-track",     // name of the operation
+      "creates": "vid2_video_only2",   // name of the output asset
+      "source": "v2",                  // main video asset
+      "track": {
+        // only remove the first audio track
+        "type": "audio",               // track type to remove
+        "number": "0"                  // track number to remove
+      }
+    }
+  ]
+}