Only add '-vcodec copy' when there is no video filter

Otherwise the video filters aren't run.

Author: abeluck

src/org/ffmpeg/android/FfmpegController.java

@@ -541,7 +541,11 @@ public void concatAndTrimFilesMP4Stream (ArrayList<MediaDesc> videos,MediaDesc o
 
 		MediaDesc mInCat = new MediaDesc();
 		mInCat.path = mCatPath;
-		out.videoCodec = "copy";
+		
+		if( out.videoFilter == null ) {
+			out.videoCodec = "copy";
+		}
+
 		out.audioCodec = "copy";
 		out.audioBitStreamFilter = "aac_adtstoasc";