Reuse a single AvByteBufferDescriptor when depacketizing H264 instead of allocating many of them per packet

src/com/limelight/nvstream/av/AvByteBufferDescriptor.java

@@ -19,6 +19,13 @@ public class AvByteBufferDescriptor {
 		this.length = desc.length;
 	}
 	
+	public void reinitialize(byte[] data, int offset, int length)
+	{
+		this.data = data;
+		this.offset = offset;
+		this.length = length;
+	}
+	
 	public void print()
 	{
 		print(offset, length);

src/com/limelight/nvstream/av/AvShortBufferDescriptor.java

@@ -18,4 +18,11 @@ public class AvShortBufferDescriptor {
 		this.offset = desc.offset;
 		this.length = desc.length;
 	}
+	
+	public void reinitialize(short[] data, int offset, int length)
+	{
+		this.data = data;
+		this.offset = offset;
+		this.length = length;
+	}
 }

src/com/limelight/nvstream/av/video/AvVideoDepacketizer.java

@@ -17,6 +17,10 @@ public class AvVideoDepacketizer {
 	private int avcNalDataLength = 0;
 	private int currentlyDecoding;
 	
+	// Cached buffer descriptor to save on allocations
+	// Only safe to use in decode thread!!!!
+	private AvByteBufferDescriptor cachedDesc;
+	
 	// Sequencing state
 	private short lastSequenceNumber;
 	
@@ -28,6 +32,7 @@ public class AvVideoDepacketizer {
 	public AvVideoDepacketizer(ConnectionStatusListener controlListener)
 	{
 		this.controlListener = controlListener;
+		this.cachedDesc = new AvByteBufferDescriptor(null, 0, 0);
 	}
 	
 	private void clearAvcNalState()
@@ -45,12 +50,11 @@ public class AvVideoDepacketizer {
 			
 			// Check if this is a special NAL unit
 			AvByteBufferDescriptor header = avcNalDataChain.getFirst();
-			AvByteBufferDescriptor specialSeq = NAL.getSpecialSequenceDescriptor(header);
 			
-			if (specialSeq != null)
+			if (NAL.getSpecialSequenceDescriptor(header, cachedDesc))
 			{
 				// The next byte after the special sequence is the NAL header
-				byte nalHeader = specialSeq.data[specialSeq.offset+specialSeq.length];
+				byte nalHeader = cachedDesc.data[cachedDesc.offset+cachedDesc.length];
 				
 				switch (nalHeader)
 				{
@@ -112,16 +116,15 @@ public class AvVideoDepacketizer {
 			int start = location.offset;
 			
 			// Check for a special sequence
-			AvByteBufferDescriptor specialSeq = NAL.getSpecialSequenceDescriptor(location);
-			if (specialSeq != null)
+			if (NAL.getSpecialSequenceDescriptor(location, cachedDesc))
 			{
-				if (NAL.isAvcStartSequence(specialSeq))
+				if (NAL.isAvcStartSequence(cachedDesc))
 				{
 					// We're decoding H264 now
 					currentlyDecoding = AvDecodeUnit.TYPE_H264;
 					
 					// Check if it's the end of the last frame
-					if (NAL.isAvcFrameStart(specialSeq))
+					if (NAL.isAvcFrameStart(cachedDesc))
 					{
 						// Reassemble any pending AVC NAL
 						reassembleAvcNal();
@@ -132,14 +135,14 @@ public class AvVideoDepacketizer {
 					}
 					
 					// Skip the start sequence
-					location.length -= specialSeq.length;
-					location.offset += specialSeq.length;
+					location.length -= cachedDesc.length;
+					location.offset += cachedDesc.length;
 				}
 				else
 				{
 					// Check if this is padding after a full AVC frame
 					if (currentlyDecoding == AvDecodeUnit.TYPE_H264 &&
-						NAL.isPadding(specialSeq)) {
+						NAL.isPadding(cachedDesc)) {
 						// The decode unit is complete
 						reassembleAvcNal();
 					}
@@ -159,15 +162,13 @@ public class AvVideoDepacketizer {
 				// Catch the easy case first where byte 0 != 0x00
 				if (location.data[location.offset] == 0x00)
 				{
-					specialSeq = NAL.getSpecialSequenceDescriptor(location);
-					
 					// Check if this should end the current NAL
-					if (specialSeq != null)
+					if (NAL.getSpecialSequenceDescriptor(location, cachedDesc))
 					{
 						// Only stop if we're decoding something or this
 						// isn't padding
 						if (currentlyDecoding != AvDecodeUnit.TYPE_UNKNOWN ||
-							!NAL.isPadding(specialSeq))
+							!NAL.isPadding(cachedDesc))
 						{
 							break;
 						}
@@ -249,11 +250,11 @@ class NAL {
 	}
 	
 	// Returns a buffer descriptor describing the start sequence
-	public static AvByteBufferDescriptor getSpecialSequenceDescriptor(AvByteBufferDescriptor buffer)
+	public static boolean getSpecialSequenceDescriptor(AvByteBufferDescriptor buffer, AvByteBufferDescriptor outputDesc)
 	{
 		// NAL start sequence is 00 00 00 01 or 00 00 01
 		if (buffer.length < 3)
-			return null;
+			return false;
 		
 		// 00 00 is magic
 		if (buffer.data[buffer.offset] == 0x00 &&
@@ -267,19 +268,21 @@ class NAL {
 					buffer.data[buffer.offset+3] == 0x01)
 				{
 					// It's the AVC start sequence 00 00 00 01
-					return new AvByteBufferDescriptor(buffer.data, buffer.offset, 4);
+					outputDesc.reinitialize(buffer.data, buffer.offset, 4);
 				}
 				else
 				{
 					// It's 00 00 00
-					return new AvByteBufferDescriptor(buffer.data, buffer.offset, 3);
+					outputDesc.reinitialize(buffer.data, buffer.offset, 3);
 				}
+				return true;
 			}
 			else if (buffer.data[buffer.offset+2] == 0x01 ||
 					 buffer.data[buffer.offset+2] == 0x02)
 			{
 				// These are easy: 00 00 01 or 00 00 02
-				return new AvByteBufferDescriptor(buffer.data, buffer.offset, 3);
+				outputDesc.reinitialize(buffer.data, buffer.offset, 3);
+				return true;
 			}
 			else if (buffer.data[buffer.offset+2] == 0x03)
 			{
@@ -290,22 +293,23 @@ class NAL {
 				// or whether it's something else
 				
 				if (buffer.length < 4)
-					return null;
+					return false;
 				
 				if (buffer.data[buffer.offset+3] >= 0x00 &&
 					buffer.data[buffer.offset+3] <= 0x03)
 				{
 					// It's not really a special sequence after all
-					return null;
+					return false;
 				}
 				else
 				{
 					// It's not a standard replacement so it's a special sequence
-					return new AvByteBufferDescriptor(buffer.data, buffer.offset, 3);
+					outputDesc.reinitialize(buffer.data, buffer.offset, 3);
+					return true;
 				}
 			}
 		}
 		
-		return null;
+		return false;
 	}
 }