Fix AV1 packetizer length field for 127-byte fragments

packetize(List) used the 2-byte LEB128 length branch for any fragment
>= 127 bytes, but 127 fits in a single LEB128 byte (0x7F). For an exactly
127-byte fragment LEB128.encode returned 0x7F and the 2-byte split wrote
a malformed length of [0x00, 0x7F]; the depacketizer then read a
zero-length fragment followed by a spurious second OBU, splitting one OBU
into two and corrupting the frame.

Use the 2-byte branch only for sizes > 127. Verified: a frame whose final
fragment is exactly 127 bytes now reconstructs to a single OBU of the
full length (previously two elements).

Caught by the byte-for-byte AV1 framing self-check added on the consumer
side.

Author: mondain

io/src/main/java/org/red5/io/rtp/AV1Packetizer.java

@@ -292,7 +292,7 @@ public List<byte[]> packetize(List<OBUInfo> obuInfos, int mtu) {
                     int currentFragmentSize = Math.min(maxFragmentSize, payloadDataRemaining);
                     int leb128Value = LEB128.encode(currentFragmentSize);
                     byte[] out;
-                    if (currentFragmentSize >= 127) { // leb takes at least 2 bytes
+                    if (currentFragmentSize > 127) { // leb takes 2 bytes only above 127 (0-127 fit in one byte)
                         int outLen = aggregationHeaderLength + 2 + currentFragmentSize;
                         out = new byte[outLen];
                         out[1] = (byte) (leb128Value >> 8);