Merge pull request #226 from Atlas42/ttl-multicast

Multicast TTL configuration flag added

docs/README.md

@@ -112,6 +112,7 @@ stream->configure_ctx(RCC_PKT_MAX_DELAY, 150);
 | RCC_POLL_TIMEOUT     | Set the timeout value for polling the socket. | 100 ms | Receiver|
 | RCC_SSRC             | Set the SSSRC value for this media stream. | random uint32 | Sender|
 | RCC_REMOTE_SSRC      | Set the remote SSRC value that this media stream should receive packets from. | random uint32 | Receiver|
+| RCC_MULTICAST_TTL    | Set the sender packets IP TTL (Time to Live) for multicast. Must be in range [1, 255]. | system default | Sender |
 
 ### RTP frame flags
 
@@ -173,7 +174,7 @@ The default behavior of uvgRTP video reception when there is packet loss is to g
 
 ## Trouble receiving burst of packets?
 
-The default configuration of uvgRTP should be able to handle most basic scenarios up to 4K60p without any frame loss. If you are however 1) using a higher resolution, 2) higher fps value, 3) using a low power machine to receive the RTP stream, or 4) you are experiencing frame loss, you might consider setting or increasing the following parameters: 
+The default configuration of uvgRTP should be able to handle most basic scenarios up to 4K60p without any frame loss. If you are however 1) using a higher resolution, 2) higher fps value, 3) using a low power machine to receive the RTP stream, or 4) you are experiencing frame loss, you might consider setting or increasing the following parameters:
 * RCC_UDP_RCV_BUF_SIZE: You can try increasing this to 40 or 80 MB if it helps receiving frames
 * RCC_UDP_SND_BUF_SIZE_ You can try increasing this to 40 or 80 MB if it helps sending frames
 * RCC_RING_BUFFER_SIZE: You can try increasing this to 8 or 16 MB if it helps receiving frames

include/uvgrtp/media_stream.hh

@@ -461,6 +461,7 @@ namespace uvgrtp {
             // Values are initialized to -2, which means value not set
             int snd_buf_size_;
             int rcv_buf_size_;
+            int multicast_ttl_;
     };
 }
 

include/uvgrtp/util.hh

@@ -389,6 +389,12 @@ enum RTP_CTX_CONFIGURATION_FLAGS {
     */
     RCC_POLL_TIMEOUT       = 13,
 
+    /** Set the sender packets IP TTL (Time to Live) for multicast
+     *
+     * Must be in range [1, 255]. Keep the system default if not set.
+     */
+    RCC_MULTICAST_TTL = 15,
+
     /// \cond DO_NOT_DOCUMENT
     RCC_LAST
     /// \endcond

src/media_stream.cc

@@ -63,7 +63,8 @@ uvgrtp::media_stream::media_stream(std::string cname, std::string remote_addr,
     ssrc_(std::make_shared<std::atomic<std::uint32_t>>(uvgrtp::random::generate_32())),
     remote_ssrc_(std::make_shared<std::atomic<std::uint32_t>>(ssrc_.get()->load() + 1)),
     snd_buf_size_(-1),
-    rcv_buf_size_(-1)
+    rcv_buf_size_(-1),
+    multicast_ttl_(-1)
 {
 }
 
@@ -936,6 +937,15 @@ rtp_error_t uvgrtp::media_stream::configure_ctx(int rcc_flag, ssize_t value)
             *remote_ssrc_ = (uint32_t)value;
             break;
         }
+        case RCC_MULTICAST_TTL: {
+            if (value <= 0 || value > 255)
+                return RTP_INVALID_VALUE;
+
+            int multicast_ttl = (int)value;
+            multicast_ttl_ = multicast_ttl;
+            ret = socket_->setsockopt(IPPROTO_IP, IP_MULTICAST_TTL, (const char*)&multicast_ttl, sizeof(int));
+            break;
+        }
         default:
             return RTP_INVALID_VALUE;
     }
@@ -993,6 +1003,9 @@ int uvgrtp::media_stream::get_configuration_value(int rcc_flag)
         case RCC_POLL_TIMEOUT: {
             return reception_flow_->get_poll_timeout_ms();
         }
+        case RCC_MULTICAST_TTL: {
+            return multicast_ttl_;
+        }
         default:
             ret = -1;
     }

test/test_2_rtp.cpp

@@ -202,6 +202,8 @@ TEST(RTPTests, rtp_configuration)
 
         sender->configure_ctx(RCC_FPS_NUMERATOR, 100);
         sender->configure_ctx(RCC_FPS_DENOMINATOR, 1);
+
+        sender->configure_ctx(RCC_MULTICAST_TTL, 1);
     }
 
     if (receiver)