use reduce_sequence_header for stream control.

@@ -342,6 +342,7 @@ Remark:
 
 ## History
 
+* v2.0, 2015-08-14, use reduce_sequence_header for stream control.
 * v2.0, 2015-08-14, use send_min_interval for stream control. 2.0.183
 * v2.0, 2015-08-12, enable the SRS_PERF_TCP_NODELAY and add config tcp_nodelay. 2.0.182
 * v2.0, 2015-08-11, for [#442](https://github.com/simple-rtmp-server/srs/issues/442) support kickoff connected client. 2.0.181

@@ -876,7 +876,12 @@ vhost stream.control.com {
     # @remark 0 to disable the minimal interval.
     # @remark >0 to make the srs to send message one by one.
     # default: 0
-    send_min_interval   10;
+    send_min_interval       10;
+    # whether reduce the sequence header,
+    # for some client which cannot got duplicated sequence header,
+    # while the sequence header is not changed yet.
+    # default: off
+    reduce_sequence_header  on;
 }
 
 # the vhost for antisuck.

@@ -1761,7 +1761,8 @@ int SrsConfig::check_config()
                 && n != "time_jitter" && n != "mix_correct"
                 && n != "atc" && n != "atc_auto"
                 && n != "debug_srs_upnode"
-                && n != "mr" && n != "mw_latency" && n != "min_latency" && n != "tcp_nodelay" && n != "send_min_interval"
+                && n != "mr" && n != "mw_latency" && n != "min_latency"
+                && n != "tcp_nodelay" && n != "send_min_interval" && n != "reduce_sequence_header"
                 && n != "security" && n != "http_remux"
                 && n != "http" && n != "http_static"
                 && n != "hds"
@@ -2534,6 +2535,23 @@ int SrsConfig::get_send_min_interval(string vhost)
     return ::atoi(conf->arg0().c_str());
 }
 
+bool SrsConfig::get_reduce_sequence_header(string vhost)
+{
+    static bool DEFAULT = false;
+    
+    SrsConfDirective* conf = get_vhost(vhost);
+    if (!conf) {
+        return DEFAULT;
+    }
+    
+    conf = conf->get("reduce_sequence_header");
+    if (!conf || conf->arg0().empty()) {
+        return DEFAULT;
+    }
+    
+    return SRS_CONF_PERFER_FALSE(conf->arg0());
+}
+
 int SrsConfig::get_global_chunk_size()
 {
     SrsConfDirective* conf = root->get("chunk_size");

@@ -530,6 +530,10 @@ public:
      * the minimal send interval in ms.
      */
     virtual int                 get_send_min_interval(std::string vhost);
+    /**
+     * whether reduce the sequence header.
+     */
+    virtual bool                get_reduce_sequence_header(std::string vhost);
 private:
     /**
     * get the global chunk size.

@@ -1535,6 +1535,8 @@ int SrsSource::on_audio_imp(SrsSharedPtrMessage* msg)
     int ret = ERROR_SUCCESS;
     
     srs_info("Audio dts=%"PRId64", size=%d", msg->timestamp, msg->size);
+    bool is_aac_sequence_header = SrsFlvCodec::audio_is_sequence_header(msg->payload, msg->size);
+    bool is_sequence_header = is_aac_sequence_header;
     
 #ifdef SRS_AUTO_HLS
     if ((ret = hls->on_audio(msg)) != ERROR_SUCCESS) {
@@ -1589,11 +1591,16 @@ int SrsSource::on_audio_imp(SrsSharedPtrMessage* msg)
 #endif
     
     // copy to all consumer
-    int nb_consumers = (int)consumers.size();
-    if (nb_consumers > 0) {
-        SrsConsumer** pconsumer = consumers.data();
-        for (int i = 0; i < nb_consumers; i++) {
-            SrsConsumer* consumer = pconsumer[i];
+    bool drop_for_reduce = false;
+    if (is_sequence_header && cache_sh_audio && _srs_config->get_reduce_sequence_header(_req->vhost)) {
+        if (cache_sh_audio->size == msg->size) {
+            drop_for_reduce = srs_bytes_equals(cache_sh_audio->payload, msg->payload, msg->size);
+            srs_warn("drop for reduce sh audio, size=%d", msg->size);
+        }
+    }
+    if (!drop_for_reduce) {
+        for (int i = 0; i < (int)consumers.size(); i++) {
+            SrsConsumer* consumer = consumers.at(i);
             if ((ret = consumer->enqueue(msg, atc, jitter_algorithm)) != ERROR_SUCCESS) {
                 srs_error("dispatch the audio failed. ret=%d", ret);
                 return ret;
@@ -1617,7 +1624,6 @@ int SrsSource::on_audio_imp(SrsSharedPtrMessage* msg)
     // cache the sequence header of aac, or first packet of mp3.
     // for example, the mp3 is used for hls to write the "right" audio codec.
     // TODO: FIXME: to refine the stream info system.
-    bool is_aac_sequence_header = SrsFlvCodec::audio_is_sequence_header(msg->payload, msg->size);
     if (is_aac_sequence_header || !cache_sh_audio) {
         srs_freep(cache_sh_audio);
         cache_sh_audio = msg->copy();
@@ -1740,6 +1746,8 @@ int SrsSource::on_video_imp(SrsSharedPtrMessage* msg)
     
     srs_info("Video dts=%"PRId64", size=%d", msg->timestamp, msg->size);
     
+    bool is_sequence_header = SrsFlvCodec::video_is_sequence_header(msg->payload, msg->size);
+    
 #ifdef SRS_AUTO_HLS
     if ((ret = hls->on_video(msg)) != ERROR_SUCCESS) {
         // apply the error strategy for hls.
@@ -1793,7 +1801,14 @@ int SrsSource::on_video_imp(SrsSharedPtrMessage* msg)
 #endif
     
     // copy to all consumer
-    if (true) {
+    bool drop_for_reduce = false;
+    if (is_sequence_header && cache_sh_video && _srs_config->get_reduce_sequence_header(_req->vhost)) {
+        if (cache_sh_video->size == msg->size) {
+            drop_for_reduce = srs_bytes_equals(cache_sh_video->payload, msg->payload, msg->size);
+            srs_warn("drop for reduce sh video, size=%d", msg->size);
+        }
+    }
+    if (!drop_for_reduce) {
         for (int i = 0; i < (int)consumers.size(); i++) {
             SrsConsumer* consumer = consumers.at(i);
             if ((ret = consumer->enqueue(msg, atc, jitter_algorithm)) != ERROR_SUCCESS) {
@@ -1818,7 +1833,7 @@ int SrsSource::on_video_imp(SrsSharedPtrMessage* msg)
 
     // cache the sequence header if h264
     // donot cache the sequence header to gop_cache, return here.
-    if (SrsFlvCodec::video_is_sequence_header(msg->payload, msg->size)) {
+    if (is_sequence_header) {
         srs_freep(cache_sh_video);
         cache_sh_video = msg->copy();
         
@@ -2062,13 +2077,12 @@ void SrsSource::on_unpublish()
     hds->on_unpublish();
 #endif
 
+    // only clear the gop cache metadata,
+    // donot clear the sequence header, for it maybe not changed.
     gop_cache->clear();
-
     srs_freep(cache_metadata);
-    srs_freep(cache_sh_video);
-    srs_freep(cache_sh_audio);
     
-    srs_info("clear cache/metadata/sequence-headers when unpublish.");
+    srs_info("clear cache/metadata when unpublish.");
     srs_trace("cleanup when unpublish");
     
     _can_publish = true;