librtmp: refine comment for NALU process.

@@ -181,11 +181,11 @@ int main(int argc, char** argv)
         
         // 5bits, 7.3.1 NAL unit syntax,
         // H.264-AVC-ISO_IEC_14496-10.pdf, page 44.
-        //  7: SPS, 8: PPS, 5: I Frame, 1: P Frame, 9: AUD
+        //  7: SPS, 8: PPS, 5: I Frame, 1: P Frame, 9: AUD, 6: SEI
         u_int8_t nut = (char)data[nb_start_code] & 0x1f;
         srs_human_trace("sent packet: type=%s, time=%d, size=%d, fps=%.2f, b[%d]=%#x(%s)",
             srs_human_flv_tag_type2string(SRS_RTMP_TYPE_VIDEO), dts, size, fps, nb_start_code, (char)data[nb_start_code],
-            (nut == 7? "SPS":(nut == 8? "PPS":(nut == 5? "I":(nut == 1? "P":(nut == 9? "AUD":"Unknown"))))));
+            (nut == 7? "SPS":(nut == 8? "PPS":(nut == 5? "I":(nut == 1? "P":(nut == 9? "AUD":(nut == 6? "SEI":"Unknown")))))));
         
         // @remark, when use encode device, it not need to sleep.
         if (count == 10) {

@@ -1297,9 +1297,10 @@ int srs_write_h264_ipb_frame(Context* context,
     // 5bits, 7.3.1 NAL unit syntax,
     // H.264-AVC-ISO_IEC_14496-10.pdf, page 44.
     //  5: I Frame, 1: P/B Frame
-    // @remark for rtmp, we only need to send the I/P/B frames to server,
-    //      the aud is used for server to remux stream to annexb.
-    // TODO: FIXME: we must group NALUs between AUD to a frame.
+    // @remark we already group sps/pps to sequence header frame;
+    //      for I/P NALU, we send them in isolate frame, each NALU in a frame;
+    //      for other NALU, for example, AUD/SEI, we just ignore them, because
+    //      AUD used in annexb to split frame, while SEI generally we can ignore it.
     SrsAvcNaluType nut = (SrsAvcNaluType)(frame[0] & 0x1f);
     if (nut != SrsAvcNaluTypeIDR && nut != SrsAvcNaluTypeNonIDR) {
         return ret;