diff --git a/README.md b/README.md
index 21a10b52f..761e87dac 100755
--- a/README.md
+++ b/README.md
@@ -153,6 +153,7 @@ For previous versions, please read:
 
 ## V4 changes
 
+* v4.0, 2020-03-13, For [#1636][bug #1636], fix bug for mux AAC to ADTS, never overwrite by RTMP sampling rate. 4.0.13
 * v4.0, 2020-03-07, For [#1612][bug #1612], fix crash bug for RTSP. 4.0.12
 * v4.0, 2020-03-07, For [#1631][bug #1631], support sei_filter for SRT. 4.0.11
 * v4.0, 2020-03-01, For [#1621][bug #1621], support mix_correct for aggregate aac for SRT. 4.0.10
diff --git a/trunk/src/core/srs_core_version4.hpp b/trunk/src/core/srs_core_version4.hpp
index 98f2899e1..dbb90abd4 100644
--- a/trunk/src/core/srs_core_version4.hpp
+++ b/trunk/src/core/srs_core_version4.hpp
@@ -24,6 +24,6 @@
 #ifndef SRS_CORE_VERSION4_HPP
 #define SRS_CORE_VERSION4_HPP
 
-#define SRS_VERSION4_REVISION 12
+#define SRS_VERSION4_REVISION 13
 
 #endif
diff --git a/trunk/src/kernel/srs_kernel_codec.hpp b/trunk/src/kernel/srs_kernel_codec.hpp
index 2f8d436b6..a8d674c2b 100644
--- a/trunk/src/kernel/srs_kernel_codec.hpp
+++ b/trunk/src/kernel/srs_kernel_codec.hpp
@@ -304,6 +304,9 @@ extern int srs_flv_srates[];
  */
 extern int srs_aac_srates[];
 
+// The number of aac samplerates, size for srs_aac_srates.
+#define SrsAAcSampleRateNumbers 16
+
 // The impossible aac sample rate index.
 #define SrsAacSampleRateUnset 15
 
diff --git a/trunk/src/protocol/srs_raw_avc.cpp b/trunk/src/protocol/srs_raw_avc.cpp
index da0fd1835..f05af8221 100644
--- a/trunk/src/protocol/srs_raw_avc.cpp
+++ b/trunk/src/protocol/srs_raw_avc.cpp
@@ -438,7 +438,6 @@ srs_error_t SrsRawAacStream::adts_demux(SrsBuffer* stream, char** pframe, int* p
 srs_error_t SrsRawAacStream::mux_sequence_header(SrsRawAacStreamCodec* codec, string& sh)
 {
     srs_error_t err = srs_success;
-    char samplingFrequencyIndex = codec->sampling_frequency_index;
 
     // only support aac profile 1-4.
     if (codec->aac_object == SrsAacObjectTypeReserved) {
@@ -447,9 +446,10 @@ srs_error_t SrsRawAacStream::mux_sequence_header(SrsRawAacStreamCodec* codec, st
     
     SrsAacObjectType audioObjectType = codec->aac_object;
     char channelConfiguration = codec->channel_configuration;
-    
-    if (samplingFrequencyIndex >= 16) {
-        samplingFrequencyIndex = 4;//default 44100
+
+    char samplingFrequencyIndex = codec->sampling_frequency_index;
+    if (samplingFrequencyIndex >= SrsAAcSampleRateNumbers) {
+        samplingFrequencyIndex = 4; // Default to 44100
     }
 
     char chs[2];
diff --git a/trunk/src/protocol/srs_raw_avc.hpp b/trunk/src/protocol/srs_raw_avc.hpp
index fc6b00f32..de81bf2ad 100644
--- a/trunk/src/protocol/srs_raw_avc.hpp
+++ b/trunk/src/protocol/srs_raw_avc.hpp
@@ -30,11 +30,6 @@
 
 #include <srs_kernel_codec.hpp>
 
-static const int mpeg4audio_sample_rates[16] = {
-    96000, 88200, 64000, 48000, 44100, 32000,
-    24000, 22050, 16000, 12000, 11025, 8000, 7350
-};
-
 class SrsBuffer;
 
 // The raw h.264 stream, in annexb.
diff --git a/trunk/src/srt/srt_to_rtmp.cpp b/trunk/src/srt/srt_to_rtmp.cpp
index 6cc52fde6..c01477fb9 100644
--- a/trunk/src/srt/srt_to_rtmp.cpp
+++ b/trunk/src/srt/srt_to_rtmp.cpp
@@ -520,9 +520,10 @@ srs_error_t rtmp_client::on_ts_video(std::shared_ptr<SrsBuffer> avs_ptr, uint64_
 int rtmp_client::get_sample_rate(char sample_index) {
     int sample_rate = 44100;
 
-    if ((sample_index >= 0) && (sample_index < 16)) {
-        sample_rate = mpeg4audio_sample_rates[sample_index];
+    if ((sample_index >= 0) && (sample_index < SrsAAcSampleRateNumbers)) {
+        sample_rate = srs_aac_srates[(uint8_t)sample_index];
     }
+
     return sample_rate;
 }