diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6fe1ca7..7f4e5ee 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,8 +8,10 @@ function(em_file name)
             ${CMAKE_SOURCE_DIR}/decoder.cpp
             ${CMAKE_SOURCE_DIR}/${name}.cpp
             -o ${CMAKE_BINARY_DIR}/${name}.js 
-            -s WASM=0
-            -g4
+            -s FILESYSTEM=0
+            -s ENVIRONMENT=web
+            -Oz
+            --llvm-lto 1
             )
 endfunction(em_file)
 
diff --git a/decoder.cpp b/decoder.cpp
index e4c54b5..e4c7d0e 100644
--- a/decoder.cpp
+++ b/decoder.cpp
@@ -54,7 +54,7 @@ void Decoder::addFragment(const emscripten::val& array)
     uint32_t length = array["length"].as<uint32_t>();
     
     if (length < GLUE_LENGTH / 2) {
-        std::cout << "An attempt to add fragment smaller then half of the glue buffer, ignoring";
+        std::cout << "Error: an attempt to add fragment smaller then half of the glue buffer, ignoring";
         return;
     }
     uint8_t* buffer = new uint8_t[length];
@@ -117,9 +117,7 @@ emscripten::val Decoder::decode(uint32_t count)
         for (int i = 0; success < available; ++i) {
             int res = mad_frame_decode(frame, stream);
             
-            if (res == 0) {
-                ++success;
-            } else {
+            if (res != 0) {
                 if (MAD_RECOVERABLE(stream->error)) {
                     
                     std::cout << "Unexpected error during the decoding process: " << mad_stream_errorstr(stream) << std::endl;
@@ -134,14 +132,16 @@ emscripten::val Decoder::decode(uint32_t count)
             for (int j = 0; j < samplesPerFrame; ++j) {
                 for (int k = 0; k < channels; ++k) {
                     float value = mad_f_todouble(synth->pcm.samples[k][j]);
-                    chans[k].set(std::to_string(i * samplesPerFrame + j), emscripten::val(value));
+                    chans[k].set(std::to_string(success * samplesPerFrame + j), emscripten::val(value));
                 }
             }
+            ++success;
         }
         
         cachedLength -= available;
+        #if DEBUGGING
         std::cout << "Processed " << available << " frames, " << success << " successfully, last error " << mad_stream_errorstr(stream) << std::endl;
-        
+        #endif
         if (cachedLength == 0) {
             cached = false;
             prepareNextBuffer();
@@ -171,6 +171,7 @@ uint32_t Decoder::framesLeft(uint32_t max)
         mad_header ph;
         initializeProbe(probe);
         mad_header_init(&ph);
+        sampleRate = 0;
         
         while (cachedLength < max) {
             if (mad_header_decode(&ph, &probe) == 0) {
@@ -180,14 +181,24 @@ uint32_t Decoder::framesLeft(uint32_t max)
                     samplesPerFrame = MAD_NSBSAMPLES(&ph) * 32; //not sure why 32, it's in libmad source
                 } else {
                     if (sampleRate != ph.samplerate || channels != MAD_NCHANNELS(&ph) || samplesPerFrame != MAD_NSBSAMPLES(&ph) * 32) {
-                        break;
+                        if (cachedLength > 0) {
+                            #if DEBUGGING
+                            std::cout << "sample rate " << sampleRate << " -> " << ph.samplerate << std::endl;
+                            std::cout << "channels " << channels << " -> " << MAD_NCHANNELS(&ph) << std::endl;
+                            std::cout << "samples per frame " << samplesPerFrame << " -> " << MAD_NSBSAMPLES(&ph) * 32 << std::endl;
+                            #endif
+                            probe.next_frame = probe.this_frame;
+                            break;
+                        }
                     }
                 }
                 if (probe.next_frame > probe.this_frame) {
                     ++cachedLength;
                 }
             } else {
+                #if DEBUGGING
                 std::cout << "framesLeft error: " << mad_stream_errorstr(&probe) << std::endl;
+                #endif
                 if (!MAD_RECOVERABLE(probe.error)) {
                     break;
                 }
@@ -199,7 +210,9 @@ uint32_t Decoder::framesLeft(uint32_t max)
         cachedError = probe.error;
         mad_header_finish(&ph);
         mad_stream_finish(&probe);
+        #if DEBUGGING
         std::cout << cachedLength << " frames are available for decoding" << std::endl;
+        #endif
         cached = true;
     }
     
@@ -233,7 +246,9 @@ void Decoder::changeBuffer()
             std::cout << "Wrong state on switchBuffer method - onGlueHalf, aborting" << std::endl;
             break;
         case onGlueFull:
+            #if DEBUGGING
             std::cout << "Having another fragment " << pending[0].length << " bytes long" << std::endl;
+            #endif
             
             switchBuffer(pending[0].ptr, pending[0].length);
             
@@ -275,7 +290,7 @@ void Decoder::initializeProbe(mad_stream& probe)
     
     probe.buffer = stream->buffer;
     probe.bufend = stream->bufend;
-    //probe.skiplen = stream->skiplen; 
+    probe.skiplen = stream->skiplen; 
     //probe.sync = stream->sync;
     //probe.freerate = stream->freerate;
     //probe.this_frame = stream->this_frame;
@@ -295,10 +310,14 @@ void Decoder::initializeProbe(mad_stream& probe)
 
 void Decoder::switchToGlue()
 {
+    #if DEBUGGING
     std::cout << "Switching to glue" << std::endl;
+    #endif
     switchBuffer(glue, GLUE_LENGTH);
     
+    #if DEBUGGING
     std::cout << "Freeing the drained fragment" << std::endl;
+    #endif
     delete[] pending[0].ptr;
     pending.pop_front();
 }
@@ -308,7 +327,7 @@ void Decoder::switchBuffer(uint8_t* bufferPtr, uint32_t length)
     uint32_t left;
     
     if (stream->error != MAD_ERROR_BUFLEN) {
-        std::cout << "WARNING: Switching buffers while the previous one is not drained, error: " << mad_stream_errorstr(stream) << std::endl;
+        std::cout << "WARNING: Switching buffers while the previous one is not drained, last error: " << mad_stream_errorstr(stream) << std::endl;
     }
     if (stream->next_frame != NULL) {
         left = stream->bufend - stream->next_frame;