diff --git a/data/formats/avi/Demuxer.h b/data/formats/avi/Demuxer.h
index cc8f791..72e7d8d 100644
--- a/data/formats/avi/Demuxer.h
+++ b/data/formats/avi/Demuxer.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "structs.h"
+#include <iostream>
 
 // https://docs.microsoft.com/en-us/previous-versions//ms779636(v=vs.85)?redirectedfrom=MSDN
 namespace AVI {
@@ -12,8 +13,7 @@ namespace AVI {
 		bool valid = true;
 		AVITypeHeader riff;
 		AVITypeHeader hdrl;
-		AVICommonHeader avih;
-		AVIMainHeader main_hdr;
+		AVIMainHeader avih;
 
 		struct State {
 
@@ -21,7 +21,7 @@ namespace AVI {
 
 			struct Video {
 				uint32_t streamID;
-				BitMapInfoHeader fmt;
+				BitMapInfo fmt;
 			} video;
 
 			struct Audio {
@@ -49,14 +49,13 @@ namespace AVI {
 
 			read(avih);
 			if (memcmp(avih.fourcc, "avih", 4) != 0)	{valid = false; return;}
-			if (avih.length != sizeof(main_hdr))		{valid = false; return;}
+			if (avih.cb != 56)							{valid = false; return;}
 
-			read(main_hdr);
 
-			uint32_t posOfStreamStart = pos;
 
-			for (uint32_t i = 0; i < main_hdr.streams; ++i) {
+			for (uint32_t i = 0; i < avih.streams; ++i) {
 
+				uint32_t posOfStreamStart = pos;
 				bool curStreamIsVideo = false;
 
 				AVITypeHeader strl;
@@ -64,32 +63,30 @@ namespace AVI {
 				if (memcmp(strl.fourcc, "LIST", 4) != 0)	{valid = false; return;}
 				if (memcmp(strl.type,   "strl", 4) != 0)	{valid = false; return;}
 
-				AVICommonHeader strh;
+				AVIStreamHeader strh;
 				read(strh);
 				if (memcmp(strh.fourcc,   "strh", 4) != 0)	{valid = false; return;}
 
-				AVIStreamHeader stream_hdr;
-				read(stream_hdr);
-				if			(memcmp(stream_hdr.type, "vids", 4) == 0) {
+				if			(memcmp(strh.type, "vids", 4) == 0) {
 					state.video.streamID = i;
-					state.streamHeaders[i] = stream_hdr;
+					state.streamHeaders[i] = strh;
 					curStreamIsVideo = true;
-				} else if	(memcmp(stream_hdr.type, "auds", 4) == 0) {
+				} else if	(memcmp(strh.type, "auds", 4) == 0) {
 					state.audio.streamID = i;
-					state.streamHeaders[i] = stream_hdr;
+					state.streamHeaders[i] = strh;
 				} else {
 					valid = false; return;
 				}
 
-				AVICommonHeader strf;
-				read(strf);
+				// ????
+				uint8_t xx[8];
+				read(xx);
+
+				// strf, depends on type (audio/video)
 				if (curStreamIsVideo) {
-					BitMapInfoHeader bmih;
-					read(bmih);
-					state.video.fmt = bmih;
+					read(state.video.fmt);		// BitmapInfoHeader
 				} else {
-					WaveFormat wf;
-					read(state.audio.fmt);
+					read(state.audio.fmt);		// WaveFormatEx
 				}
 
 				// seek to the next stream
@@ -97,6 +94,13 @@ namespace AVI {
 
 			}
 
+			dumpState();
+
+			uint8_t tmp[128];
+			read(tmp);
+
+			seek(pos-4);
+
 			AVITypeHeader movi;
 			state.moviInfo.offset = pos;
 			read(movi);
@@ -124,10 +128,9 @@ namespace AVI {
 
 
 			//seek(state.streamHeaders[state.video.streamID].start);
-			AVICommonHeader chead;
-			read(chead);
+			//AVICommonHeader chead;
+			//read(chead);
 
-			printf("nn");
 
 		}
 
@@ -153,6 +156,15 @@ namespace AVI {
 			pos += size;
 		}
 
+
+		void dumpState() {
+
+			std::cout << "video @" << state.video.streamID << ": " << state.video.fmt.bmi_header.biWidth << "x" << state.video.fmt.bmi_header.biHeight << std::endl;
+			std::cout << "audio @" << state.audio.streamID << ": " << state.audio.fmt.channels << " channels @ " << state.audio.fmt.samples_per_sec << " Hz" << std::endl;
+
+
+		}
+
 	};
 
 }
diff --git a/data/formats/avi/structs.h b/data/formats/avi/structs.h
index 84fa208..a98dfe1 100644
--- a/data/formats/avi/structs.h
+++ b/data/formats/avi/structs.h
@@ -2,10 +2,10 @@
 
 typedef uint8_t FOURCC[4];
 
-struct AVICommonHeader {
-	FOURCC fourcc;
-	uint32_t length;
-};
+//struct AVICommonHeader {
+//	FOURCC fourcc;
+//	uint32_t length;
+//};
 
 struct AVITypeHeader {
 	FOURCC fourcc;
@@ -14,6 +14,8 @@ struct AVITypeHeader {
 };
 
 struct AVIMainHeader {
+	FOURCC fourcc;
+	uint32_t cb;
 	uint32_t ms_per_frame;
 	uint32_t max_bytes_per_sec;
 	uint32_t padding_granularity;
@@ -27,9 +29,16 @@ struct AVIMainHeader {
 	uint32_t reserved[4];
 };
 
+struct AVIRect {
+	uint16_t left;
+	uint16_t top;
+	uint16_t right;
+	uint16_t bottom;
+};
+
 struct AVIStreamHeader {
-	//FOURCC fourcc;
-	//uint32_t length;
+	FOURCC fourcc;
+	uint32_t cb;
 	FOURCC type;
 	FOURCC fcc_handler;
 	uint32_t flags;
@@ -43,12 +52,7 @@ struct AVIStreamHeader {
 	uint32_t suggested_buffer_size;
 	uint32_t quality;
 	uint32_t sample_size;
-	struct {
-		uint16_t left;
-		uint16_t top;
-		uint16_t right;
-		uint16_t bottom;
-	} rcFrame;
+	AVIRect rcFrame;
 };
 
 struct BitMapInfoHeader {
diff --git a/ext/sd/main.cpp b/ext/sd/main.cpp
index 3c1e6a6..92456b2 100644
--- a/ext/sd/main.cpp
+++ b/ext/sd/main.cpp
@@ -94,7 +94,7 @@ int main(int argc, char** argv) {
 		AVI::Demuxer demux(ah);
 
 		bool valid = demux.isValid();
-		std::cout << valid << std::endl;
+		std::cout << "valid: " << valid << std::endl;
 
 		return 0;