diff --git a/src/media/media_buffer.h b/src/media/media_buffer.h
index 245e58610e45e86b3145595baea22b5aeddf2ccf..e2fcb0a8ee92b3fec2a7eb84d219e6b88c5047b1 100644
--- a/src/media/media_buffer.h
+++ b/src/media/media_buffer.h
@@ -25,7 +25,7 @@
 #include <memory>
 #include <functional>
 
-class AVFrame;
+struct AVFrame;
 
 namespace DRing {
 struct FrameBuffer; //  from dring/videomanager_interface.h
diff --git a/src/media/media_decoder.h b/src/media/media_decoder.h
index 807e8ee251860dda8eab47f8cfe174d6454d7840..5f1f82f2accd1204fc66bcdbf4416b371a7db25f 100644
--- a/src/media/media_decoder.h
+++ b/src/media/media_decoder.h
@@ -40,17 +40,17 @@
 #include <memory>
 #include <chrono>
 
-class AVCodecContext;
-class AVStream;
-class AVDictionary;
-class AVFormatContext;
-class AVCodec;
+struct AVCodecContext;
+struct AVStream;
+struct AVDictionary;
+struct AVFormatContext;
+struct AVCodec;
 enum AVMediaType;
 
 namespace ring {
 
 struct AudioFrame;
-class AudioFormat;
+struct AudioFormat;
 class RingBuffer;
 class Resampler;
 class MediaIOHandle;
diff --git a/src/media/media_filter.h b/src/media/media_filter.h
index 518a791224214f32516e4fc26fd249586ad1c1a4..b3278ef9b1e0ae9094b811bc1a8ca8ba5f8eff2f 100644
--- a/src/media/media_filter.h
+++ b/src/media/media_filter.h
@@ -28,9 +28,9 @@
 #include <string>
 #include <vector>
 
-class AVFilterContext;
-class AVFilterGraph;
-class AVFilterInOut;
+struct AVFilterContext;
+struct AVFilterGraph;
+struct AVFilterInOut;
 
 namespace ring {
 
diff --git a/src/media/media_io_handle.h b/src/media/media_io_handle.h
index 02b6e14360e835a8ba7e0466be969bc4328f06ef..ebb5d8907c058a7a8ac6bbebea8eabf7ce163118 100644
--- a/src/media/media_io_handle.h
+++ b/src/media/media_io_handle.h
@@ -28,7 +28,7 @@
 #include <vector>
 
 #ifndef AVFORMAT_AVIO_H
-class AVIOContext;
+struct AVIOContext;
 #endif
 
 typedef int(*io_readcallback)(void *opaque, uint8_t *buf, int buf_size);
diff --git a/src/media/video/video_scaler.h b/src/media/video/video_scaler.h
index d08e181bce3e28083287d5e232ed0c0525285507..8f39c03859fa069066ce96e15e4ea177bbc84b4e 100644
--- a/src/media/video/video_scaler.h
+++ b/src/media/video/video_scaler.h
@@ -25,7 +25,7 @@
 #include "noncopyable.h"
 
 
-class SwsContext;
+struct SwsContext;
 
 namespace ring { namespace video {