diff --git a/src/AvTranscoder/filter/FilterGraph.hpp b/src/AvTranscoder/filter/FilterGraph.hpp
index 4ae9274c..86a5ea4c 100644
--- a/src/AvTranscoder/filter/FilterGraph.hpp
+++ b/src/AvTranscoder/filter/FilterGraph.hpp
@@ -52,6 +52,8 @@ class AvExport FilterGraph
      *                               filter 1 -> filter 2 -> output
      *                                 |
      *                      input 2 ---|
+     * @warning the output frame must be cleared once it has been used
+     * @see the av_buffersink_get_frame function documentation
      */
     void process(const std::vector<Frame*>& inputs, Frame& output);
 
diff --git a/src/AvTranscoder/transcoder/StreamTranscoder.cpp b/src/AvTranscoder/transcoder/StreamTranscoder.cpp
index 9b72ec49..25a63d1b 100644
--- a/src/AvTranscoder/transcoder/StreamTranscoder.cpp
+++ b/src/AvTranscoder/transcoder/StreamTranscoder.cpp
@@ -550,6 +550,8 @@ bool StreamTranscoder::processTranscode()
         LOG_DEBUG("Convert")
         _transform->convert(*_filteredData, *_transformedData);
 
+        _filteredData->clear();
+
         LOG_DEBUG("Encode")
         _outputEncoder->encodeFrame(*_transformedData, data);
     }