diff --git a/src/AvTranscoder/data/decoded/AudioFrame.hpp b/src/AvTranscoder/data/decoded/AudioFrame.hpp
index f3a89a17..132d8224 100644
--- a/src/AvTranscoder/data/decoded/AudioFrame.hpp
+++ b/src/AvTranscoder/data/decoded/AudioFrame.hpp
@@ -66,7 +66,16 @@ class AvExport AudioFrame : public Frame
     void assign(const unsigned char* ptrValue);
 
 private:
+    /**
+     * @brief Allocate the audio buffer of the frame.
+     */
     void allocateAVSample(const AudioFrameDesc& ref);
+
+    /**
+     * @note To allocate new audio buffer if needed.
+     * @see allocateAVSample
+     */
+    friend class AudioGenerator;
 };
 }
 
diff --git a/src/AvTranscoder/data/decoded/Frame.hpp b/src/AvTranscoder/data/decoded/Frame.hpp
index 58a72a3f..aa3e45b1 100644
--- a/src/AvTranscoder/data/decoded/Frame.hpp
+++ b/src/AvTranscoder/data/decoded/Frame.hpp
@@ -18,6 +18,7 @@ class AvExport Frame
 public:
     /**
      * @brief Allocate an empty frame.
+     * @warn This only allocates the AVFrame itself, not the data buffers.
      */
     Frame();
 
diff --git a/src/AvTranscoder/data/decoded/VideoFrame.hpp b/src/AvTranscoder/data/decoded/VideoFrame.hpp
index ae9e22f9..eeea4b09 100644
--- a/src/AvTranscoder/data/decoded/VideoFrame.hpp
+++ b/src/AvTranscoder/data/decoded/VideoFrame.hpp
@@ -66,7 +66,16 @@ class AvExport VideoFrame : public Frame
     void assign(const unsigned char* ptrValue);
 
 private:
+    /**
+     * @brief Allocate the image buffer of the frame.
+     */
     void allocateAVPicture(const VideoFrameDesc& desc);
+
+    /**
+     * @note To allocate new image buffer if needed.
+     * @see allocateAVPicture
+     */
+    friend class VideoGenerator;
 };
 }
 
diff --git a/src/AvTranscoder/decoder/AudioDecoder.cpp b/src/AvTranscoder/decoder/AudioDecoder.cpp
index 9c8695fd..3b20e8bc 100644
--- a/src/AvTranscoder/decoder/AudioDecoder.cpp
+++ b/src/AvTranscoder/decoder/AudioDecoder.cpp
@@ -87,13 +87,8 @@ bool AudioDecoder::decodeNextFrame(Frame& frameBuffer)
     {
         CodedData data;
 
+        // reading
         const bool nextPacketRead = _inputStream->readNextPacket(data);
-        // if error or end of file
-        if(!nextPacketRead && !decodeNextFrame)
-        {
-            data.clear();
-            return false;
-        }
 
         // decoding
         // @note could be called several times to return the remaining frames (last call with an empty packet)
@@ -110,6 +105,13 @@ bool AudioDecoder::decodeNextFrame(Frame& frameBuffer)
             decodeNextFrame = false;
         else
             decodeNextFrame = true;
+
+        // if no frame read and decompressed
+        if(!nextPacketRead && !decodeNextFrame)
+        {
+            data.clear();
+            return false;
+        }
     }
     return decodeNextFrame;
 }
diff --git a/src/AvTranscoder/decoder/AudioGenerator.cpp b/src/AvTranscoder/decoder/AudioGenerator.cpp
index a50611bb..297ee009 100644
--- a/src/AvTranscoder/decoder/AudioGenerator.cpp
+++ b/src/AvTranscoder/decoder/AudioGenerator.cpp
@@ -7,37 +7,28 @@
 namespace avtranscoder
 {
 
-AudioGenerator::AudioGenerator()
+AudioGenerator::AudioGenerator(const AudioFrameDesc& frameDesc)
     : _inputFrame(NULL)
     , _silent(NULL)
+    , _frameDesc(frameDesc)
 {
 }
 
-AudioGenerator::AudioGenerator(const AudioGenerator& audioGenerator)
-    : _inputFrame(NULL)
-    , _silent(NULL)
-{
-}
-
-AudioGenerator& AudioGenerator::operator=(const AudioGenerator& audioGenerator)
-{
-    _inputFrame = NULL;
-    _silent = NULL;
-    return *this;
-}
-
 AudioGenerator::~AudioGenerator()
 {
     delete _silent;
 }
 
-void AudioGenerator::setNextFrame(Frame& inputFrame)
-{
-    _inputFrame = &inputFrame;
-}
-
 bool AudioGenerator::decodeNextFrame(Frame& frameBuffer)
 {
+    // check the given frame
+    if(!frameBuffer.isAudioFrame())
+    {
+        LOG_WARN("The given frame is not a valid audio frame: allocate a new AVSample to put generated data into it.");
+        frameBuffer.clear();
+        static_cast<AudioFrame&>(frameBuffer).allocateAVSample(_frameDesc);
+    }
+
     // Check channel layout of the given frame to be able to copy audio data to it.
     // @see Frame.copyData method
     if(frameBuffer.getAVFrame().channel_layout == 0)
diff --git a/src/AvTranscoder/decoder/AudioGenerator.hpp b/src/AvTranscoder/decoder/AudioGenerator.hpp
index 5c5631ad..e12b2eba 100644
--- a/src/AvTranscoder/decoder/AudioGenerator.hpp
+++ b/src/AvTranscoder/decoder/AudioGenerator.hpp
@@ -9,21 +9,24 @@ namespace avtranscoder
 
 class AvExport AudioGenerator : public IDecoder
 {
-public:
-    AudioGenerator();
-    AudioGenerator(const AudioGenerator& audioGenerator);
+private:
     AudioGenerator& operator=(const AudioGenerator& audioGenerator);
+    AudioGenerator(const AudioGenerator& audioGenerator);
+
+public:
+    AudioGenerator(const AudioFrameDesc& frameDesc);
 
     ~AudioGenerator();
 
     bool decodeNextFrame(Frame& frameBuffer);
     bool decodeNextFrame(Frame& frameBuffer, const size_t subStreamIndex);
 
-    void setNextFrame(Frame& inputFrame);
+    void setNextFrame(Frame& inputFrame) { _inputFrame = &inputFrame; }
 
 private:
     Frame* _inputFrame;  ///< Has link (no ownership)
     AudioFrame* _silent; ///< The generated silent (has ownership)
+    const AudioFrameDesc _frameDesc; ///< The description of the silence (sampleRate, channels...)
 };
 }
 
diff --git a/src/AvTranscoder/decoder/IDecoder.hpp b/src/AvTranscoder/decoder/IDecoder.hpp
index c9af9148..a373a9be 100644
--- a/src/AvTranscoder/decoder/IDecoder.hpp
+++ b/src/AvTranscoder/decoder/IDecoder.hpp
@@ -23,6 +23,9 @@ class AvExport IDecoder
     /**
      * @brief Decode next frame
      * @param frameBuffer: the frame decoded
+     * @warn the frameBuffer reference belongs to the decoder and is valid only until the
+     * next call to this function or until closing or flushing the
+     * decoder. The caller may not write to it.
      * @return status of decoding
      */
     virtual bool decodeNextFrame(Frame& frameBuffer) = 0;
diff --git a/src/AvTranscoder/decoder/VideoDecoder.cpp b/src/AvTranscoder/decoder/VideoDecoder.cpp
index 5affcb56..51363466 100644
--- a/src/AvTranscoder/decoder/VideoDecoder.cpp
+++ b/src/AvTranscoder/decoder/VideoDecoder.cpp
@@ -85,13 +85,8 @@ bool VideoDecoder::decodeNextFrame(Frame& frameBuffer)
     {
         CodedData data;
 
+        // reading
         const bool nextPacketRead = _inputStream->readNextPacket(data);
-        // if error or end of file
-        if(!nextPacketRead && !decodeNextFrame)
-        {
-            data.clear();
-            return false;
-        }
 
         // decoding
         // @note could be called several times to return the remaining frames (last call with an empty packet)
@@ -108,6 +103,13 @@ bool VideoDecoder::decodeNextFrame(Frame& frameBuffer)
             decodeNextFrame = false;
         else
             decodeNextFrame = true;
+
+        // if no frame read and decompressed
+        if(!nextPacketRead && !decodeNextFrame)
+        {
+            data.clear();
+            return false;
+        }
     }
     return decodeNextFrame;
 }
diff --git a/src/AvTranscoder/decoder/VideoGenerator.cpp b/src/AvTranscoder/decoder/VideoGenerator.cpp
index 32092077..0d35df0e 100644
--- a/src/AvTranscoder/decoder/VideoGenerator.cpp
+++ b/src/AvTranscoder/decoder/VideoGenerator.cpp
@@ -8,45 +8,28 @@
 namespace avtranscoder
 {
 
-VideoGenerator::VideoGenerator()
+VideoGenerator::VideoGenerator(const VideoFrameDesc& frameDesc)
     : _inputFrame(NULL)
     , _blackImage(NULL)
-    , _frameDesc()
+    , _frameDesc(frameDesc)
 {
 }
 
-VideoGenerator::VideoGenerator(const VideoGenerator& videoGenerator)
-    : _inputFrame(NULL)
-    , _blackImage(NULL)
-    , _frameDesc(videoGenerator.getVideoFrameDesc())
-{
-}
-
-VideoGenerator& VideoGenerator::operator=(const VideoGenerator& videoGenerator)
-{
-    _inputFrame = NULL;
-    _blackImage = NULL;
-    _frameDesc = videoGenerator.getVideoFrameDesc();
-    return *this;
-}
-
 VideoGenerator::~VideoGenerator()
 {
     delete _blackImage;
 }
 
-void VideoGenerator::setVideoFrameDesc(const VideoFrameDesc& frameDesc)
-{
-    _frameDesc = frameDesc;
-}
-
-void VideoGenerator::setNextFrame(Frame& inputFrame)
-{
-    _inputFrame = &inputFrame;
-}
-
 bool VideoGenerator::decodeNextFrame(Frame& frameBuffer)
 {
+    // check the given frame
+    if(!frameBuffer.isVideoFrame())
+    {
+        LOG_WARN("The given frame is not a valid video frame: allocate a new AVPicture to put generated data into it.");
+        frameBuffer.clear();
+        static_cast<VideoFrame&>(frameBuffer).allocateAVPicture(_frameDesc);
+    }
+
     // Generate black image
     if(!_inputFrame)
     {
diff --git a/src/AvTranscoder/decoder/VideoGenerator.hpp b/src/AvTranscoder/decoder/VideoGenerator.hpp
index 888c2c3c..b6a7a556 100644
--- a/src/AvTranscoder/decoder/VideoGenerator.hpp
+++ b/src/AvTranscoder/decoder/VideoGenerator.hpp
@@ -9,25 +9,24 @@ namespace avtranscoder
 
 class AvExport VideoGenerator : public IDecoder
 {
-public:
-    VideoGenerator();
+private:
     VideoGenerator(const VideoGenerator& videoGenerator);
     VideoGenerator& operator=(const VideoGenerator& videoGenerator);
 
+public:
+    VideoGenerator(const VideoFrameDesc& frameDesc);
+
     ~VideoGenerator();
 
     bool decodeNextFrame(Frame& frameBuffer);
     bool decodeNextFrame(Frame& frameBuffer, const size_t channelIndex);
 
-    const VideoFrameDesc& getVideoFrameDesc() const { return _frameDesc; }
-    void setVideoFrameDesc(const VideoFrameDesc& frameDesc);
-
-    void setNextFrame(Frame& inputFrame);
+    void setNextFrame(Frame& inputFrame) { _inputFrame = &inputFrame; }
 
 private:
     Frame* _inputFrame;        ///< A frame given from outside (has link, no ownership)
     VideoFrame* _blackImage;   ///< The generated black image (has ownership)
-    VideoFrameDesc _frameDesc; ///< The description of the black image (width, height...)
+    const VideoFrameDesc _frameDesc; ///< The description of the black image (width, height...)
 };
 }
 
diff --git a/src/AvTranscoder/file/InputFile.cpp b/src/AvTranscoder/file/InputFile.cpp
index 93dcaddb..e20ffd84 100644
--- a/src/AvTranscoder/file/InputFile.cpp
+++ b/src/AvTranscoder/file/InputFile.cpp
@@ -68,7 +68,7 @@ bool InputFile::readNextPacket(CodedData& data, const size_t streamIndex)
         const int ret = av_read_frame(&_formatContext.getAVFormatContext(), &data.getAVPacket());
         if(ret < 0) // error or end of file
         {
-            LOG_INFO("No more data to read on file '" << _filename << "' for stream " << streamIndex)
+            LOG_INFO("Stop reading the next frame of file '" << _filename << "', stream " << streamIndex << " (" << getDescriptionFromErrorCode(ret) << ")")
             return false;
         }
 
diff --git a/src/AvTranscoder/reader/AudioReader.cpp b/src/AvTranscoder/reader/AudioReader.cpp
index 9495d8b5..b7b487c4 100644
--- a/src/AvTranscoder/reader/AudioReader.cpp
+++ b/src/AvTranscoder/reader/AudioReader.cpp
@@ -42,9 +42,10 @@ void AudioReader::init()
     // setup decoder
     _decoder = new AudioDecoder(_inputFile->getStream(_streamIndex));
     _decoder->setupDecoder();
+    _currentDecoder = _decoder;
 
     // generator
-    _generator = new AudioGenerator();
+    _generator = new AudioGenerator(_inputFile->getStream(_streamIndex).getAudioCodec().getAudioFrameDesc());
 
     // create transform
     _transform = new AudioTransform();
diff --git a/src/AvTranscoder/reader/IReader.cpp b/src/AvTranscoder/reader/IReader.cpp
index 76bed7ff..c950571e 100644
--- a/src/AvTranscoder/reader/IReader.cpp
+++ b/src/AvTranscoder/reader/IReader.cpp
@@ -9,6 +9,8 @@ IReader::IReader(const std::string& filename, const size_t streamIndex, const in
     : _inputFile(NULL)
     , _streamProperties(NULL)
     , _decoder(NULL)
+    , _generator(NULL)
+    , _currentDecoder(NULL)
     , _srcFrame(NULL)
     , _dstFrame(NULL)
     , _transform(NULL)
@@ -25,6 +27,8 @@ IReader::IReader(InputFile& inputFile, const size_t streamIndex, const int chann
     : _inputFile(&inputFile)
     , _streamProperties(NULL)
     , _decoder(NULL)
+    , _generator(NULL)
+    , _currentDecoder(NULL)
     , _srcFrame(NULL)
     , _dstFrame(NULL)
     , _transform(NULL)
@@ -54,8 +58,7 @@ Frame* IReader::readPrevFrame()
 
 Frame* IReader::readFrameAt(const size_t frame)
 {
-    assert(_decoder != NULL);
-    assert(_generator != NULL);
+    assert(_currentDecoder != NULL);
     assert(_transform != NULL);
     assert(_srcFrame != NULL);
     assert(_dstFrame != NULL);
@@ -70,16 +73,17 @@ Frame* IReader::readFrameAt(const size_t frame)
     // decode
     bool decodingStatus = false;
     if(_channelIndex != -1)
-        decodingStatus = _decoder->decodeNextFrame(*_srcFrame, _channelIndex);
+        decodingStatus = _currentDecoder->decodeNextFrame(*_srcFrame, _channelIndex);
     else
-        decodingStatus = _decoder->decodeNextFrame(*_srcFrame);
+        decodingStatus = _currentDecoder->decodeNextFrame(*_srcFrame);
     // if decoding failed
     if(!decodingStatus)
     {
         // generate data (ie silence or black)
         if(_continueWithGenerator)
         {
-           _generator->decodeNextFrame(*_srcFrame);
+            _currentDecoder = _generator;
+            return readFrameAt(frame);
         }
         // or return NULL
         else
diff --git a/src/AvTranscoder/reader/IReader.hpp b/src/AvTranscoder/reader/IReader.hpp
index 8d53b647..696e38d5 100644
--- a/src/AvTranscoder/reader/IReader.hpp
+++ b/src/AvTranscoder/reader/IReader.hpp
@@ -68,6 +68,7 @@ class AvExport IReader
     const StreamProperties* _streamProperties;
     IDecoder* _decoder;
     IDecoder* _generator;
+    IDecoder* _currentDecoder; ///< Link to _inputDecoder or _generator
 
     Frame* _srcFrame;
     Frame* _dstFrame;
diff --git a/src/AvTranscoder/reader/VideoReader.cpp b/src/AvTranscoder/reader/VideoReader.cpp
index 53fc00f1..304a5d22 100644
--- a/src/AvTranscoder/reader/VideoReader.cpp
+++ b/src/AvTranscoder/reader/VideoReader.cpp
@@ -41,11 +41,10 @@ void VideoReader::init()
     // setup decoder
     _decoder = new VideoDecoder(_inputFile->getStream(_streamIndex));
     _decoder->setupDecoder();
+    _currentDecoder = _decoder;
 
     // generator
-    VideoGenerator* generator = new VideoGenerator();
-    generator->setVideoFrameDesc(_inputFile->getStream(_streamIndex).getVideoCodec().getVideoFrameDesc());
-    _generator = generator;
+    _generator = new VideoGenerator(_inputFile->getStream(_streamIndex).getVideoCodec().getVideoFrameDesc());
 
     // create transform
     _transform = new VideoTransform();
diff --git a/src/AvTranscoder/transcoder/StreamTranscoder.cpp b/src/AvTranscoder/transcoder/StreamTranscoder.cpp
index c88870b5..67f3e8a4 100644
--- a/src/AvTranscoder/transcoder/StreamTranscoder.cpp
+++ b/src/AvTranscoder/transcoder/StreamTranscoder.cpp
@@ -51,9 +51,7 @@ StreamTranscoder::StreamTranscoder(IInputStream& inputStream, IOutputFile& outpu
                 VideoFrameDesc inputFrameDesc(_inputStream->getVideoCodec().getVideoFrameDesc());
 
                 // generator decoder
-                VideoGenerator* generatorVideo = new VideoGenerator();
-                generatorVideo->setVideoFrameDesc(inputFrameDesc);
-                _generator = generatorVideo;
+                _generator = new VideoGenerator(inputFrameDesc);
 
                 // buffers to process
                 _sourceBuffer = new VideoFrame(inputFrameDesc);
@@ -88,8 +86,7 @@ StreamTranscoder::StreamTranscoder(IInputStream& inputStream, IOutputFile& outpu
                 AudioFrameDesc inputFrameDesc(_inputStream->getAudioCodec().getAudioFrameDesc());
 
                 // generator decoder
-                AudioGenerator* generatorAudio = new AudioGenerator();
-                _generator = generatorAudio;
+                _generator = new AudioGenerator(inputFrameDesc);
 
                 // buffers to process
                 _sourceBuffer = new AudioFrame(inputFrameDesc);
@@ -173,9 +170,7 @@ StreamTranscoder::StreamTranscoder(IInputStream& inputStream, IOutputFile& outpu
             _transform = new VideoTransform();
 
             // generator decoder
-            VideoGenerator* generatorVideo = new VideoGenerator();
-            generatorVideo->setVideoFrameDesc(outputVideo->getVideoCodec().getVideoFrameDesc());
-            _generator = generatorVideo;
+            _generator = new VideoGenerator(outputVideo->getVideoCodec().getVideoFrameDesc());
 
             break;
         }
@@ -218,8 +213,7 @@ StreamTranscoder::StreamTranscoder(IInputStream& inputStream, IOutputFile& outpu
             _transform = new AudioTransform();
 
             // generator decoder
-            AudioGenerator* generatorAudio = new AudioGenerator();
-            _generator = generatorAudio;
+            _generator = new AudioGenerator(outputFrameDesc);
 
             break;
         }
@@ -249,11 +243,9 @@ StreamTranscoder::StreamTranscoder(const ICodec& inputCodec, IOutputFile& output
 {
     if(profile.find(constants::avProfileType)->second == constants::avProfileTypeVideo)
     {
-        // generator decoder
-        VideoGenerator* generatorVideo = new VideoGenerator();
         const VideoCodec& inputVideoCodec = static_cast<const VideoCodec&>(inputCodec);
-        generatorVideo->setVideoFrameDesc(inputVideoCodec.getVideoFrameDesc());
-        _generator = generatorVideo;
+        // generator decoder
+        _generator = new VideoGenerator(inputVideoCodec.getVideoFrameDesc());
         _currentDecoder = _generator;
 
         // filter
@@ -279,10 +271,9 @@ StreamTranscoder::StreamTranscoder(const ICodec& inputCodec, IOutputFile& output
     }
     else if(profile.find(constants::avProfileType)->second == constants::avProfileTypeAudio)
     {
-        // generator decoder
-        AudioGenerator* generatorAudio = new AudioGenerator();
         const AudioCodec& inputAudioCodec = static_cast<const AudioCodec&>(inputCodec);
-        _generator = generatorAudio;
+        // generator decoder
+        _generator = new AudioGenerator(inputAudioCodec.getAudioFrameDesc());
         _currentDecoder = _generator;
 
         // filter
@@ -483,12 +474,12 @@ bool StreamTranscoder::processTranscode(const int subStreamIndex)
     else
         decodingStatus = _currentDecoder->decodeNextFrame(*_sourceBuffer, subStreamIndex);
 
-    LOG_DEBUG("Filtering")
-    _filterGraph->process(*_sourceBuffer);
-
     CodedData data;
     if(decodingStatus)
     {
+        LOG_DEBUG("Filtering")
+        _filterGraph->process(*_sourceBuffer);
+
         LOG_DEBUG("Convert")
         _transform->convert(*_sourceBuffer, *_frameBuffer);