diff --git a/src/QtAV/AVDecoder.h b/src/QtAV/AVDecoder.h
index d67c1da1f..e645ceaf3 100644
--- a/src/QtAV/AVDecoder.h
+++ b/src/QtAV/AVDecoder.h
@@ -83,13 +83,13 @@ class Q_AV_EXPORT AVDecoder : public QObject
 Q_SIGNALS:
     void error(const QtAV::AVError& e); //explictly use QtAV::AVError in connection for Qt4 syntax
     void descriptionChanged();
+    virtual void codecNameChanged();
 protected:
     AVDecoder(AVDecoderPrivate& d);
     DPTR_DECLARE(AVDecoder)
     // force a codec. only used by avcodec sw decoders
     void setCodecName(const QString& name);
     QString codecName() const;
-    virtual void codecNameChanged() {}
 private:
     Q_DISABLE_COPY(AVDecoder)
     AVDecoder(); // base class, not direct create. only final class has is enough
diff --git a/src/QtAV/VideoCapture.h b/src/QtAV/VideoCapture.h
index 8af591945..a6e53602b 100644
--- a/src/QtAV/VideoCapture.h
+++ b/src/QtAV/VideoCapture.h
@@ -85,7 +85,8 @@ class Q_AV_EXPORT VideoCapture : public QObject
     void setCaptureDir(const QString& value);
     QString captureDir() const;
 public Q_SLOTS:
-    void request();
+    void capture();
+    QTAV_DEPRECATED void request();
 Q_SIGNALS:
     void requested();
     /*use it to popup a dialog for selecting dir, name etc. TODO: block avthread if not async*/
diff --git a/src/QtAV/VideoDecoder.h b/src/QtAV/VideoDecoder.h
index 93d774779..24bf86e89 100644
--- a/src/QtAV/VideoDecoder.h
+++ b/src/QtAV/VideoDecoder.h
@@ -27,7 +27,6 @@
 #include <QtAV/VideoFrame.h>
 
 class QSize;
-struct SwsContext;
 namespace QtAV {
 
 typedef int VideoDecoderId;
diff --git a/src/QtAV/private/AVDecoder_p.h b/src/QtAV/private/AVDecoder_p.h
index bde0f104c..49558abc2 100644
--- a/src/QtAV/private/AVDecoder_p.h
+++ b/src/QtAV/private/AVDecoder_p.h
@@ -24,8 +24,6 @@
 
 #include <QtCore/QByteArray>
 #include <QtCore/QHash>
-#include <QtCore/QMutex>
-#include <QtCore/QThread>
 #include "QtAV/private/AVCompat.h"
 
 namespace QtAV {
@@ -55,7 +53,6 @@ class Q_AV_PRIVATE_EXPORT AVDecoderPrivate : public DPtrPrivate<AVDecoder>
     bool available; //TODO: true only when context(and hw ctx) is ready
     bool is_open;
     int undecoded_size;
-    QMutex mutex;
     QString codec_name;
     QVariantHash options;
     AVDictionary *dict;
diff --git a/src/codec/AVDecoder.cpp b/src/codec/AVDecoder.cpp
index 347b73b36..f1f0aed28 100644
--- a/src/codec/AVDecoder.cpp
+++ b/src/codec/AVDecoder.cpp
@@ -29,15 +29,7 @@ namespace QtAV {
 AVDecoder::AVDecoder(AVDecoderPrivate &d)
     :DPTR_INIT(&d)
 {
-    class AVInitializer {
-    public:
-        AVInitializer() {
-            qDebug("avcodec_register_all");
-            avcodec_register_all();
-        }
-    };
-    static AVInitializer sAVInit;
-    Q_UNUSED(sAVInit);
+    avcodec_register_all(); // avcodec_find_decoder will always be used
 }
 
 AVDecoder::~AVDecoder()
@@ -165,7 +157,11 @@ AVCodecContext* AVDecoder::codecContext() const
 
 void AVDecoder::setCodecName(const QString &name)
 {
-    d_func().codec_name = name;
+    DPTR_D(AVDecoder);
+    if (d.codec_name == name)
+        return;
+    d.codec_name = name;
+    Q_EMIT codecNameChanged();
 }
 
 QString AVDecoder::codecName() const
@@ -224,7 +220,7 @@ void AVDecoder::setOptions(const QVariantHash &dict)
     else if (dict.contains(name().toLower()))
         opt = dict.value(name().toLower());
     else
-        return;
+        return; // TODO: set property if no name() key found?
     if (opt.type() == QVariant::Hash) {
         QVariantHash property_dict(opt.toHash());
         if (property_dict.isEmpty())
diff --git a/src/codec/audio/AudioDecoderFFmpeg.cpp b/src/codec/audio/AudioDecoderFFmpeg.cpp
index a9ec0a529..f06261fd7 100644
--- a/src/codec/audio/AudioDecoderFFmpeg.cpp
+++ b/src/codec/audio/AudioDecoderFFmpeg.cpp
@@ -66,7 +66,9 @@ class AudioDecoderFFmpegPrivate : public AudioDecoderPrivate
     AudioDecoderFFmpegPrivate()
         : AudioDecoderPrivate()
         , frame(av_frame_alloc())
-    {}
+    {
+        avcodec_register_all();
+    }
     ~AudioDecoderFFmpegPrivate() {
         if (frame) {
             av_frame_free(&frame);
diff --git a/src/codec/video/VideoDecoderFFmpegBase.h b/src/codec/video/VideoDecoderFFmpegBase.h
index 99c746893..8694af63b 100644
--- a/src/codec/video/VideoDecoderFFmpegBase.h
+++ b/src/codec/video/VideoDecoderFFmpegBase.h
@@ -49,6 +49,7 @@ class VideoDecoderFFmpegBasePrivate : public VideoDecoderPrivate
         : VideoDecoderPrivate()
         , frame(0)
     {
+        avcodec_register_all();
         frame = av_frame_alloc();
     }
     virtual ~VideoDecoderFFmpegBasePrivate() {