diff --git a/src/AVDecoder.cpp b/src/AVDecoder.cpp
index f8183a04..8aa40ab8 100644
--- a/src/AVDecoder.cpp
+++ b/src/AVDecoder.cpp
@@ -54,6 +54,32 @@ AVCodecContext* AVDecoder::codecContext() const
     return d_func().codec_ctx;
 }
 
+void AVDecoder::setLowResolution(int lowres)
+{
+    d_func().low_resolution = lowres;
+}
+
+int AVDecoder::lowResolution() const
+{
+    return d_func().low_resolution;
+}
+
+void AVDecoder::setDecodeThreads(int threads)
+{
+    DPTR_D(AVDecoder);
+    d.threads = threads > 0 ? threads : av_cpu_count();
+}
+
+int AVDecoder::decodeThreads() const
+{
+    return d_func().threads;
+}
+
+void AVDecoder::setThreadSlice(bool s)
+{
+    d_func().thread_slice = s;
+}
+
 bool AVDecoder::isAvailable() const
 {
     return d_func().codec_ctx != 0;
@@ -61,6 +87,21 @@ bool AVDecoder::isAvailable() const
 
 bool AVDecoder::prepare()
 {
+    DPTR_D(AVDecoder);
+    if (!d.codec_ctx) {
+        qWarning("call this after AVCodecContext is set!");
+        return false;
+    }
+    qDebug("Decoding threads count: %d", d.threads);
+    d.codec_ctx->thread_count = d.threads;
+    if (d.threads > 1)
+        d.codec_ctx->thread_type = d.thread_slice ? FF_THREAD_SLICE : FF_THREAD_FRAME;
+    else
+        d.codec_ctx->thread_type = 0; //FF_THREAD_FRAME:1, FF_THREAD_SLICE:2
+
+    //? !CODEC_ID_H264 && !CODEC_ID_VP8
+    d.codec_ctx->lowres = d.low_resolution;
+
     return true;
 }
 
diff --git a/src/AVDemuxer.cpp b/src/AVDemuxer.cpp
index f0fc35a2..47867abc 100644
--- a/src/AVDemuxer.cpp
+++ b/src/AVDemuxer.cpp
@@ -727,13 +727,6 @@ bool AVDemuxer::findAVCodec()
         if (type == AVMEDIA_TYPE_VIDEO && video_stream < 0) {
             video_stream = i;
             v_codec_context = format_context->streams[video_stream]->codec;
-            //if !vaapi
-            if (v_codec_context->codec_id == CODEC_ID_H264) {
-                v_codec_context->thread_type = FF_THREAD_FRAME; //FF_THREAD_SLICE;
-                v_codec_context->thread_count = QThread::idealThreadCount();
-            } else {
-                //v_codec_context->lowres = 0;
-            }
         } else if (type == AVMEDIA_TYPE_AUDIO && audio_stream < 0) {
             audio_stream = i;
             a_codec_context = format_context->streams[audio_stream]->codec;
diff --git a/src/QtAV/AVDecoder.h b/src/QtAV/AVDecoder.h
index 4524579c..5397a385 100644
--- a/src/QtAV/AVDecoder.h
+++ b/src/QtAV/AVDecoder.h
@@ -40,6 +40,13 @@ public:
     void flush();
     void setCodecContext(AVCodecContext* codecCtx); //protected
     AVCodecContext* codecContext() const;
+    //? low resolution decoding, 0: normal, 1-> 1/2 size, 2->1/4 size
+    void setLowResolution(int lowres);
+    int lowResolution() const;
+    // 0: auto detect by av_cpu_count()
+    void setDecodeThreads(int threads);
+    int decodeThreads() const;
+    void setThreadSlice(bool s);
     /*not available if AVCodecContext == 0*/
     bool isAvailable() const;
     virtual bool prepare(); //if resampler or image converter set, call it
diff --git a/src/QtAV/QtAV_Compat.h b/src/QtAV/QtAV_Compat.h
index 0a8dbe47..4f22b7eb 100644
--- a/src/QtAV/QtAV_Compat.h
+++ b/src/QtAV/QtAV_Compat.h
@@ -33,6 +33,7 @@ extern "C"
 #include <libavcodec/avcodec.h>
 #include <libavutil/avutil.h>
 #include <libavutil/mathematics.h> //AV_ROUND_UP, av_rescale_rnd for libav
+#include <libavutil/cpu.h>
 #include <libavutil/error.h>
 #include <libavutil/opt.h>
 #include <libavutil/pixdesc.h>
diff --git a/src/QtAV/VideoDecoder.h b/src/QtAV/VideoDecoder.h
index 6598a863..6d2074ab 100644
--- a/src/QtAV/VideoDecoder.h
+++ b/src/QtAV/VideoDecoder.h
@@ -42,6 +42,7 @@ public:
     VideoDecoder();
     virtual ~VideoDecoder();
     //virtual bool prepare();
+    virtual bool prepare();
     virtual bool decode(const QByteArray &encoded);
     //TODO: new api: originalVideoSize()(inSize()), decodedVideoSize()(outSize())
     //size: the decoded(actually then resized in ImageConverter) frame size
diff --git a/src/QtAV/private/AVDecoder_p.h b/src/QtAV/private/AVDecoder_p.h
index 6107eb89..15d22637 100644
--- a/src/QtAV/private/AVDecoder_p.h
+++ b/src/QtAV/private/AVDecoder_p.h
@@ -33,8 +33,12 @@ class Q_EXPORT AVDecoderPrivate : public DPtrPrivate<AVDecoder>
 public:
     AVDecoderPrivate():
         codec_ctx(0)
+      , available(true)
       , frame(0)
       , got_frame_ptr(0)
+      , threads(av_cpu_count())
+      , thread_slice(1)
+      , low_resolution(0)
     {
         frame = avcodec_alloc_frame();
     }
@@ -46,10 +50,14 @@ public:
     }
 
     AVCodecContext *codec_ctx; //set once and not change
+    bool available;
     AVFrame *frame; //set once and not change
     QByteArray decoded;
     int got_frame_ptr;
     QMutex mutex;
+    int threads;
+    bool thread_slice;
+    int low_resolution;
 };
 
 } //namespace QtAV
diff --git a/src/VideoDecoder.cpp b/src/VideoDecoder.cpp
index 2d120142..d3eb2520 100644
--- a/src/VideoDecoder.cpp
+++ b/src/VideoDecoder.cpp
@@ -53,6 +53,11 @@ VideoDecoder::~VideoDecoder()
 {
 }
 
+bool VideoDecoder::prepare()
+{
+    return AVDecoder::prepare();
+}
+
 //TODO: use ipp, cuda decode and yuv functions. is sws_scale necessary?
 bool VideoDecoder::decode(const QByteArray &encoded)
 {