diff --git a/mpp/codec/dec/dummy/dummy_dec_api.c b/mpp/codec/dec/dummy/dummy_dec_api.c
index 2e335ad6..bb6ec8dc 100644
--- a/mpp/codec/dec/dummy/dummy_dec_api.c
+++ b/mpp/codec/dec/dummy/dummy_dec_api.c
@@ -16,58 +16,121 @@
 */
 #define MODULE_TAG "dummy_dec_api"
 
+#include <string.h>
+
+#include "mpp_log.h"
 
 #include "dummy_dec_api.h"
 
+#define DUMMY_DEC_FRAME_SIZE        SZ_1M
+#define DUMMY_DEC_FRAME_COUNT       16
 
-MPP_RET dummy_dec_init(void *decoder, MppParserInitCfg *init)
+typedef struct DummyDec_t {
+    MppBufSlots     slots;
+    RK_U32          task_count;
+
+    RK_U32          slots_inited;
+} DummyDec;
+
+MPP_RET dummy_dec_init(void *dec, MppParserInitCfg *cfg)
 {
-    (void)decoder;
-    (void)init;
+    if (NULL == dec) {
+        mpp_err_f("found NULL intput dec %p cfg %p\n", dec, cfg);
+        return MPP_ERR_NULL_PTR;
+    }
+
+    DummyDec *p = (DummyDec *)dec;
+    p->slots        = cfg->slots;
+    p->task_count   = cfg->task_count = 2;
+    p->slots_inited = 0;
     return MPP_OK;
 }
 
-MPP_RET dummy_dec_deinit(void *decoder)
+MPP_RET dummy_dec_deinit(void *dec)
 {
-    (void)decoder;
+    if (NULL == dec) {
+        mpp_err_f("found NULL intput\n");
+        return MPP_ERR_NULL_PTR;
+    }
     return MPP_OK;
 }
 
-MPP_RET dummy_dec_reset(void *decoder)
+MPP_RET dummy_dec_reset(void *dec)
 {
-    (void)decoder;
+    if (NULL == dec) {
+        mpp_err_f("found NULL intput\n");
+        return MPP_ERR_NULL_PTR;
+    }
     return MPP_OK;
 }
 
 
-MPP_RET dummy_dec_flush(void *decoder)
+MPP_RET dummy_dec_flush(void *dec)
 {
-    (void)decoder;
+    if (NULL == dec) {
+        mpp_err_f("found NULL intput\n");
+        return MPP_ERR_NULL_PTR;
+    }
     return MPP_OK;
 }
 
 
-MPP_RET dummy_dec_control(void *decoder, RK_S32 cmd_type, void *param)
+MPP_RET dummy_dec_control(void *dec, RK_S32 cmd_type, void *param)
 {
-    (void)decoder;
+    if (NULL == dec) {
+        mpp_err_f("found NULL intput\n");
+        return MPP_ERR_NULL_PTR;
+    }
     (void)cmd_type;
     (void)param;
     return MPP_OK;
 }
 
 
-MPP_RET dummy_dec_parse(void *decoder, MppPacket pkt, HalDecTask *task)
+MPP_RET dummy_dec_parse(void *dec, MppPacket pkt, HalDecTask *task)
 {
-    (void)decoder;
-    (void)pkt;
-    (void)task;
+    if (NULL == dec) {
+        mpp_err_f("found NULL intput\n");
+        return MPP_ERR_NULL_PTR;
+    }
+
+    DummyDec *p = (DummyDec *)dec;
+    // do packet decoding here
+
+    // set packet size
+    mpp_packet_set_size(pkt, 0);
+
+    /*
+     * set slots information
+     * 1. output index MUST be set
+     * 2. if one frame can be display, it SHOULD be set display
+     */
+    if (!p->slots_inited) {
+        mpp_buf_slot_setup(p->slots, DUMMY_DEC_FRAME_COUNT, DUMMY_DEC_FRAME_SIZE, 0);
+        p->slots_inited = 1;
+    }
+
+    RK_S32 output = -1;
+    mpp_buf_slot_get_unused(p->slots, &output);
+    mpp_buf_slot_set_display(p->slots, output);
+
+    /*
+     * setup output task
+     * 1. valid flag MUST be set if need hardware to run once
+     * 2. set output slot index
+     * 3. set reference slot index
+     */
+    task->valid     = 1;
+    task->output    = output;
+    memset(&task->refer, -1, sizeof(task->refer));
+
     return MPP_OK;
 }
 
 const MppDecParser dummy_dec_parser = {
     "dummy_dec_parser",
     MPP_VIDEO_CodingUnused,
-    0,
+    sizeof(DummyDec),
     0,
     dummy_dec_init,
     dummy_dec_deinit,
diff --git a/mpp/codec/inc/dummy_dec_api.h b/mpp/codec/inc/dummy_dec_api.h
index 7da2c4d3..84a505a1 100644
--- a/mpp/codec/inc/dummy_dec_api.h
+++ b/mpp/codec/inc/dummy_dec_api.h
@@ -25,12 +25,12 @@ extern "C" {
 
 extern const MppDecParser dummy_dec_parser;
 
-MPP_RET dummy_dec_init   (void *decoder, MppParserInitCfg *cfg);
-MPP_RET dummy_dec_deinit (void *decoder);
-MPP_RET dummy_dec_reset  (void *decoder);
-MPP_RET dummy_dec_flush  (void *decoder);
-MPP_RET dummy_dec_control(void *decoder, RK_S32 cmd_type, void *param);
-MPP_RET dummy_dec_parse  (void *decoder, MppPacket pkt, HalDecTask *task);
+MPP_RET dummy_dec_init   (void *dec, MppParserInitCfg *cfg);
+MPP_RET dummy_dec_deinit (void *dec);
+MPP_RET dummy_dec_reset  (void *dec);
+MPP_RET dummy_dec_flush  (void *dec);
+MPP_RET dummy_dec_control(void *dec, RK_S32 cmd_type, void *param);
+MPP_RET dummy_dec_parse  (void *dec, MppPacket pkt, HalDecTask *task);
 
 #ifdef  __cplusplus
 }
diff --git a/mpp/codec/mpp_buf_slot.cpp b/mpp/codec/mpp_buf_slot.cpp
index 9ef82fdc..751c3fe0 100644
--- a/mpp/codec/mpp_buf_slot.cpp
+++ b/mpp/codec/mpp_buf_slot.cpp
@@ -70,17 +70,13 @@ MPP_RET mpp_buf_slot_init(MppBufSlots *slots)
         mpp_err_f("found NULL input\n");
         return MPP_ERR_NULL_PTR;
     }
-    MppBufSlotsImpl *impl = mpp_malloc(MppBufSlotsImpl, 1);
+    MppBufSlotsImpl *impl = mpp_calloc(MppBufSlotsImpl, 1);
     if (NULL == impl) {
         *slots = NULL;
         return MPP_NOK;
     }
 
     impl->lock = new Mutex();
-    impl->count = 0;
-    impl->decode_count = 0;
-    impl->display_count = 0;
-    impl->slots = NULL;
     *slots = impl;
     return MPP_OK;
 }
@@ -113,8 +109,6 @@ MPP_RET mpp_buf_slot_setup(MppBufSlots slots, RK_U32 count, RK_U32 size, RK_U32
         impl->slots = mpp_calloc(MppBufSlotEntry, count);
         impl->count = count;
         impl->size  = size;
-        impl->slots = (MppBufSlotEntry *)(impl + 1);
-        memset(impl->slots, 0, sizeof(MppBufSlotEntry) * count);
     } else {
         // need to check info change or not
         if (!changed) {
@@ -183,7 +177,7 @@ RK_U32  mpp_buf_slot_get_size(MppBufSlots slots)
 
 MPP_RET mpp_buf_slot_get_unused(MppBufSlots slots, RK_U32 *index)
 {
-    if (NULL == slots) {
+    if (NULL == slots || NULL == index) {
         mpp_err_f("found NULL input\n");
         return MPP_ERR_NULL_PTR;
     }