diff --git a/mpp/base/mpp_packet.cpp b/mpp/base/mpp_packet.cpp
index 8ba1d168..3b79b85b 100644
--- a/mpp/base/mpp_packet.cpp
+++ b/mpp/base/mpp_packet.cpp
@@ -117,29 +117,32 @@ MPP_RET mpp_packet_copy_init(MppPacket *packet, const MppPacket src)
         return MPP_OK;
     }
 
-    size_t size = mpp_packet_get_size(src);
+    /*
+     * NOTE: only copy valid data
+     */
+    size_t length = mpp_packet_get_length(src);
     /*
      * due to parser may be read 32 bit interface so we must alloc more size then real size
      * to avoid read carsh
      */
-    void *data = mpp_malloc_size(void, size + 256);
-    if (NULL == data) {
-        mpp_err_f("malloc failed, size %d\n", size);
+    void *pos = mpp_malloc_size(void, length + 256);
+    if (NULL == pos) {
+        mpp_err_f("malloc failed, size %d\n", length);
         mpp_packet_deinit(&pkt);
         return MPP_ERR_MALLOC;
     }
 
     MppPacketImpl *p = (MppPacketImpl *)pkt;
     memcpy(p, src_impl, sizeof(*src_impl));
-    p->data = p->pos = data;
-    p->size = p->length = size;
+    p->data = p->pos = pos;
+    p->size = p->length = length;
     p->flag |= MPP_PACKET_FLAG_INTERNAL;
-    if (size) {
-        memcpy(data, src_impl->data, size);
+    if (length) {
+        memcpy(pos, src_impl->pos, length);
         /*
          * clean more alloc byte to zero
         */
-        memset((RK_U8*)data + size, 0, 256);
+        memset((RK_U8*)pos + length, 0, 256);
     }
     *packet = pkt;
     return MPP_OK;
@@ -173,8 +176,8 @@ void mpp_packet_set_pos(MppPacket packet, void *pos)
         return ;
 
     MppPacketImpl *p = (MppPacketImpl *)packet;
-    p->pos    = pos;
-    p->length = p->size - ((char *)pos - (char *)p->data);
+    p->length -= (RK_U8 *)pos - (RK_U8 *)p->pos;
+    p->pos = pos;
     mpp_assert(p->data <= p->pos);
     mpp_assert(p->size >= p->length);
 }
diff --git a/test/mpi_dec_test.c b/test/mpi_dec_test.c
index 945e324c..961edc9c 100644
--- a/test/mpi_dec_test.c
+++ b/test/mpi_dec_test.c
@@ -31,7 +31,7 @@
 #include "utils.h"
 
 #define MPI_DEC_LOOP_COUNT          4
-#define MPI_DEC_STREAM_SIZE         (SZ_2K)
+#define MPI_DEC_STREAM_SIZE         (SZ_4K)
 #define MAX_FILE_NAME_LENGTH        256
 
 typedef struct {
@@ -100,9 +100,12 @@ static int decode_simple(MpiDecLoopData *data)
 
     // write data to packet
     mpp_packet_write(packet, 0, buf, read_size);
-    // reset pos
+    // reset pos and set valid length
     mpp_packet_set_pos(packet, buf);
     mpp_packet_set_length(packet, read_size);
+    // setup eos flag
+    if (pkt_eos)
+        mpp_packet_set_eos(packet);
 
     do {
         // send the packet first if packet is not done
@@ -139,12 +142,18 @@ static int decode_simple(MpiDecLoopData *data)
             }
 
             // if last packet is send but last frame is not found continue
-            if (pkt_eos && pkt_done && !frm_eos)
+            if (pkt_eos && pkt_done && !frm_eos) {
+                msleep(10);
                 continue;
+            }
+
+            if (frm_eos) {
+                mpp_log("found last frame\n");
+                break;
+            }
 
             if (get_frm)
                 continue;
-
             break;
         } while (1);