lavc/vaapi_encode_h264: fix poc incorrect issue after meeting idr frame.

when meeting IDR frame, vaapi_encode_h264 poc number don't reset, now fix
this issue based on h264 spec. Some decoder don't care this case, but this
fix will enhance the encoder action. Before this fix, poc number is
negative in some case.
Reviewed-by: Jun Zhao <jun.zhao@intel.com>
Signed-off-by: Wang, Yi A <yi.a.wang@intel.com>
Signed-off-by: Mark Thompson <sw@jkqxz.net>

libavcodec/vaapi_encode_h264.c

@@ -146,6 +146,7 @@ typedef struct VAAPIEncodeH264Context {
     int fixed_qp_b;
 
     int next_frame_num;
+    int64_t last_idr_frame;
     int64_t idr_pic_count;
 
     int cpb_delay;
@@ -960,6 +961,7 @@ static int vaapi_encode_h264_init_picture_params(AVCodecContext *avctx,
         vpic->frame_num = 0;
         priv->next_frame_num = 1;
         priv->cpb_delay = 0;
+        priv->last_idr_frame = pic->display_order;
     } else {
         vpic->frame_num = priv->next_frame_num;
         if (pic->type != PICTURE_TYPE_B) {
@@ -976,8 +978,8 @@ static int vaapi_encode_h264_init_picture_params(AVCodecContext *avctx,
     vpic->CurrPic.picture_id          = pic->recon_surface;
     vpic->CurrPic.frame_idx           = vpic->frame_num;
     vpic->CurrPic.flags               = 0;
-    vpic->CurrPic.TopFieldOrderCnt    = pic->display_order;
-    vpic->CurrPic.BottomFieldOrderCnt = pic->display_order;
+    vpic->CurrPic.TopFieldOrderCnt    = pic->display_order - priv->last_idr_frame;
+    vpic->CurrPic.BottomFieldOrderCnt = pic->display_order - priv->last_idr_frame;
 
     for (i = 0; i < pic->nb_refs; i++) {
         VAAPIEncodePicture *ref = pic->refs[i];
@@ -985,8 +987,8 @@ static int vaapi_encode_h264_init_picture_params(AVCodecContext *avctx,
         vpic->ReferenceFrames[i].picture_id = ref->recon_surface;
         vpic->ReferenceFrames[i].frame_idx  = ref->encode_order;
         vpic->ReferenceFrames[i].flags = VA_PICTURE_H264_SHORT_TERM_REFERENCE;
-        vpic->ReferenceFrames[i].TopFieldOrderCnt    = ref->display_order;
-        vpic->ReferenceFrames[i].BottomFieldOrderCnt = ref->display_order;
+        vpic->ReferenceFrames[i].TopFieldOrderCnt    = ref->display_order - priv->last_idr_frame;
+        vpic->ReferenceFrames[i].BottomFieldOrderCnt = ref->display_order - priv->last_idr_frame;
     }
     for (; i < FF_ARRAY_ELEMS(vpic->ReferenceFrames); i++) {
         vpic->ReferenceFrames[i].picture_id = VA_INVALID_ID;
@@ -1057,7 +1059,7 @@ static int vaapi_encode_h264_init_slice_params(AVCodecContext *avctx,
     vslice->pic_parameter_set_id = vpic->pic_parameter_set_id;
     vslice->idr_pic_id = priv->idr_pic_count++;
 
-    vslice->pic_order_cnt_lsb = pic->display_order &
+    vslice->pic_order_cnt_lsb = (pic->display_order - priv->last_idr_frame) &
         ((1 << (4 + vseq->seq_fields.bits.log2_max_pic_order_cnt_lsb_minus4)) - 1);
 
     for (i = 0; i < FF_ARRAY_ELEMS(vslice->RefPicList0); i++) {