Reset current_video_frame in key frame

Reset the frame index tracking to 0 when key frame is inserted in
the frame sequence.

Change-Id: Ib80313004fc000e7127a9797af5afe9029c0cb45

av1/decoder/decodeframe.c

@@ -3039,6 +3039,7 @@ static size_t read_uncompressed_header(AV1Decoder *pbi,
   }
 #endif  // CONFIG_REFERENCE_BUFFER
   if (cm->frame_type == KEY_FRAME) {
+    cm->current_video_frame = 0;
 #if !CONFIG_OBU
     read_bitdepth_colorspace_sampling(cm, rb, pbi->allow_lowbitdepth);
 #endif

av1/encoder/encoder.c

@@ -5283,6 +5283,9 @@ static void encode_frame_to_data_rate(AV1_COMP *cpi, size_t *size,
       !cpi->oxcf.disable_tempmv && !cm->cur_frame->intra_only;
 #endif
 
+  // Reset the frame packet stamp index.
+  if (cm->frame_type == KEY_FRAME) cm->current_video_frame = 0;
+
   // NOTE:
   // (1) Move the setup of the ref_frame_flags upfront as it would be
   //     determined by the current frame properties;