[FFmpeg-devel,V2] avcodec-qsvdec-flush-the-buffered-data-before-reinit

diff --git a/libavcodec/qsvdec.c b/libavcodec/qsvdec.c
index 22e7a46a85..6753e596a1 100644
--- a/libavcodec/qsvdec.c
+++ b/libavcodec/qsvdec.c
@@ -372,6 +372,8 @@  static int qsv_decode(AVCodecContext *avctx, QSVContext *q,
         ++q->zero_consume_run;
         if (q->zero_consume_run > 1)
             ff_qsv_print_warning(avctx, ret, "A decode call did not consume any data");
+    } else if (!*sync && bs.DataOffset) {
+        ++q->buffered_count;
     } else {
         q->zero_consume_run = 0;
     }
@@ -526,6 +528,16 @@  int ff_qsv_process_data(AVCodecContext *avctx, QSVContext *q,
                                            AV_PIX_FMT_NONE,
                                            AV_PIX_FMT_NONE };
         enum AVPixelFormat qsv_format;
+        AVPacket zero_pkt = {0};
+
+        if (q->buffered_count) {
+            q->reinit_flag = 1;
+            /* decode zero-size pkt to flush the buffered pkt before reinit */
+            q->buffered_count--;
+            return qsv_decode(avctx, q, frame, got_frame, &zero_pkt);
+        }
+
+        q->reinit_flag = 0;
 
         qsv_format = ff_qsv_map_pixfmt(q->parser->format, &q->fourcc);
         if (qsv_format < 0) {
diff --git a/libavcodec/qsvdec.h b/libavcodec/qsvdec.h
index 5b7b03a48b..111536caba 100644
--- a/libavcodec/qsvdec.h
+++ b/libavcodec/qsvdec.h
@@ -53,6 +53,8 @@  typedef struct QSVContext {
 
     AVFifoBuffer *async_fifo;
     int zero_consume_run;
+    int buffered_count;
+    int reinit_flag;
 
     // the internal parser and codec context for parsing the data
     AVCodecParserContext *parser;
diff --git a/libavcodec/qsvdec_h2645.c b/libavcodec/qsvdec_h2645.c
index d9d2318d1a..b8a78aa81b 100644
--- a/libavcodec/qsvdec_h2645.c
+++ b/libavcodec/qsvdec_h2645.c
@@ -146,10 +146,11 @@  static int qsv_decode_frame(AVCodecContext *avctx, void *data,
             /* no more data */
             if (av_fifo_size(s->packet_fifo) < sizeof(AVPacket))
                 return avpkt->size ? avpkt->size : ff_qsv_process_data(avctx, &s->qsv, frame, got_frame, avpkt);
-
-            av_packet_unref(&s->buffer_pkt);
-
-            av_fifo_generic_read(s->packet_fifo, &s->buffer_pkt, sizeof(s->buffer_pkt), NULL);
+            /* in progress of reinit, no read from fifo and keep the buffer_pkt */
+            if (!s->qsv.reinit_flag) {
+                av_packet_unref(&s->buffer_pkt);
+                av_fifo_generic_read(s->packet_fifo, &s->buffer_pkt, sizeof(s->buffer_pkt), NULL);
+            }
         }
 
         ret = ff_qsv_process_data(avctx, &s->qsv, frame, got_frame, &s->buffer_pkt);
@@ -159,6 +160,8 @@  static int qsv_decode_frame(AVCodecContext *avctx, void *data,
             av_packet_unref(&s->buffer_pkt);
             return ret;
         }
+        if (s->qsv.reinit_flag)
+            continue;
 
         s->buffer_pkt.size -= ret;
         s->buffer_pkt.data += ret;
diff --git a/libavcodec/qsvdec_other.c b/libavcodec/qsvdec_other.c
index 993c7a8e80..b449bb21b7 100644
--- a/libavcodec/qsvdec_other.c
+++ b/libavcodec/qsvdec_other.c
@@ -132,9 +132,11 @@  static int qsv_decode_frame(AVCodecContext *avctx, void *data,
             /* no more data */
             if (av_fifo_size(s->packet_fifo) < sizeof(AVPacket))
                 return avpkt->size ? avpkt->size : ff_qsv_process_data(avctx, &s->qsv, frame, got_frame, avpkt);
-
-            av_packet_unref(&s->input_ref);
-            av_fifo_generic_read(s->packet_fifo, &s->input_ref, sizeof(s->input_ref), NULL);
+            /* in progress of reinit, no read from fifo and keep the buffer_pkt */ 
+            if (!s->qsv.reinit_flag) {
+                av_packet_unref(&s->input_ref);
+                av_fifo_generic_read(s->packet_fifo, &s->input_ref, sizeof(s->input_ref), NULL);
+            }
         }
 
         ret = ff_qsv_process_data(avctx, &s->qsv, frame, got_frame, &s->input_ref);
@@ -145,6 +147,8 @@  static int qsv_decode_frame(AVCodecContext *avctx, void *data,
 
             return ret;
         }
+        if (s->qsv.reinit_flag)
+            continue;
 
         s->input_ref.size -= ret;
         s->input_ref.data += ret;