[FFmpeg-devel,v3] avcodec/decode: port last_pkt_props to AVFifoBuffer

diff --git a/libavcodec/decode.c b/libavcodec/decode.c
index 8086362eb2..9d7cc107ae 100644
--- a/libavcodec/decode.c
+++ b/libavcodec/decode.c
@@ -145,24 +145,44 @@  fail2:
 
 #define IS_EMPTY(pkt) (!(pkt)->data)
 
+static int copy_packet_props(AVPacket *dst, AVPacket *src)
+{
+    int ret = av_packet_copy_props(dst, src);
+    if (ret < 0)
+        return ret;
+
+    dst->size = src->size; // HACK: Needed for ff_decode_frame_props().
+    dst->data = (void*)1;  // HACK: Needed for IS_EMPTY().
+
+    return 0;
+}
+
 static int extract_packet_props(AVCodecInternal *avci, AVPacket *pkt)
 {
+    AVPacket tmp = { 0 };
     int ret = 0;
 
-    ret = avpriv_packet_list_put(&avci->pkt_props, &avci->pkt_props_tail, pkt,
-                                 av_packet_copy_props, 0);
+    if (IS_EMPTY(avci->last_pkt_props)) {
+        if (av_fifo_size(avci->pkt_props) >= sizeof(*pkt)) {
+            av_fifo_generic_read(avci->pkt_props, avci->last_pkt_props,
+                                 sizeof(*avci->last_pkt_props), NULL);
+        } else
+            return copy_packet_props(avci->last_pkt_props, pkt);
+    }
+
+    if (av_fifo_space(avci->pkt_props) < sizeof(*pkt)) {
+        ret = av_fifo_grow(avci->pkt_props, sizeof(*pkt));
+        if (ret < 0)
+            return ret;
+    }
+
+    ret = copy_packet_props(&tmp, pkt);
     if (ret < 0)
         return ret;
-    avci->pkt_props_tail->pkt.size = pkt->size; // HACK: Needed for ff_decode_frame_props().
-    avci->pkt_props_tail->pkt.data = (void*)1;  // HACK: Needed for IS_EMPTY().
 
-    if (IS_EMPTY(avci->last_pkt_props)) {
-        ret = avpriv_packet_list_get(&avci->pkt_props,
-                                     &avci->pkt_props_tail,
-                                     avci->last_pkt_props);
-        av_assert0(ret != AVERROR(EAGAIN));
-    }
-    return ret;
+    av_fifo_generic_write(avci->pkt_props, &tmp, sizeof(tmp), NULL);
+
+    return 0;
 }
 
 int ff_decode_bsfs_init(AVCodecContext *avctx)
@@ -1726,10 +1746,9 @@  int ff_decode_frame_props(AVCodecContext *avctx, AVFrame *frame)
         { AV_PKT_DATA_S12M_TIMECODE,              AV_FRAME_DATA_S12M_TIMECODE },
     };
 
-    if (IS_EMPTY(pkt))
-        avpriv_packet_list_get(&avctx->internal->pkt_props,
-                               &avctx->internal->pkt_props_tail,
-                               pkt);
+    if (IS_EMPTY(pkt) && av_fifo_size(avctx->internal->pkt_props) >= sizeof(*pkt))
+        av_fifo_generic_read(avctx->internal->pkt_props,
+                             pkt, sizeof(*pkt), NULL);
 
     if (pkt) {
         frame->pts = pkt->pts;
diff --git a/libavcodec/internal.h b/libavcodec/internal.h
index 65760368d6..400ea508ef 100644
--- a/libavcodec/internal.h
+++ b/libavcodec/internal.h
@@ -28,6 +28,7 @@ 
 
 #include "libavutil/buffer.h"
 #include "libavutil/channel_layout.h"
+#include "libavutil/fifo.h"
 #include "libavutil/mathematics.h"
 #include "libavutil/pixfmt.h"
 #include "avcodec.h"
@@ -147,8 +148,7 @@  typedef struct AVCodecInternal {
      * for decoding.
      */
     AVPacket *last_pkt_props;
-    AVPacketList *pkt_props;
-    AVPacketList *pkt_props_tail;
+    AVFifoBuffer *pkt_props;
 
     /**
      * temporary buffer used for encoders to store their bitstream
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index db6cd0cde8..32d0288faa 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -594,9 +594,10 @@  int attribute_align_arg avcodec_open2(AVCodecContext *avctx, const AVCodec *code
     avci->es.in_frame = av_frame_alloc();
     avci->ds.in_pkt = av_packet_alloc();
     avci->last_pkt_props = av_packet_alloc();
+    avci->pkt_props = av_fifo_alloc(sizeof(*avci->last_pkt_props));
     if (!avci->buffer_frame || !avci->buffer_pkt          ||
         !avci->es.in_frame  || !avci->ds.in_pkt           ||
-        !avci->last_pkt_props) {
+        !avci->last_pkt_props || !avci->pkt_props) {
         ret = AVERROR(ENOMEM);
         goto free_and_end;
     }
@@ -1077,7 +1078,7 @@  FF_ENABLE_DEPRECATION_WARNINGS
 #endif
     av_frame_free(&avci->buffer_frame);
     av_packet_free(&avci->buffer_pkt);
-    av_packet_free(&avci->last_pkt_props);
+    av_fifo_freep(&avci->pkt_props);
 
     av_packet_free(&avci->ds.in_pkt);
     av_frame_free(&avci->es.in_frame);
@@ -1120,8 +1121,13 @@  void avcodec_flush_buffers(AVCodecContext *avctx)
     av_packet_unref(avci->buffer_pkt);
 
     av_packet_unref(avci->last_pkt_props);
-    avpriv_packet_list_free(&avci->pkt_props,
-                            &avci->pkt_props_tail);
+    while (av_fifo_size(avci->pkt_props) >= sizeof(*avci->last_pkt_props)) {
+        av_fifo_generic_read(avci->pkt_props,
+                             avci->last_pkt_props, sizeof(*avci->last_pkt_props),
+                             NULL);
+        av_packet_unref(avci->last_pkt_props);
+    }
+    av_fifo_reset(avci->pkt_props);
 
     av_frame_unref(avci->es.in_frame);
     av_packet_unref(avci->ds.in_pkt);
@@ -1189,9 +1195,17 @@  av_cold int avcodec_close(AVCodecContext *avctx)
 #endif
         av_frame_free(&avctx->internal->buffer_frame);
         av_packet_free(&avctx->internal->buffer_pkt);
+        av_packet_unref(avctx->internal->last_pkt_props);
+        while (av_fifo_size(avctx->internal->pkt_props) >=
+               sizeof(*avctx->internal->last_pkt_props)) {
+            av_fifo_generic_read(avctx->internal->pkt_props,
+                                 avctx->internal->last_pkt_props,
+                                 sizeof(*avctx->internal->last_pkt_props),
+                                 NULL);
+            av_packet_unref(avctx->internal->last_pkt_props);
+        }
         av_packet_free(&avctx->internal->last_pkt_props);
-        avpriv_packet_list_free(&avctx->internal->pkt_props,
-                                &avctx->internal->pkt_props_tail);
+        av_fifo_freep(&avctx->internal->pkt_props);
 
         av_packet_free(&avctx->internal->ds.in_pkt);
         av_frame_free(&avctx->internal->es.in_frame);