h264: eliminate default_ref_list

According to the spec, the reference list for a slice should be
constructed by first generating an initial (what we now call "default")
reference list and then optionally applying modifications to it.

Our code has an optimization where the initial reference list is
constructed for the first inter slice and then rebuilt for other slices
if needed. This, however, adds complexity to the code, requires an extra
2.5kB array in the codec context and there is no reason to think that it
has any positive effect on performance. Therefore, simplify the code by
generating the reference list from scratch for each slice.

1 files changed, 1 insertions, 17 deletions

diff --git a/libavcodec/h264_slice.c b/libavcodec/h264_slice.c
index 49fd89135d..4c825887a6 100644
--- a/libavcodec/h264_slice.c
+++ b/libavcodec/h264_slice.c
@@ -510,18 +510,13 @@ int ff_h264_update_thread_context(AVCodecContext *dst,
     h->dequant_coeff_pps = h1->dequant_coeff_pps;
 
     // POC timing
-    copy_fields(h, h1, poc_lsb, default_ref_list);
-
-    // reference lists
-    copy_fields(h, h1, short_ref, current_slice);
+    copy_fields(h, h1, poc_lsb, current_slice);
 
     copy_picture_range(h->short_ref, h1->short_ref, 32, h, h1);
     copy_picture_range(h->long_ref, h1->long_ref, 32, h, h1);
     copy_picture_range(h->delayed_pic, h1->delayed_pic,
                        MAX_DELAYED_PIC_COUNT + 2, h, h1);
 
-    h->last_slice_type = h1->last_slice_type;
-
     if (!h->cur_pic_ptr)
         return 0;
 
@@ -1032,7 +1027,6 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl)
     unsigned int pps_id;
     int ret;
     unsigned int slice_type, tmp, i, j;
-    int default_ref_list_done = 0;
     int last_pic_structure, last_pic_droppable;
     int needs_reinit = 0;
     int field_pic_flag, bottom_field_flag;
@@ -1073,10 +1067,6 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl)
         sl->slice_type_fixed = 0;
 
     slice_type = golomb_to_pict_type[slice_type];
-    if (slice_type == AV_PICTURE_TYPE_I ||
-        (h->current_slice != 0 && slice_type == h->last_slice_type)) {
-        default_ref_list_done = 1;
-    }
     sl->slice_type     = slice_type;
     sl->slice_type_nos = slice_type & 3;
 
@@ -1491,11 +1481,6 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl)
     ret = ff_set_ref_count(h, sl);
     if (ret < 0)
         return ret;
-    else if (ret == 1)
-        default_ref_list_done = 0;
-
-    if (!default_ref_list_done)
-        ff_h264_fill_default_ref_list(h, sl);
 
     if (sl->slice_type_nos != AV_PICTURE_TYPE_I) {
        ret = ff_h264_decode_ref_pic_list_reordering(h, sl);
@@ -1635,7 +1620,6 @@ int ff_h264_decode_slice_header(H264Context *h, H264SliceContext *sl)
                           h->pps.chroma_qp_index_offset[1]) +
                    6 * (h->sps.bit_depth_luma - 8);
 
-    h->last_slice_type = slice_type;
     sl->slice_num       = ++h->current_slice;
     if (sl->slice_num >= MAX_SLICES) {
         av_log(h->avctx, AV_LOG_ERROR,