From fb30c9107aa93deebcc61fc0eb382a0b4bf8bf54 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Wed, 27 May 2020 11:01:12 +0200
Subject: [PATCH] hevc_parser: drop the use of SliceHeader

It is only used to store a few local variables within one function,
which is better accomplished by just declaring them on stack explicitly.
---
 libavcodec/hevc_parser.c | 57 +++++++++++++++++++++-------------------
 1 file changed, 30 insertions(+), 27 deletions(-)

diff --git a/libavcodec/hevc_parser.c b/libavcodec/hevc_parser.c
index 84f19b485c..5af4b788d5 100644
--- a/libavcodec/hevc_parser.c
+++ b/libavcodec/hevc_parser.c
@@ -42,7 +42,6 @@ typedef struct HEVCParserContext {
     H2645Packet pkt;
     HEVCParamSets ps;
     HEVCSEI sei;
-    SliceHeader sh;
 
     int is_avc;
     int nal_length_size;
@@ -58,26 +57,28 @@ static int hevc_parse_slice_header(AVCodecParserContext *s, H2645NAL *nal,
     HEVCParserContext *ctx = s->priv_data;
     HEVCParamSets *ps = &ctx->ps;
     HEVCSEI *sei = &ctx->sei;
-    SliceHeader *sh = &ctx->sh;
     GetBitContext *gb = &nal->gb;
     const HEVCWindow *ow;
     int i, num = 0, den = 0;
 
-    sh->first_slice_in_pic_flag = get_bits1(gb);
+    unsigned int pps_id, first_slice_in_pic_flag, dependent_slice_segment_flag;
+    enum HEVCSliceType slice_type;
+
+    first_slice_in_pic_flag = get_bits1(gb);
     s->picture_structure = sei->picture_timing.picture_struct;
     s->field_order = sei->picture_timing.picture_struct;
 
     if (IS_IRAP_NAL(nal)) {
         s->key_frame = 1;
-        sh->no_output_of_prior_pics_flag = get_bits1(gb);
+        skip_bits1(gb); // no_output_of_prior_pics_flag
     }
 
-    sh->pps_id = get_ue_golomb(gb);
-    if (sh->pps_id >= HEVC_MAX_PPS_COUNT || !ps->pps_list[sh->pps_id]) {
-        av_log(avctx, AV_LOG_ERROR, "PPS id out of range: %d\n", sh->pps_id);
+    pps_id = get_ue_golomb(gb);
+    if (pps_id >= HEVC_MAX_PPS_COUNT || !ps->pps_list[pps_id]) {
+        av_log(avctx, AV_LOG_ERROR, "PPS id out of range: %d\n", pps_id);
         return AVERROR_INVALIDDATA;
     }
-    ps->pps = (HEVCPPS*)ps->pps_list[sh->pps_id]->data;
+    ps->pps = (HEVCPPS*)ps->pps_list[pps_id]->data;
 
     if (ps->pps->sps_id >= HEVC_MAX_SPS_COUNT || !ps->sps_list[ps->pps->sps_id]) {
         av_log(avctx, AV_LOG_ERROR, "SPS id out of range: %d\n", ps->pps->sps_id);
@@ -109,51 +110,53 @@ static int hevc_parse_slice_header(AVCodecParserContext *s, H2645NAL *nal,
         av_reduce(&avctx->framerate.den, &avctx->framerate.num,
                   num, den, 1 << 30);
 
-    if (!sh->first_slice_in_pic_flag) {
+    if (!first_slice_in_pic_flag) {
+        unsigned int slice_segment_addr;
         int slice_address_length;
 
         if (ps->pps->dependent_slice_segments_enabled_flag)
-            sh->dependent_slice_segment_flag = get_bits1(gb);
+            dependent_slice_segment_flag = get_bits1(gb);
         else
-            sh->dependent_slice_segment_flag = 0;
+            dependent_slice_segment_flag = 0;
 
         slice_address_length = av_ceil_log2_c(ps->sps->ctb_width *
                                               ps->sps->ctb_height);
-        sh->slice_segment_addr = get_bitsz(gb, slice_address_length);
-        if (sh->slice_segment_addr >= ps->sps->ctb_width * ps->sps->ctb_height) {
+        slice_segment_addr = get_bitsz(gb, slice_address_length);
+        if (slice_segment_addr >= ps->sps->ctb_width * ps->sps->ctb_height) {
             av_log(avctx, AV_LOG_ERROR, "Invalid slice segment address: %u.\n",
-                   sh->slice_segment_addr);
+                   slice_segment_addr);
             return AVERROR_INVALIDDATA;
         }
     } else
-        sh->dependent_slice_segment_flag = 0;
+        dependent_slice_segment_flag = 0;
 
-    if (sh->dependent_slice_segment_flag)
+    if (dependent_slice_segment_flag)
         return 0; /* break; */
 
     for (i = 0; i < ps->pps->num_extra_slice_header_bits; i++)
         skip_bits(gb, 1); // slice_reserved_undetermined_flag[]
 
-    sh->slice_type = get_ue_golomb(gb);
-    if (!(sh->slice_type == HEVC_SLICE_I || sh->slice_type == HEVC_SLICE_P ||
-          sh->slice_type == HEVC_SLICE_B)) {
+    slice_type = get_ue_golomb(gb);
+    if (!(slice_type == HEVC_SLICE_I || slice_type == HEVC_SLICE_P ||
+          slice_type == HEVC_SLICE_B)) {
         av_log(avctx, AV_LOG_ERROR, "Unknown slice type: %d.\n",
-               sh->slice_type);
+               slice_type);
         return AVERROR_INVALIDDATA;
     }
-    s->pict_type = sh->slice_type == HEVC_SLICE_B ? AV_PICTURE_TYPE_B :
-                   sh->slice_type == HEVC_SLICE_P ? AV_PICTURE_TYPE_P :
-                                               AV_PICTURE_TYPE_I;
+    s->pict_type = slice_type == HEVC_SLICE_B ? AV_PICTURE_TYPE_B :
+                   slice_type == HEVC_SLICE_P ? AV_PICTURE_TYPE_P :
+                                                AV_PICTURE_TYPE_I;
 
     if (ps->pps->output_flag_present_flag)
-        sh->pic_output_flag = get_bits1(gb);
+        skip_bits1(gb); // pic_output_flag
 
     if (ps->sps->separate_colour_plane_flag)
-        sh->colour_plane_id = get_bits(gb, 2);
+        skip_bits(gb, 2);   // colour_plane_id
 
     if (!IS_IDR_NAL(nal)) {
-        sh->pic_order_cnt_lsb = get_bits(gb, ps->sps->log2_max_poc_lsb);
-        s->output_picture_number = ctx->poc = ff_hevc_compute_poc(ps->sps, ctx->pocTid0, sh->pic_order_cnt_lsb, nal->type);
+        int pic_order_cnt_lsb = get_bits(gb, ps->sps->log2_max_poc_lsb);
+        s->output_picture_number = ctx->poc =
+            ff_hevc_compute_poc(ps->sps, ctx->pocTid0, pic_order_cnt_lsb, nal->type);
     } else
         s->output_picture_number = ctx->poc = 0;