cbs_h264: Move slice_group_id array out of PPS structure

It's very large, and is only used in some FMO streams.

libavcodec/cbs_h264.h

@@ -195,7 +195,9 @@ typedef struct H264RawPPS {
     uint8_t slice_group_change_direction_flag;
     uint16_t slice_group_change_rate_minus1;
     uint16_t pic_size_in_map_units_minus1;
-    uint8_t slice_group_id[H264_MAX_MB_PIC_SIZE];
+
+    uint8_t *slice_group_id;
+    AVBufferRef *slice_group_id_ref;
 
     uint8_t num_ref_idx_l0_default_active_minus1;
     uint8_t num_ref_idx_l1_default_active_minus1;

libavcodec/cbs_h2645.c

@@ -394,6 +394,13 @@ static int cbs_h2645_read_more_rbsp_data(BitstreamContext *bc)
 #undef allocate
 
 
+static void cbs_h264_free_pps(void *unit, uint8_t *content)
+{
+    H264RawPPS *pps = (H264RawPPS*)content;
+    av_buffer_unref(&pps->slice_group_id_ref);
+    av_freep(&content);
+}
+
 static void cbs_h264_free_sei_payload(H264RawSEIPayload *payload)
 {
     switch (payload->payload_type) {
@@ -725,7 +732,8 @@ static int cbs_h264_read_nal_unit(CodedBitstreamContext *ctx,
         {
             H264RawPPS *pps;
 
-            err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*pps), NULL);
+            err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*pps),
+                                            &cbs_h264_free_pps);
             if (err < 0)
                 return err;
             pps = unit->content;

libavcodec/cbs_h264_syntax_template.c

@@ -404,6 +404,9 @@ static int FUNC(pps)(CodedBitstreamContext *ctx, RWContext *rw,
             ue(slice_group_change_rate_minus1, 0, pic_size - 1);
         } else if (current->slice_group_map_type == 6) {
             ue(pic_size_in_map_units_minus1, pic_size - 1, pic_size - 1);
+
+            allocate(current->slice_group_id,
+                     current->pic_size_in_map_units_minus1 + 1);
             for (i = 0; i <= current->pic_size_in_map_units_minus1; i++)
                 u(av_log2(2 * current->num_slice_groups_minus1 + 1),
                   slice_group_id[i], 0, current->num_slice_groups_minus1);