avcodec/cbs_av1: fix parsing delta_frame_id_minus1

delta_frame_id_minus1 is not a single value in the bitstream, and can
store values up to 17 bits wide.

Fixes parsing files with frame ids.

Reviewed-by: Mark Thompson <sw@jkqxz.net>
Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/cbs_av1.h

@@ -170,7 +170,7 @@ typedef struct AV1RawFrameHeader {
     uint8_t last_frame_idx;
     uint8_t golden_frame_idx;
     int8_t  ref_frame_idx[AV1_REFS_PER_FRAME];
-    uint8_t delta_frame_id_minus1;
+    uint32_t delta_frame_id_minus1[AV1_REFS_PER_FRAME];
 
     uint8_t allow_high_precision_mv;
     uint8_t is_filter_switchable;

libavcodec/cbs_av1_syntax_template.c

@@ -1323,8 +1323,8 @@ static int FUNC(uncompressed_header)(CodedBitstreamContext *ctx, RWContext *rw,
             if (!current->frame_refs_short_signaling)
                 fbs(3, ref_frame_idx[i], 1, i);
             if (seq->frame_id_numbers_present_flag) {
-                fb(seq->delta_frame_id_length_minus_2 + 2,
+                fbs(seq->delta_frame_id_length_minus_2 + 2,
-                   delta_frame_id_minus1);
+                    delta_frame_id_minus1[i], 1, i);
             }
         }