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h264parse: use of ceil_log2 instead of bit_storage

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According to the specification:
The length of the slice_group_id[ i ] syntax element is Ceil( Log2(
num_slice_groups_minus1 + 1 ) ) bits

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/7429>
This commit is contained in:
Stéphane Cerveau 2024-10-09 13:46:17 -04:00 committed by GStreamer Marge Bot
parent a6f82ba590
commit 8f9ed667cd
1 changed files with 4 additions and 2 deletions
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6
subprojects/gst-plugins-bad/gst-libs/gst/codecparsers/gsth264parser.c
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@ -2320,7 +2320,8 @@ gst_h264_parse_pps (GstH264NalParser * nalparser, GstH264NalUnit * nalu,
gint i;
READ_UE (&nr, pps->pic_size_in_map_units_minus1);
bits = g_bit_storage (pps->num_slice_groups_minus1);
/* 7.4.2.2 7-23 slice_group_id */
bits = gst_util_ceil_log2 (pps->num_slice_groups_minus1 + 1);
pps->slice_group_id =
g_new (guint8, pps->pic_size_in_map_units_minus1 + 1);
@ -2600,11 +2601,12 @@ gst_h264_parser_parse_slice_hdr (GstH264NalParser * nalparser,
if (pps->num_slice_groups_minus1 > 0 &&
pps->slice_group_map_type >= 3 && pps->slice_group_map_type <= 5) {
/* Ceil(Log2(PicSizeInMapUnits / SliceGroupChangeRate + 1)) [7-33] */
guint32 PicWidthInMbs = sps->pic_width_in_mbs_minus1 + 1;
guint32 PicHeightInMapUnits = sps->pic_height_in_map_units_minus1 + 1;
guint32 PicSizeInMapUnits = PicWidthInMbs * PicHeightInMapUnits;
guint32 SliceGroupChangeRate = pps->slice_group_change_rate_minus1 + 1;
/* Ceil(Log2(PicSizeInMapUnits / SliceGroupChangeRate + 1)) [7-35] */
const guint n =
gst_util_ceil_log2 (PicSizeInMapUnits / SliceGroupChangeRate + 1);
READ_UINT16 (&nr, slice->slice_group_change_cycle, n);