[FFmpeg-devel] [PATCH v2] lavc/vvc: Use a bitfield to store MIP information
Frank Plowman
post at frankplowman.com
Tue Dec 3 22:47:25 EET 2024
Reduces memory consumption by ~4MB for 1080p video with a maximum delay
of 16 frames by packing various information related to MIP:
* intra_mip_flag, 1 bit
* intra_mip_transposed_flag, 1 bit
* intra_mip_mode, 4 bits
Into a single byte.
Co-authored-by: Nuo Mi <nuomi2021 at gmail.com>
Signed-off-by: Frank Plowman <post at frankplowman.com>
---
Changes since v1 (posted as attachment in other thread).
* Renamed (de)?structure_mip_info to (un)?pack_mip_info
* Remove coerce_to_bool argument added to get_inc. Instead, define a
variant of get_inc, get_mip_inc, particular to the MIP flag which
performs the necessary transformations.
I did also try implementing this patch as I mentioned I might on the
other thread: by adding a function pointer argument to get_inc and
get_left_top which can be used to transform values read from tables
before they are used. I realised while doing so, however, that there is
really no need for such complexity for get_left_top as it returns left
and top separately, hence the caller can simply transform them itself.
Then, get_inc is very simple and only called in two places, and so it is
not fitting to employ such heavy-duty abstractions only for that
function.
---
libavcodec/vvc/cabac.c | 10 +++++++++-
libavcodec/vvc/ctu.c | 12 +++++++++---
libavcodec/vvc/dec.c | 2 --
libavcodec/vvc/dec.h | 4 +---
libavcodec/vvc/dsp.c | 9 +++++++++
libavcodec/vvc/intra_template.c | 5 +++--
6 files changed, 31 insertions(+), 11 deletions(-)
diff --git a/libavcodec/vvc/cabac.c b/libavcodec/vvc/cabac.c
index 0d45eec751..5510144893 100644
--- a/libavcodec/vvc/cabac.c
+++ b/libavcodec/vvc/cabac.c
@@ -1257,11 +1257,19 @@ int ff_vvc_pred_mode_ibc_flag(VVCLocalContext *lc, const int is_chroma)
return GET_CABAC(PRED_MODE_IBC_FLAG + inc);
}
+static av_always_inline
+uint8_t get_mip_inc(VVCLocalContext *lc, const uint8_t *ctx)
+{
+ uint8_t left = 0, top = 0;
+ get_left_top(lc, &left, &top, lc->cu->x0, lc->cu->y0, ctx, ctx);
+ return (left & 1) + (top & 1);
+}
+
int ff_vvc_intra_mip_flag(VVCLocalContext *lc, const uint8_t *intra_mip_flag)
{
const int w = lc->cu->cb_width;
const int h = lc->cu->cb_height;
- const int inc = (w > h * 2 || h > w * 2) ? 3 : get_inc(lc, intra_mip_flag);
+ const int inc = (w > h * 2 || h > w * 2) ? 3 : get_mip_inc(lc, intra_mip_flag);
return GET_CABAC(INTRA_MIP_FLAG + inc);
}
diff --git a/libavcodec/vvc/ctu.c b/libavcodec/vvc/ctu.c
index 505099bc76..382fa582f4 100644
--- a/libavcodec/vvc/ctu.c
+++ b/libavcodec/vvc/ctu.c
@@ -946,6 +946,12 @@ static void derive_chroma_intra_pred_mode(VVCLocalContext *lc,
}
}
+static av_always_inline uint8_t pack_mip_info(int intra_mip_flag,
+ int intra_mip_transposed_flag, int intra_mip_mode)
+{
+ return (intra_mip_mode << 2) | (intra_mip_transposed_flag << 1) | intra_mip_flag;
+}
+
static void intra_luma_pred_modes(VVCLocalContext *lc)
{
VVCFrameContext *fc = lc->fc;
@@ -974,9 +980,9 @@ static void intra_luma_pred_modes(VVCLocalContext *lc)
int x = y_cb * pps->min_cb_width + x_cb;
for (int y = 0; y < (cb_height>>log2_min_cb_size); y++) {
int width = cb_width>>log2_min_cb_size;
- memset(&fc->tab.imf[x], cu->intra_mip_flag, width);
- memset(&fc->tab.imtf[x], intra_mip_transposed_flag, width);
- memset(&fc->tab.imm[x], intra_mip_mode, width);
+ const uint8_t mip_info = pack_mip_info(cu->intra_mip_flag,
+ intra_mip_transposed_flag, intra_mip_mode);
+ memset(&fc->tab.imf[x], mip_info, width);
x += pps->min_cb_width;
}
cu->intra_pred_mode_y = intra_mip_mode;
diff --git a/libavcodec/vvc/dec.c b/libavcodec/vvc/dec.c
index 50be9f9922..fef7339294 100644
--- a/libavcodec/vvc/dec.c
+++ b/libavcodec/vvc/dec.c
@@ -128,7 +128,6 @@ static void min_cb_tl_init(TabList *l, VVCFrameContext *fc)
tl_init(l, 1, changed);
TL_ADD(imf, pic_size_in_min_cb);
- TL_ADD(imm, pic_size_in_min_cb);
for (int i = LUMA; i <= CHROMA; i++)
TL_ADD(cb_width[i], pic_size_in_min_cb); //is_a0_available requires this
@@ -143,7 +142,6 @@ static void min_cb_nz_tl_init(TabList *l, VVCFrameContext *fc)
tl_init(l, 0, changed);
TL_ADD(skip, pic_size_in_min_cb);
- TL_ADD(imtf, pic_size_in_min_cb);
TL_ADD(ipm, pic_size_in_min_cb);
for (int i = LUMA; i <= CHROMA; i++) {
diff --git a/libavcodec/vvc/dec.h b/libavcodec/vvc/dec.h
index f7cd5b678c..0f8f1f721d 100644
--- a/libavcodec/vvc/dec.h
+++ b/libavcodec/vvc/dec.h
@@ -161,9 +161,7 @@ typedef struct VVCFrameContext {
uint8_t *skip; ///< CuSkipFlag[][]
uint8_t *ispmf; ///< intra_sub_partitions_mode_flag
uint8_t *msm[2]; ///< MttSplitMode[][][] in 32 pixels
- uint8_t *imf; ///< IntraMipFlag[][]
- uint8_t *imtf; ///< intra_mip_transposed_flag[][]
- uint8_t *imm; ///< intra_mip_mode[][]
+ uint8_t *imf; ///< IntraMipFlag[][], intra_mip_transposed_flag[][], intra_mip_mode[][]
uint8_t *ipm; ///< IntraPredModeY[][]
uint8_t *cpm[2]; ///< CuPredMode[][][]
uint8_t *msf; ///< MergeSubblockFlag[][]
diff --git a/libavcodec/vvc/dsp.c b/libavcodec/vvc/dsp.c
index 9bfa46b03d..af392f2754 100644
--- a/libavcodec/vvc/dsp.c
+++ b/libavcodec/vvc/dsp.c
@@ -44,6 +44,15 @@ static int vvc_sad(const int16_t *src0, const int16_t *src1, int dx, int dy,
return sad;
}
+static av_always_inline void unpack_mip_info(int *intra_mip_transposed_flag,
+ int *intra_mip_mode, const uint8_t mip_info)
+{
+ if (intra_mip_transposed_flag)
+ *intra_mip_transposed_flag = (mip_info >> 1) & 0x1;
+ if (intra_mip_mode)
+ *intra_mip_mode = (mip_info >> 2) & 0xf;
+}
+
typedef struct IntraEdgeParams {
uint8_t* top;
uint8_t* left;
diff --git a/libavcodec/vvc/intra_template.c b/libavcodec/vvc/intra_template.c
index 62342c8142..440ac5b6cc 100644
--- a/libavcodec/vvc/intra_template.c
+++ b/libavcodec/vvc/intra_template.c
@@ -627,8 +627,9 @@ static void FUNC(intra_pred)(const VVCLocalContext *lc, int x0, int y0,
FUNC(prepare_intra_edge_params)(lc, &edge, src, stride, x, y, w, h, c_idx, is_intra_mip, mode, ref_idx, need_pdpc);
if (is_intra_mip) {
- int intra_mip_transposed_flag = SAMPLE_CTB(fc->tab.imtf, x_cb, y_cb);
- int intra_mip_mode = SAMPLE_CTB(fc->tab.imm, x_cb, y_cb);
+ int intra_mip_transposed_flag;
+ int intra_mip_mode;
+ unpack_mip_info(&intra_mip_transposed_flag, &intra_mip_mode, intra_mip_flag);
fc->vvcdsp.intra.pred_mip((uint8_t *)src, edge.top, edge.left,
w, h, stride, intra_mip_mode, intra_mip_transposed_flag);
--
2.47.0
More information about the ffmpeg-devel
mailing list