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mirror of https://git.ffmpeg.org/ffmpeg.git synced 2024-12-26 09:12:33 +00:00

avcodec/aom_film_grain: implement AFGS1 parsing

Based on the AOMedia Film Grain Synthesis 1 (AFGS1) spec:
  https://aomediacodec.github.io/afgs1-spec/

The parsing has been changed substantially relative to the AV1 film
grain OBU. In particular:

1. There is the possibility of maintaining multiple independent film
   grain parameter sets, and decoders/players are recommended to pick
   the one most appropriate for the intended display resolution. This
   could also be used to e.g. switch between different grain profiles
   without having to re-signal the appropriate coefficients.

2. Supporting this, it's possible to *predict* the grain coefficients
   from previously signalled parameter sets, transmitting only the
   residual.

3. When not predicting, the parameter sets are now stored as a series of
   increments, rather than being directly transmitted.

4. There are several new AFGS1-exclusive fields.

I placed this parser in its own file, rather than h2645_sei.c, since
nothing in the generic AFGS1 film grain payload is specific to T.35, and
to compartmentalize the code base.
This commit is contained in:
Niklas Haas 2024-02-26 14:12:53 +01:00
parent 1535d33818
commit f50382cba6
2 changed files with 251 additions and 0 deletions

View File

@ -29,6 +29,7 @@
#include "libavutil/imgutils.h"
#include "aom_film_grain.h"
#include "get_bits.h"
// Common/shared helpers (not dependent on BIT_DEPTH)
static inline int get_random_number(const int bits, unsigned *const state) {
@ -118,6 +119,243 @@ int ff_aom_apply_film_grain(AVFrame *out, const AVFrame *in,
return AVERROR_INVALIDDATA;
}
int ff_aom_parse_film_grain_sets(AVFilmGrainAFGS1Params *s,
const uint8_t *payload, int payload_size)
{
GetBitContext gbc, *gb = &gbc;
AVFilmGrainAOMParams *aom;
AVFilmGrainParams *fgp, *ref = NULL;
int ret, num_sets, n, i, uv, num_y_coeffs, update_grain, luma_only;
ret = init_get_bits8(gb, payload, payload_size);
if (ret < 0)
return ret;
s->enable = get_bits1(gb);
if (!s->enable)
return 0;
skip_bits(gb, 4); // reserved
num_sets = get_bits(gb, 3) + 1;
for (n = 0; n < num_sets; n++) {
int payload_4byte, payload_size, set_idx, apply_units_log2, vsc_flag;
int predict_scaling, predict_y_scaling, predict_uv_scaling[2];
int payload_bits, start_position;
start_position = get_bits_count(gb);
payload_4byte = get_bits1(gb);
payload_size = get_bits(gb, payload_4byte ? 2 : 8);
set_idx = get_bits(gb, 3);
fgp = &s->sets[set_idx];
aom = &fgp->codec.aom;
fgp->type = get_bits1(gb) ? AV_FILM_GRAIN_PARAMS_AV1 : AV_FILM_GRAIN_PARAMS_NONE;
if (!fgp->type)
continue;
fgp->seed = get_bits(gb, 16);
update_grain = get_bits1(gb);
if (!update_grain)
continue;
apply_units_log2 = get_bits(gb, 4);
fgp->width = get_bits(gb, 12) << apply_units_log2;
fgp->height = get_bits(gb, 12) << apply_units_log2;
luma_only = get_bits1(gb);
if (luma_only) {
fgp->subsampling_x = fgp->subsampling_y = 0;
} else {
fgp->subsampling_x = get_bits1(gb);
fgp->subsampling_y = get_bits1(gb);
}
fgp->bit_depth_luma = fgp->bit_depth_chroma = 0;
fgp->color_primaries = AVCOL_PRI_UNSPECIFIED;
fgp->color_trc = AVCOL_TRC_UNSPECIFIED;
fgp->color_space = AVCOL_SPC_UNSPECIFIED;
fgp->color_range = AVCOL_RANGE_UNSPECIFIED;
vsc_flag = get_bits1(gb); // video_signal_characteristics_flag
if (vsc_flag) {
int cicp_flag;
fgp->bit_depth_luma = get_bits(gb, 3) + 8;
if (!luma_only)
fgp->bit_depth_chroma = fgp->bit_depth_luma;
cicp_flag = get_bits1(gb);
if (cicp_flag) {
fgp->color_primaries = get_bits(gb, 8);
fgp->color_trc = get_bits(gb, 8);
fgp->color_space = get_bits(gb, 8);
fgp->color_range = get_bits1(gb) ? AVCOL_RANGE_JPEG : AVCOL_RANGE_MPEG;
if (fgp->color_primaries > AVCOL_PRI_NB ||
fgp->color_primaries == AVCOL_PRI_RESERVED ||
fgp->color_primaries == AVCOL_PRI_RESERVED0 ||
fgp->color_trc > AVCOL_TRC_NB ||
fgp->color_trc == AVCOL_TRC_RESERVED ||
fgp->color_trc == AVCOL_TRC_RESERVED0 ||
fgp->color_space > AVCOL_SPC_NB ||
fgp->color_space == AVCOL_SPC_RESERVED)
goto error;
}
}
predict_scaling = get_bits1(gb);
if (predict_scaling && (!ref || ref == fgp))
goto error; // prediction must be from valid, different set
predict_y_scaling = predict_scaling ? get_bits1(gb) : 0;
if (predict_y_scaling) {
int y_scale, y_offset, bits_res;
y_scale = get_bits(gb, 9) - 256;
y_offset = get_bits(gb, 9) - 256;
bits_res = get_bits(gb, 3);
if (bits_res) {
int res[14], pred, granularity;
aom->num_y_points = ref->codec.aom.num_y_points;
for (i = 0; i < aom->num_y_points; i++)
res[i] = get_bits(gb, bits_res);
granularity = get_bits(gb, 3);
for (i = 0; i < aom->num_y_points; i++) {
pred = ref->codec.aom.y_points[i][1];
pred = ((pred * y_scale + 8) >> 4) + y_offset;
pred += (res[i] - (1 << (bits_res - 1))) * granularity;
aom->y_points[i][0] = ref->codec.aom.y_points[i][0];
aom->y_points[i][1] = av_clip_uint8(pred);
}
}
} else {
aom->num_y_points = get_bits(gb, 4);
if (aom->num_y_points > 14) {
goto error;
} else if (aom->num_y_points) {
int bits_inc, bits_scaling;
int y_value = 0;
bits_inc = get_bits(gb, 3) + 1;
bits_scaling = get_bits(gb, 2) + 5;
for (i = 0; i < aom->num_y_points; i++) {
y_value += get_bits(gb, bits_inc);
if (y_value > UINT8_MAX)
goto error;
aom->y_points[i][0] = y_value;
aom->y_points[i][1] = get_bits(gb, bits_scaling);
}
}
}
if (luma_only) {
aom->chroma_scaling_from_luma = 0;
aom->num_uv_points[0] = aom->num_uv_points[1] = 0;
} else {
aom->chroma_scaling_from_luma = get_bits1(gb);
if (aom->chroma_scaling_from_luma) {
aom->num_uv_points[0] = aom->num_uv_points[1] = 0;
} else {
for (uv = 0; uv < 2; uv++) {
predict_uv_scaling[uv] = predict_scaling ? get_bits1(gb) : 0;
if (predict_uv_scaling[uv]) {
int uv_scale, uv_offset, bits_res;
uv_scale = get_bits(gb, 9) - 256;
uv_offset = get_bits(gb, 9) - 256;
bits_res = get_bits(gb, 3);
aom->uv_mult[uv] = ref->codec.aom.uv_mult[uv];
aom->uv_mult_luma[uv] = ref->codec.aom.uv_mult_luma[uv];
aom->uv_offset[uv] = ref->codec.aom.uv_offset[uv];
if (bits_res) {
int res[10], pred, granularity;
aom->num_uv_points[uv] = ref->codec.aom.num_uv_points[uv];
for (i = 0; i < aom->num_uv_points[uv]; i++)
res[i] = get_bits(gb, bits_res);
granularity = get_bits(gb, 3);
for (i = 0; i < aom->num_uv_points[uv]; i++) {
pred = ref->codec.aom.uv_points[uv][i][1];
pred = ((pred * uv_scale + 8) >> 4) + uv_offset;
pred += (res[i] - (1 << (bits_res - 1))) * granularity;
aom->uv_points[uv][i][0] = ref->codec.aom.uv_points[uv][i][0];
aom->uv_points[uv][i][1] = av_clip_uint8(pred);
}
}
} else {
int bits_inc, bits_scaling, uv_offset;
int uv_value = 0;
aom->num_uv_points[uv] = get_bits(gb, 4);
if (aom->num_uv_points[uv] > 10)
goto error;
bits_inc = get_bits(gb, 3) + 1;
bits_scaling = get_bits(gb, 2) + 5;
uv_offset = get_bits(gb, 8);
for (i = 0; i < aom->num_uv_points[uv]; i++) {
uv_value += get_bits(gb, bits_inc);
if (uv_value > UINT8_MAX)
goto error;
aom->uv_points[uv][i][0] = uv_value;
aom->uv_points[uv][i][1] = get_bits(gb, bits_scaling) + uv_offset;
}
}
}
}
}
aom->scaling_shift = get_bits(gb, 2) + 8;
aom->ar_coeff_lag = get_bits(gb, 2);
num_y_coeffs = 2 * aom->ar_coeff_lag * (aom->ar_coeff_lag + 1);
if (aom->num_y_points) {
int ar_bits = get_bits(gb, 2) + 5;
for (i = 0; i < num_y_coeffs; i++)
aom->ar_coeffs_y[i] = get_bits(gb, ar_bits) - (1 << (ar_bits - 1));
}
for (uv = 0; uv < 2; uv++) {
if (aom->chroma_scaling_from_luma || aom->num_uv_points[uv]) {
int ar_bits = get_bits(gb, 2) + 5;
for (i = 0; i < num_y_coeffs + !!aom->num_y_points; i++)
aom->ar_coeffs_uv[uv][i] = get_bits(gb, ar_bits) - (1 << (ar_bits - 1));
}
}
aom->ar_coeff_shift = get_bits(gb, 2) + 6;
aom->grain_scale_shift = get_bits(gb, 2);
for (uv = 0; uv < 2; uv++) {
if (aom->num_uv_points[uv] && !predict_uv_scaling[uv]) {
aom->uv_mult[uv] = get_bits(gb, 8) - 128;
aom->uv_mult_luma[uv] = get_bits(gb, 8) - 128;
aom->uv_offset[uv] = get_bits(gb, 9) - 256;
}
}
aom->overlap_flag = get_bits1(gb);
aom->limit_output_range = get_bits1(gb);
// use first set as reference only if it was fully transmitted
if (n == 0)
ref = fgp;
payload_bits = get_bits_count(gb) - start_position;
if (payload_bits > payload_size * 8)
goto error;
skip_bits(gb, payload_size * 8 - payload_bits);
}
return 0;
error:
memset(s, 0, sizeof(*s));
return AVERROR_INVALIDDATA;
}
int ff_aom_attach_film_grain_sets(const AVFilmGrainAFGS1Params *s, AVFrame *frame)
{
AVFilmGrainParams *fgp;
if (!s->enable)
return 0;
for (int i = 0; i < FF_ARRAY_ELEMS(s->sets); i++) {
if (s->sets[i].type != AV_FILM_GRAIN_PARAMS_AV1)
continue;
fgp = av_film_grain_params_create_side_data(frame);
if (!fgp)
return AVERROR(ENOMEM);
memcpy(fgp, &s->sets[i], sizeof(*fgp));
}
return 0;
}
// Taken from the AV1 spec. Range is [-2048, 2047], mean is 0 and stddev is 512
static const int16_t gaussian_sequence[2048] = {
56, 568, -180, 172, 124, -84, 172, -64, -900, 24, 820,

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@ -30,9 +30,22 @@
#include "libavutil/film_grain_params.h"
typedef struct AVFilmGrainAFGS1Params {
int enable;
AVFilmGrainParams sets[8];
} AVFilmGrainAFGS1Params;
// Synthesizes film grain on top of `in` and stores the result to `out`. `out`
// must already have been allocated and set to the same size and format as `in`.
int ff_aom_apply_film_grain(AVFrame *out, const AVFrame *in,
const AVFilmGrainParams *params);
// Parse AFGS1 parameter sets from an ITU-T T.35 payload. Returns 0 on success,
// or a negative error code.
int ff_aom_parse_film_grain_sets(AVFilmGrainAFGS1Params *s,
const uint8_t *payload, int payload_size);
// Attach all valid film grain param sets to `frame`.
int ff_aom_attach_film_grain_sets(const AVFilmGrainAFGS1Params *s, AVFrame *frame);
#endif /* AVCODEC_AOM_FILM_GRAIN_H */