Re: [FFmpeg-devel] [PATCH] checkasm: add support for vvc alf

["Martin Storsjö" <martin@martin.st>]

On Sun, 26 Feb 2023, Nuo Mi wrote:

> +#include <string.h>
> +
> +#include "libavutil/intreadwrite.h"
> +#include "libavutil/mem_internal.h"
> +
> +#include "libavcodec/avcodec.h"
> +
> +#include "libavcodec/vvcdsp.h"
> +#include "libavcodec/vvcdec.h"
> +
> +#include "checkasm.h"
> +
> +static const uint32_t pixel_mask[3] = { 0xffffffff, 0x03ff03ff, 0x0fff0fff };
> +
> +#define SIZEOF_PIXEL ((bit_depth + 7) / 8)
> +#define PIXEL_STRIDE (ALF_SUBBLOCK_SIZE + 2 * ALF_PADDING_SIZE)
> +#define BUF_SIZE (PIXEL_STRIDE * (MAX_CTU_SIZE + 3 * 2) * 2) //+3 * 2 for top and bottom row, *2 for high bit depth
> +#define LUMA_PARAMS_SIZE (ALF_SUBBLOCK_SIZE / 4 * ALF_SUBBLOCK_SIZE / 4 * ALF_NUM_COEFF_LUMA)
> +
> +#define randomize_buffers(buf0, buf1, size)                 \
> +    do {                                                    \
> +        uint32_t mask = pixel_mask[(bit_depth - 8) >> 1];   \
> +        int k;                                              \
> +        for (k = 0; k < size; k += 4) {                     \
> +            uint32_t r = rnd() & mask;                      \
> +            AV_WN32A(buf0 + k, r);                          \
> +            AV_WN32A(buf1 + k, r);                          \
> +        }                                                   \
> +    } while (0)
> +
> +#define randomize_buffers2(buf, size, filter)               \
> +    do {                                                    \
> +        int k;                                              \
> +        if (filter) {                                       \
> +            for (k = 0; k < size; k++) {                    \
> +                uint8_t r = rnd();                          \
> +                buf[k] = r;                                 \
> +            }                                               \
> +        } else {                                            \
> +            for (k = 0; k < size; k++) {                    \
> +                int16_t r = rnd();                          \
> +                buf[k] = r;                                 \
> +            }                                               \
> +        }                                                   \
> +    } while (0)

I don't quite see the point of the extra uint8_t/int16_t variable r here - 
you could just as well assign it directly to buf[k], no? Unless you 
specifically want the effect where you're narrowing the random value to a 
smaller range beforehand.

> +
> +static void check_alf_luma_filter(VVCDSPContext *c, const int bit_depth)
> +{
> +    LOCAL_ALIGNED_32(uint8_t, dst0, [BUF_SIZE]);
> +    LOCAL_ALIGNED_32(uint8_t, dst1, [BUF_SIZE]);
> +    LOCAL_ALIGNED_32(uint8_t, src0, [BUF_SIZE]);
> +    LOCAL_ALIGNED_32(uint8_t, src1, [BUF_SIZE]);
> +    int8_t filter[LUMA_PARAMS_SIZE];
> +    int16_t clip[LUMA_PARAMS_SIZE];
> +    ptrdiff_t stride = PIXEL_STRIDE * SIZEOF_PIXEL;
> +    int offset = (3 * PIXEL_STRIDE + 3) * SIZEOF_PIXEL;
> +
> +    declare_func_emms(AV_CPU_FLAG_AVX2, void, uint8_t *dst, ptrdiff_t dst_stride, const uint8_t *src, ptrdiff_t src_stride,
> +        int width, int height, const int8_t *filter, const int16_t *clip);
> +
> +    randomize_buffers(src0, src1, BUF_SIZE);
> +    randomize_buffers2(filter, LUMA_PARAMS_SIZE, 1);
> +    randomize_buffers2(clip, LUMA_PARAMS_SIZE, 2);

Here, both invocations of randomize_buffers2 are called with filter=1 or 
2, both which will pick the "if (filter) {" case, so the else in 
randomize_buffers2 is unused?

> +
> +    for (int h = 4; h < ALF_SUBBLOCK_SIZE; h += 4) {
> +        for (int w = 4; w < ALF_SUBBLOCK_SIZE; w += 4) {

Wouldn't you want to use <= instead of < for the comparisons here? I don't 
know vvc so I can't say for sure, but that would seem logical to me.

Are all aspect ratio combinations allowed here? E.g. the log mentions that 
you're testing 28x4 blocks. In dav1d, similar cases use logic of testing w 
in the range of [h/4, h*4] (plus limited to e.g. [4,64] at the same time). 
That would reduce the number of combinations to test, if they aren't 
really valid in practice.

> +            if (check_func(c->alf.filter[LUMA], "vvc_alf_filter_luma_%dx%d_%d", w, h, bit_depth)) {
> +                memset(dst0, 0, BUF_SIZE);
> +                memset(dst1, 0, BUF_SIZE);
> +                call_ref(dst0, stride, src0 + offset, stride, w, h, filter, clip);
> +                call_new(dst1, stride, src1 + offset, stride, w, h, filter, clip);
> +                for (int i = 0; i < h; i++) {
> +                    if (memcmp(dst0 + i * stride, dst1 + i * stride, w * SIZEOF_PIXEL))
> +                        fail();
> +                }
> +                bench_new(dst1, stride, src1 + offset, stride, w, h, filter, clip);
> +            }
> +            if (check_func(c->alf.filter[CHROMA], "vvc_alf_filter_chroma_%dx%d_%d", w, h, bit_depth)) {
> +                memset(dst0, 0, BUF_SIZE);
> +                memset(dst1, 0, BUF_SIZE);
> +                call_ref(dst0, stride, src0 + offset, stride, w, h, filter, clip);
> +                call_new(dst1, stride, src1 + offset, stride, w, h, filter, clip);
> +                for (int i = 0; i < h; i++) {
> +                    if (memcmp(dst0 + i * stride, dst1 + i * stride, w * SIZEOF_PIXEL))
> +                        fail();
> +                }
> +                bench_new(dst1, stride, src1 + offset, stride, w, h, filter, clip);
> +            }
> +        }
> +    }
> +}
> +
> +void checkasm_check_vvc_alf(void)
> +{
> +    int bit_depth = 10;
> +    VVCDSPContext h;
> +    ff_vvc_dsp_init(&h, bit_depth);
> +    check_alf_luma_filter(&h, bit_depth);
> +    report("alf_filter");

Is 10 bits the only currently valid bitdepth here? Otherwise I think we 
should include all of them, even if there's only assembly for one case at 
the moment. (The pixel_mask seems to assume 8/10/12 bits.)

// Martin

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