Re: [FFmpeg-devel] [PATCH] checkasm/hevc_deblock: add luma test

["Martin Storsjö" <martin@martin.st>]

On Tue, 5 Dec 2023, J. Dekker wrote:

> Signed-off-by: J. Dekker <jdek@itanimul.li>
> ---
> tests/checkasm/hevc_deblock.c | 110 ++++++++++++++++++++++++++++++++--
> 1 file changed, 106 insertions(+), 4 deletions(-)
>
> Yes, this only supports 8bit. 10/12bit should be trivial, will add if this
> looks reasonable (I checked code paths using gdb, and as far as I can tell it
> does test all three). Tested on known good x86 asm.

Overall I think this looks mostly good.

A few pointers for things that could be improved later, in addition to 
10/12 bit support, and a few minor things to fix before pushing:

> diff --git a/tests/checkasm/hevc_deblock.c b/tests/checkasm/hevc_deblock.c
> index 66fc8d5646..3f970a470a 100644
> --- a/tests/checkasm/hevc_deblock.c
> +++ b/tests/checkasm/hevc_deblock.c
> @@ -29,8 +29,8 @@
> static const uint32_t pixel_mask[3] = { 0xffffffff, 0x03ff03ff, 0x0fff0fff };
>
> #define SIZEOF_PIXEL ((bit_depth + 7) / 8)
> -#define BUF_STRIDE (8 * 2)
> -#define BUF_LINES (8)
> +#define BUF_STRIDE (16 * 2)
> +#define BUF_LINES (16)
> #define BUF_OFFSET (BUF_STRIDE * BUF_LINES)
> #define BUF_SIZE (BUF_STRIDE * BUF_LINES + BUF_OFFSET * 2)

For these calculations, make sure to check that things stay within the 
expected bounds for all reads/writes, if you extend it to 10/12 bits 
later.

> @@ -88,14 +88,116 @@ static void check_deblock_chroma(HEVCDSPContext *h, int bit_depth)
>     }
> }
>
> +// line zero
> +#define P3 buf[-4 * xstride]
> +#define P2 buf[-3 * xstride]
> +#define P1 buf[-2 * xstride]
> +#define P0 buf[-1 * xstride]
> +#define Q0 buf[0 * xstride]
> +#define Q1 buf[1 * xstride]
> +#define Q2 buf[2 * xstride]
> +#define Q3 buf[3 * xstride]
> +
> +// line three. used only for deblocking decision

I don't immediately see what these comments about line zero and line three 
mean here.

> +#define TP3 buf[-4 * xstride + 3 * ystride]
> +#define TP2 buf[-3 * xstride + 3 * ystride]
> +#define TP1 buf[-2 * xstride + 3 * ystride]
> +#define TP0 buf[-1 * xstride + 3 * ystride]
> +#define TQ0 buf[0  * xstride + 3 * ystride]
> +#define TQ1 buf[1  * xstride + 3 * ystride]
> +#define TQ2 buf[2  * xstride + 3 * ystride]
> +#define TQ3 buf[3  * xstride + 3 * ystride]

Hmm, this seems to be unused currently?

> +
> +static void randomize_luma_buffers(int type, uint8_t *buf, ptrdiff_t xstride, ptrdiff_t ystride)
> +{
> +    int i;
> +    buf += BUF_OFFSET;
> +    switch (type) {
> +    case 0: // strong
> +        for (i = 0; i < 16; i++) {
> +            P3 = P2 = P1 = P0 = 64;
> +            Q0 = Q1 = Q2 = Q3 = 80;
> +            buf += ystride;
> +        }
> +        break;
> +    case 1: // weak
> +        for (i = 0; i < 16; i++) {
> +            P3 = P2 = 60; P1 = P0 = 64;
> +            Q0 = Q1 = 74; Q2 = Q3 = 80;
> +            buf += ystride;
> +        }

These two aren't very random right now :-) Can we fit within the same 
criteria while keeping things somewhat random? E.g. "P3 = P2 + (rand() % 
2*range) - range", or something along those lines?

> +static void check_deblock_luma(HEVCDSPContext *h, int bit_depth)
> +{
> +    const char *type;
> +    const char *types[3] = { "strong", "normal", "skip" };
> +    int beta;
> +    int32_t tc[2] = { 0, 0 };
> +    // no_p, no_q can only be { 0,0 } for the simpler assembly (non *_c
> +    // variant) functions, see deblocking_filter_CTB() in hevc_filter.c

Can we extend this to test the _c variant as well?

> +    uint8_t no_p[2] = { 0, 0 };
> +    uint8_t no_q[2] = { 0, 0 };
> +    LOCAL_ALIGNED_32(uint8_t, buf0, [BUF_SIZE]);
> +    LOCAL_ALIGNED_32(uint8_t, buf1, [BUF_SIZE]);
> +
> +    declare_func(void, uint8_t *pix, ptrdiff_t stride, int beta, int32_t *tc, uint8_t *no_p, uint8_t *no_q);
> +
> +    for (int j = 0; j < 3; j++) {
> +        beta = (j == 3) ? 0 : 32; // beta easy way to turn off filtering

We never hit j==3 here, did you intend to have a fourth type included 
here?

Can we use a less hardcoded beta value here, while still triggering the 
right cases?

> +        type = types[j];
> +
> +        // see betatable[] in hevc_filter.c
> +        tc[0] = (rnd() & 63) + (rnd() & 1);
> +        tc[1] = (rnd() & 63) + (rnd() & 1);

Hmm, I don't immediately see how the tc[] values relate to betatable[] on 
a first glance

// Martin

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