[FFmpeg-devel] [PATCH] Common ACELP code & G.729 [3/7] - vectors operations

[Michael Niedermayer]

On Fri, May 02, 2008 at 06:43:18PM +0700, Vladimir Voroshilov wrote:
> This patch contains routines for operating with adaptive and algebraic vectors.
> 
> FIR filter was moved here.
> It now does not use any "frac=-frac" or "if(frac<9)" and can be called
> as foo(delay/6, delay%6).
> This possibility was not obvious for me due to loop asymmetry,
> introduced in reference code (and in specification too)
> to avoid "out of bounds" error.

[...]
> +static const uint8_t mul_5x[8] = {0, 5, 10, 15, 20, 25, 30, 35};

*5 should do :)



> +
> +static const uint8_t fc_2pulses_9bits_track1[16] =
> +{
> +  1, 3, 6, 8, 11, 13, 16, 18, 21, 23, 26, 28, 31, 33, 36, 38
> +};

((x*5)>>1)+1



> +
> +/*
> +  (EE) This table (from reference code) does not comply with specifiation !
> +  Specification contains following table:
> +   0,  1,   2,  4,
> +   5,  6,   7,  9,
> +   10, 11, 12, 14,
> +   15, 16, 17, 19,
> +   20, 21, 22, 24,
> +   25, 26, 27, 29,
> +   30, 31, 32, 34,
> +   35, 36, 37, 39,
> +*/
> +static const uint8_t fc_2pulses_9bits_track2[32] =
> +{
> +   0,  2,   4,
> +   5,  7,   9,
> +   10, 12, 14,
> +   15, 17, 19,
> +   20, 22, 24,
> +   25, 27, 29,
> +   30, 32, 34,
> +   35, 37, 39,
> +   1,
> +   6,
> +   11,
> +   16,
> +   21,
> +   26,
> +   31,
> +   36
> +};
> +

> +static uint8_t gray_decode[32] =
> +{
> +    0,  1,  3,  2,  7,  6,  4,  5,
> +   15, 14, 12, 13,  8,  9, 11, 10,
> +   31, 30, 28, 29, 24, 25, 27, 26,
> +   16, 17, 19, 18, 23, 22, 20, 21
> +};

this is just x^(x>>1)
of course only replace the table with above if its smaller/faster, same
applies to the other suggested replacements for the tables


[...]
> +void ff_acelp_fc_4pulses_13bits(
> +        int16_t* fc_v,
> +        int fc_index,
> +        int pulses_signs)
> +{
> +    int i;
> +    int index;
> +
> +    for(i=0; i<3; i++)
> +    {
> +        index = i + mul_5x[fc_index & 7];
> +        fc_v[ index ] += (pulses_signs & 1) ? 8191 : -8192; // +/-1 in (2.13)
> +
> +        fc_index >>= 3;
> +        pulses_signs >>= 1;
> +    }
> +
> +    index = 3 + (fc_index & 1) + mul_5x[(fc_index>>1) & 7];
> +    fc_v[ index ] += (pulses_signs & 1) ? 8191 : -8192;
> +}
> +

> +void ff_acelp_fc_2pulses_9bits_g729d(
> +        int16_t* fc_v,
> +        int fc_index,
> +        int pulses_signs)
> +{
> +    int index;
> +
> +    index = fc_2pulses_9bits_track1[gray_decode[fc_index & 15]];
> +    fc_v[ index ] += (pulses_signs & 1) ? 8191 : -8192; // +/-1 in (2.13)
> +
> +    pulses_signs >>= 1;
> +    fc_index >>= 4;
> +
> +    index = fc_2pulses_9bits_track2[gray_decode[fc_index & 31]];
> +    fc_v[ index ] += (pulses_signs & 1) ? 8191 : -8192; // +/-1 in (2.13)
> +}
> +

> +void ff_acelp_fc_4pulses_21bits(
> +        int16_t* fc_v,
> +        int fc_index,
> +        int pulses_signs)
> +{
> +    int i;
> +    int index;
> +
> +    for(i=0; i<3; i++)
> +    {
> +        index = i + 5 *(fc_index & 15);
> +        fc_v[ index ] += (pulses_signs & 1) ? 8191 : -8192; // +/-1 in (2.13)
> +
> +        fc_index >>= 4;
> +        pulses_signs >>= 1;
> +    }
> +
> +    index = 3 + (fc_index & 1);
> +    fc_index >>= 1;
> +    index += 5 * (fc_index & 15);
> +    fc_v[ index ] += (pulses_signs & 1) ? 8191 : -8192;
> +}
> +

duplicate of ff_acelp_fc_4pulses_13bits()
also the 
fc_v[ index ] += (pulses_signs & 1) ? 8191 : -8192;
stuff is duplicated all over the place

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

No snowflake in an avalanche ever feels responsible. -- Voltaire
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