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

[Vladimir Voroshilov]

2008/5/22 Michael Niedermayer <michaelni at gmx.at>:
> On Mon, May 19, 2008 at 08:26:27AM +0700, Vladimir Voroshilov wrote:
>> 2008/5/19 Michael Niedermayer <michaelni at gmx.at>:
>> > On Mon, May 19, 2008 at 12:47:16AM +0700, Vladimir Voroshilov wrote:
>> >> 2008/5/18 Michael Niedermayer <michaelni at gmx.at>:
>> >> > On Sun, May 18, 2008 at 01:23:20PM +0700, Vladimir Voroshilov wrote:
>> >>
>> >> [...]
>> >>
>> >> >> What about such uniform routine?
>> >> >
>> >> > I think its a mess.
>> >> >
>> >> > tab, tab2, pulse_count, bits should be arguments to the function not some
>> >> > enum which sets them in a switch()
>> >> >
>> >>
>> >> like this?
>> > [...]
>> >> +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
>> >> +};
>> >> +
>> >> +const uint8_t fc_2pulses_9bits_track1[16] =
>> >> +{
>> >> +    1,  3,
>> >> +    6,  8,
>> >> +    11, 13,
>> >> +    16, 18,
>> >> +    21, 23,
>> >> +    26, 28,
>> >> +    31, 33,
>> >> +    36, 38
>> >> +};
>> >> +
>> >> +const uint8_t fc_4pulses_8bits_tracks_13[16] =
>> >> +{
>> >> +  0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75,
>> >> +};
>> >> +
>> >> +const uint8_t fc_4pulses_8bits_track_4[32] =
>> >> +{
>> >> +    3,  4,
>> >> +    8,  9,
>> >> +    13, 14,
>> >> +    18, 19,
>> >> +    23, 24,
>> >> +    28, 29,
>> >> +    33, 34,
>> >> +    38, 39,
>> >> +    43, 44,
>> >> +    48, 49,
>> >> +    53, 54,
>> >> +    58, 59,
>> >> +    63, 64,
>> >> +    68, 69,
>> >> +    73, 74,
>> >> +    78, 79,
>> >> +};
>> >> +
>> >> +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
>> >> +};
>> >
>> > Are the tables which use gray_decode also used without it?
>> > If no merging gray_decode into them would reduce complexity.
>>
>> Due to error in the second table, it is not used
>> anywhere except G.729D, first can be reused in AMR @5.9k
>> I'd applied gray coding to both and add _gray suffix.
>>
>> *_track1 (without gray coding) is kept as copy.
>> Also kept gray_decoding table under #if 0
>
> [...]
>
>> +void ff_acelp_fc_enchance_harmonics(
>> +        int16_t* fc_v,
>> +        int pitch_delay,
>> +        int16_t gain_pitch,
>> +        int length)
>> +{
>> +    int i;
>> +
>> +    for(i=pitch_delay; i<length;i++)
>> +        fc_v[i] += (fc_v[i - pitch_delay] * gain_pitch) >> 14;
>> +}
>> +
>> +void ff_acelp_build_excitation(
>> +        int16_t* exc,
>> +        const int16_t *ac_v,
>> +        const int16_t *fc_v,
>> +        int16_t gp,
>> +        int16_t gc,
>> +        int subframe_size)
>> +{
>> +    int i;
>> +
>> +    // Clipping required here; breaks OVERFLOW test.
>> +    for(i=0; i<subframe_size; i++)
>> +        exc[i] = av_clip_int16((ac_v[i] * gp + fc_v[i] * gc + 0x2000) >> 14);
>> +}
>
> duplicate, these 2 functions do the same, that is a wheighted sum of 2
> vectors.
>

agree.
As i see

ff_acelp_fc_enchance_harmonics(fc_v, pitch_delay, gain_pitch, length)

is equal to

ff_acelp_build_excitation(fc_v+pitch_delay, fc_v+pitch_delay,
fc,1<<14, gain_pitch, length-pitch_delay);

but what should i do with rounding ?

what about adding additional parameter (const summand) to
ff_acelp_build_excitation
I.e. something like:

void ff_acelp_build_excitation(
        int16_t* exc,
        const int16_t *ac_v,
        const int16_t *fc_v,
        int16_t gp,
        int16_t gc,
        int16_t summand,
        int subframe_size)
{
    int i;

    // Clipping required here; breaks OVERFLOW test.
    for(i=0; i<subframe_size; i++)
        exc[i] = av_clip_int16((ac_v[i] * gp + fc_v[i] * gc + summand) >> 14);
}

What about renaming ff_acelp_build_excitation like ff_acelp_weighted_vector_sum
(and subframe_size -> length, ac_v -> vect_a, fc_v -> vect_b, gc ->
weight_coeff_a, gp -> weight_coeff_b)?

P.S. "summand" don't look like the best name too.

-- 
Regards,
Vladimir Voroshilov mailto:voroshil at gmail.com
JID: voroshil at gmail.com, voroshil at jabber.ru
ICQ: 95587719