[FFmpeg-devel] [PATCH 1/2] aptx: implement the aptX bluetooth codec

[Michael Niedermayer]

On Wed, Nov 08, 2017 at 02:06:09PM +0100, Aurelien Jacobs wrote:
[...]
> +typedef const struct {
> +    const int32_t *quantize_intervals;
> +    const int32_t *invert_quantize_dither_factors;
> +    const int32_t *quantize_dither_factors;

> +    const int32_t *quantize_factor_select_offset;

this would fit in int16_t *


> +    int tables_size;
> +    int32_t quantized_bits;
> +    int32_t prediction_order;
> +} ConstTables;
> +
> +static ConstTables tables[NB_SUBBANDS] = {
> +    [LF]  = { quantize_intervals_LF,
> +              invert_quantize_dither_factors_LF,
> +              quantize_dither_factors_LF,
> +              quantize_factor_select_offset_LF,
> +              FF_ARRAY_ELEMS(quantize_intervals_LF),
> +              7, 24 },
> +    [MLF] = { quantize_intervals_MLF,
> +              invert_quantize_dither_factors_MLF,
> +              quantize_dither_factors_MLF,
> +              quantize_factor_select_offset_MLF,
> +              FF_ARRAY_ELEMS(quantize_intervals_MLF),
> +              4, 12 },
> +    [MHF] = { quantize_intervals_MHF,
> +              invert_quantize_dither_factors_MHF,
> +              quantize_dither_factors_MHF,
> +              quantize_factor_select_offset_MHF,
> +              FF_ARRAY_ELEMS(quantize_intervals_MHF),
> +              2, 6 },
> +    [HF]  = { quantize_intervals_HF,
> +              invert_quantize_dither_factors_HF,
> +              quantize_dither_factors_HF,
> +              quantize_factor_select_offset_HF,
> +              FF_ARRAY_ELEMS(quantize_intervals_HF),
> +              3, 12 },
> +};
> +

> +static const int32_t quantization_factors[32] = {
> +    2048, 2093, 2139, 2186, 2233, 2282, 2332, 2383,
> +    2435, 2489, 2543, 2599, 2656, 2714, 2774, 2834,
> +    2896, 2960, 3025, 3091, 3158, 3228, 3298, 3371,
> +    3444, 3520, 3597, 3676, 3756, 3838, 3922, 4008,
> +};

this too would fir in int16_t

[...]
> +/*
> + * Push one sample into a circular signal buffer.
> + */
> +av_always_inline
> +static void aptx_qmf_filter_signal_push(FilterSignal *signal, int32_t sample)
> +{
> +    signal->buffer[signal->pos            ] = sample;
> +    signal->buffer[signal->pos+FILTER_TAPS] = sample;
> +    signal->pos = (signal->pos + 1) % FILTER_TAPS;

% could be replaced by &


> +}
> +
> +/*
> + * Compute the convolution of the signal with the coefficients, and reduce
> + * to 24 bits by applying the specified right shifting.
> + */
> +av_always_inline
> +static int32_t aptx_qmf_convolution(FilterSignal *signal,
> +                                    const int32_t coeffs[FILTER_TAPS],
> +                                    int shift)
> +{
> +    int32_t *sig = &signal->buffer[signal->pos];
> +    int64_t e = 0;
> +

> +    for (int i = 0; i < FILTER_TAPS; i++)

"for (int" is something we avoided as some comilers didnt like it,
iam not sure if this is still true but there are none in the codebase

also a fate test for this would be a good idea

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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