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

[Aurelien Jacobs]

On Wed, Nov 08, 2017 at 06:26:03PM +0100, Michael Niedermayer wrote:
> 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 *

Right.

> [...]
> > +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

Indeed, now that I moved the shift inside the code.

> [...]
> > +/*
> > + * 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 &

OK. And there was a second one that I changed as well.

> > +}
> > +
> > +/*
> > + * 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

If you insist on this I will of course change it, but hey, we require
a C99 compiler since a long time and we use so many features of C99
that I really don't get why we couldn't use "for (int".
I can't imagine that any relevant C compiler would not support this
nowadays !
What I propose is to get this in as is, and see if anyone encounter
issue with any compiler. If any issue arise, I will of course send a
patch to fix it.

Here is an updated patch.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-aptx-implement-the-aptX-bluetooth-codec.patch
Type: text/x-diff
Size: 35627 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20171108/3d96fa5e/attachment.patch>