[FFmpeg-devel] [PATCH] WMA Voice decoder

[Ronald S. Bultje]

Hi,

On Sat, Jan 30, 2010 at 8:06 PM, Vitor Sessak <vitor1001 at gmail.com> wrote:
> Ronald S. Bultje wrote:
>> + ? ?if (frame_desc->acb_type == 1) {
>> + ? ? ? ?for (n = 0; n < size; n++) {
>> + ? ? ? ? ? ?int pitch_sh8 = (s->last_pitch_val << 8) +
>> + ? ? ? ? ? ? ? ?((s->pitch_diff_sh16 * (block_idx * size + n)) >> 8);
>> + ? ? ? ? ? ?int pitch = (pitch_sh8 + 0x6F) >> 8;
>> + ? ? ? ? ? ?idx = (((pitch << 8) - pitch_sh8) * 8 + 0x80) >> 8;
>> + ? ? ? ? ? ?//FIXME don't call this with len=1
>> + ? ? ? ? ? ?ff_acelp_interpolatef(&excitation[n], &excitation[n - pitch],
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?ff_wmavoice_ipol1_coeffs, 17,
>> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?(idx >= 0) | (abs(idx) << 1), 9, 1);
>
> I think you can at least call this with len=s->pitch_diff_sh16 or something
> like that (since pitch_sh8 seems to change only after a certain fixed number
> of iterations). Also it will not stay in the way for SIMD optimizations.

How about this?

        int len;
        for (n = 0; n < size; n += len) {
            int next_idx_sh16;
            int abs_idx    = block_idx * size + n;
            int pitch_sh16 = (s->last_pitch_val << 16) +
                             s->pitch_diff_sh16 * abs_idx;
            int pitch      = (pitch_sh16 + 0x6FFF) >> 16;
            int idx_sh16   = ((pitch << 16) - pitch_sh16) * 8 + 0x8000;
            idx            = idx_sh16 >> 16;
            if (s->pitch_diff_sh16) {
                if (s->pitch_diff_sh16 > 0) {
                    next_idx_sh16 = (idx_sh16) &~ 0xFFFF;
                } else
                    next_idx_sh16 = (idx_sh16 + 0x10000) &~ 0xFFFF;
                len = av_clip((idx_sh16 - next_idx_sh16) /
s->pitch_diff_sh16 / 8,
                              1, size - n);
            } else
                len = size;

            ff_acelp_interpolatef(&excitation[n], &excitation[n - pitch],
                                  wmavoice_ipol1_coeffs, 17,
                                  (idx >= 0) + abs(idx) * 2, 9, len);
        }

Little bit ugly, but this is my first try which actually works.
Sometimes len is one too small, not sure why, so then
ff_acelp_interpolatef() is called twice with the same value, once with
len = one too short and once with len=1. That shouldn't be too bad. If
someone has good ideas on how to de-uglify this (or just outright
rejects it), let me know. Otherwise, it'll be part of the next patch.

(Work on aw_*() is still ongoing...)

Ronald