[FFmpeg-devel] AAC decoder round 5

[Michael Niedermayer]

On Fri, Aug 08, 2008 at 02:16:42PM +0100, Robert Swain wrote:
> 2008/8/7 Robert Swain <robert.swain at gmail.com>:
> > 2008/8/7 Michael Niedermayer <michaelni at gmx.at>:
> >> On Thu, Aug 07, 2008 at 04:04:44PM +0100, Robert Swain wrote:
> >>> 2008/8/6 Michael Niedermayer <michaelni at gmx.at>:
> >>> > On Wed, Aug 06, 2008 at 12:32:32AM +0100, Robert Swain wrote:
> >>> > [...]
> >>> >
> >>> >> Index: libavcodec/aactab.c
> >>> >> ===================================================================
> >>> >> --- libavcodec/aactab.c       (revision 14625)
> >>> >> +++ libavcodec/aactab.c       (working copy)
> >>>
> >>> [...]
> >>>
> >>> >> +DECLARE_ALIGNED(16, float,  ff_aac_kbd_long_1024[1024]);
> >>> >> +DECLARE_ALIGNED(16, float,  ff_aac_kbd_short_128[128]);
> >>> >> +DECLARE_ALIGNED(16, float, ff_aac_sine_long_1024[1024]);
> >>> >> +DECLARE_ALIGNED(16, float, ff_aac_sine_short_128[128]);
> >>> >> +
> >>> >> +const uint8_t ff_aac_num_swb_1024[] = {
> >>> >> +    41, 41, 47, 49, 49, 51, 47, 47, 43, 43, 43, 40
> >>> >> +};
> >>> >> +
> >>> >> +const uint8_t ff_aac_num_swb_128[] = {
> >>> >> +    12, 12, 12, 14, 14, 14, 15, 15, 15, 15, 15, 15
> >>> >> +};
> >>> >> +
> >>> >>  const uint32_t ff_aac_scalefactor_code[121] = {
> >>> >>      0x3ffe8, 0x3ffe6, 0x3ffe7, 0x3ffe5, 0x7fff5, 0x7fff1, 0x7ffed, 0x7fff6,
> >>> >>      0x7ffee, 0x7ffef, 0x7fff0, 0x7fffc, 0x7fffd, 0x7ffff, 0x7fffe, 0x7fff7,
> >>> >
> >>> >
> >>> >> @@ -795,4 +809,90 @@
> >>> >>       4064.0312908,  4074.6805676,  4085.3368071,  4096.0000000,
> >>> >>  };
> >>> >>
> >>> >> +/* [ 0, 255] scale factor decoding when using C dsp.float_to_int16
> >>> >> + * [60, 315] scale factor decoding when using SIMD dsp.float_to_int16
> >>> >> + * [45, 300] intensity stereo position decoding mapped in reverse order i.e. 0->300, 1->299, ..., 254->46, 255->45
> >>> >> + */
> >>> >
> >>> > not doxygen compat, no description of what the table actually contains.
> >>>
> >>> Comment quoted above improved. Does your statement apply to all of the
> >>> above or just the comment for pow2sf_tab[]?
> >>
> >> i just meant pow2sf_tab but the ff_aac_num_swb_128/1024 could also benefit
> >> from a little doxy, the windows are obvious at least to me so i dont care
> >> if they get a doxy or not.
> >
> > I'll put that swb/sfb documentation next to all the *swb* arrays plus
> > a comment about what the offsets are and so on. I'll just have a look
> > through and see what I think is non-obvious.
> 
> How about the attached?

well, ok but iam not really sure if this is undertstandable ..

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

There will always be a question for which you do not know the correct awnser.
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