[FFmpeg-devel] [PATCH] Implement AAC Long Term Prediction (LTP) decoding module

[Alex Converse]

On Mon, Feb 14, 2011 at 1:12 AM, Young Han Lee <cpumaker at gmail.com> wrote:
> On Mon, Feb 14, 2011 at 5:37 PM, Alex Converse <alex.converse at gmail.com>wrote:
>
>> On Mon, Feb 14, 2011 at 12:15 AM, Young Han Lee <cpumaker at gmail.com>
>> wrote:
>> > On Mon, Feb 14, 2011 at 4:55 PM, Rob <robert.swain at gmail.com> wrote:
>> >
>> >> On 14 February 2011 02:27, Young Han Lee <cpumaker at gmail.com> wrote:
>> >> > On Mon, Feb 14, 2011 at 6:46 AM, Alex Converse <
>> alex.converse at gmail.com
>> >> >wrote:
>> >> >
>> >> >> On Sun, Feb 13, 2011 at 5:56 AM, Young Han Lee <cpumaker at gmail.com>
>> >> wrote:
>> >> >> >
>> >> >> > any comment about this?
>> >> >>
>> >> >> It looks good, one last thought
>> >> >>
>> >> >> +static void windowing_and_mdct_ltp(AACContext *ac, float *out,
>> >> >> + ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? float *in,
>> IndividualChannelStream
>> >> >> *ics)
>> >> >> +{
>> >> >> + ? ?const float * lwindow ? ? ?= ics->use_kb_window[0] ?
>> >> >> ff_aac_kbd_long_1024 : ff_sine_1024;
>> >> >> + ? ?const float * swindow ? ? ?= ics->use_kb_window[0] ?
>> >> >> ff_aac_kbd_short_128 : ff_sine_128;
>> >> >> + ? ?const float * lwindow_prev = ics->use_kb_window[1] ?
>> >> >> ff_aac_kbd_long_1024 : ff_sine_1024;
>> >> >> + ? ?const float * swindow_prev = ics->use_kb_window[1] ?
>> >> >> ff_aac_kbd_short_128 : ff_sine_128;
>> >> >> + ? ?float * buf = ac->buf_mdct;
>> >> >>
>> >> >> buf is the same as in should lets just drop buf and call it in.
>> >> >>
>> >> >>
>> >> > Is it just use the "ac->buf_mdct" instead of "*buf"
>> >> > If yes, I'll change the rest of "*buf".
>> >>
>> >> In apply_ltp(), predTime is ac->buf_mdct. predTime is pass to
>> >> windowing_and_mdct_ltp() as the 'in' argument. Within
>> >> windowing_and_mdct_ltp() you also made another variable called buf
>> >> that points to ac->buf_mdct. As buf == 'in', buf is redundant and it
>> >> would be clearer if 'in' were used for both throughout the function.
>> >> e.g.
>> >>
>> >> + ? ? ? ?ac->dsp.vector_fmul(ac->buf_mdct, in, lwindow_prev, 1024);
>> >>
>> >> could be
>> >>
>> >> + ? ? ? ?ac->dsp.vector_fmul(in, in, lwindow_prev, 1024);
>> >>
>> >> as in == ac->buf_mdct and this change makes it clearer tot he reader
>> >> that they are the same.
>> >>
>> >> Regards,
>> >> Rob
>> >> _______________________________________________
>> >> ffmpeg-devel mailing list
>> >> ffmpeg-devel at mplayerhq.hu
>> >> https://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel
>> >>
>> >
>> > I misunderstood it.
>> > now I fix it.
>> >
>>
>> Thank you.
>>
>> In revision 9 "ret" shrunk from 2048 to 1024? Ret needs to be 2048
>> samples long for SBR. Was the shrinkage intentional?
>>
>>
> No. I didn't know that ret needs to be 2048 in case of SBR.
> I'll change it.sorry
>
>
>> Also please submit a patch with git format-patch so I can push this to git
>> :)
>>

Pushed with cosmetics

Thanks for your contribution