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

[Young Han Lee]

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
> :)
>
> If you are unfamiliar with git format patch it works like this
>
> $ git add {changed files}
> $ git commit
> you will be prompted to write a brief commit message
> $ git format-patch origin
>
> then attach the output patch file to this e-mail.
>
> Thanks,
> Alex
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at mplayerhq.hu
> https://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel
>

Thank you, Alex:)

Young Han
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