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

Young Han Lee cpumaker
Sun Feb 13 14:56:34 CET 2011

On Fri, Feb 11, 2011 at 10:46 AM, Young Han Lee <cpumaker at gmail.com> wrote:

> On Thu, Feb 10, 2011 at 6:05 PM, Rob <robert.swain at gmail.com> wrote:
>> On 10 February 2011 09:46, Rob <robert.swain at gmail.com> wrote:
>> > On 10 February 2011 06:23, Alex Converse <alex.converse at gmail.com>
>> wrote:
>> >> This version looks good.
>> >>
>> >> Does anyone else have comments?
>> >
>> > I'll have a look over it shortly.
>> My only concerns are that the expansion/addition of data arrays is
>> significant. There's a 1024 element float array, a 3072 element
>> int16_t array and an additional 1024 elements in another float array.
>> I'm not saying that this needs to block merging, but if there is a way
>> to improve it, perhaps we can add some comments as to how.
> one of 1024 element float array (saved_ltp) is merged.
> I'm thinking about how to merge the rest of additional data arrays
> but I don't have good idea right now.
> And the "ret" data array is reduced to 1024.
> I think it could be missed when the imdct_half was implemented.
> please check this out.
> Is the int16_t array really needed? We output float anyway don't we so
>> perhaps there is a way to translate the method to use float all the
>> way through. I seem to remember when I switched to using imdct_half
>> and vector_fmul I was able to reduce the array sizes somewhat. Is
>> there any possibility of this for this ltp code? Things like that.
> In the MPEG document, "short" type was recommended but,
> it is not a big problem to change the type to float.
> However, the array size will be double.
> Do I change to float or not?
> I'll consider about the possibility of method you used.
> but it needs time :).
> Generally, the code looks very neat and gets the OK from me as long as
>> it has been tested with relevant clips and works. :) Good job!
>> Regards,
>> Rob
>> _______________________________________________
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>> ffmpeg-devel at mplayerhq.hu
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> Regards,
> Young Han

any comment about this?
If I should do something to apply it, please let me know.

Young Han

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