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Topic: FAAD2 HE-AAC with SBR ext Chirp noise  (Read 2257 times) previous topic - next topic

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  • tuanpm
  • [*]
FAAD2 HE-AAC with SBR ext Chirp noise
Hello guys,

I have tried to use FAAD2 and FDK-AAC to decode HE-AAC with SBR extension, with FDK-AAC can play very well, but with FAAD2, sometime i got some "chirp" noise as audio file attached

Does anyone meet this problem like me, could you please share your experience about this?

FAAD2 configurations:
Code: [Select]
#define SBR_LOW_POWER
//#define FIXED_POINT
#define MAIN_DEC
#define LTP_DEC
#define LD_DEC
#define SBR_DEC
//#define PS_DEC
FAAD2 init

Code: [Select]
codec->hDecoder = NeAACDecOpen();
codec->config = NeAACDecGetCurrentConfiguration(codec->hDecoder);

codec->config->defObjectType = HE_AAC;
codec->config->outputFormat = FAAD_FMT_16BIT;
codec->config->downMatrix = 0;
codec->config->useOldADTSFormat = 0;
codec->config->dontUpSampleImplicitSBR = 1;

=> Noise has recored: IMG_0546.m4a
=> HE-AAC file: sbr-dec.aac

Thanks

Edited: I posted the wrong forum, Thanks mod to help me in the right place
  • Last Edit: 30 March, 2017, 01:12:21 AM by tuanpm

  • saratoga
  • [*][*][*][*][*]
Re: FAAD2 HE-AAC with SBR ext Chirp noise
Reply #1
Try without SBR_LOW_POWER ?

  • tuanpm
  • [*]
Re: FAAD2 HE-AAC with SBR ext Chirp noise
Reply #2
Try without SBR_LOW_POWER ?

Because I use a 240Mhz chip, it does not have sufficient decoding capability when turning off SBR_LOW_POWER

  • saratoga
  • [*][*][*][*][*]
Re: FAAD2 HE-AAC with SBR ext Chirp noise
Reply #3
I mean for testing. Disable the low power shortcuts and see if the problems are still present.

The rockbox fork of libfaad needs about 100 MHz on Arm9e without using SBR_LOW_POWER by the way. It is much better optimized then the normal code though.

  • tuanpm
  • [*]
Re: FAAD2 HE-AAC with SBR ext Chirp noise
Reply #4
Thank you @saratoga for your quick reply
When I turned off this mode, the sound seemed to be decoding very slowly. Including the FDK-AAC, I will find out why, because you can run on 100Mhz chip. Do you have any suggestions for this?

  • saratoga
  • [*][*][*][*][*]
Re: FAAD2 HE-AAC with SBR ext Chirp noise
Reply #5
We heavily optimized libfaad for ARM/Coldfire decoding:

https://git.rockbox.org/?p=rockbox.git;a=history;f=apps/codecs/libfaad;hb=a0009907de7a0107d49040d8a180f140e2eff299

The reference version is a relatively stable but requires a lot of memory and is not well optimized.