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Topic: which kind of AAC suource code support the frame l (Read 4666 times) previous topic - next topic
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which kind of AAC suource code support the frame l

Hello everybody

You know DRM also use AAC as soure code but
I find Faac just support  frame length of 1024 samples and doesnt supprot frame length 960,
which kind of AAC suource code support the frame length 960?

Who can give me a help ?thx

sincerely

eric

which kind of AAC suource code support the frame l

Reply #2 –
thanks

The link is MPEG-4 version 1 but  the DRM system are  MPEG-4 version 2 bitstream.

I also find that for Linux compilation 2002-06-17 menno * libfaad/filtbank.c 1.10: Fixes for 960 sample transform 2002-06 ... h 1.13: * libfaad/tns.c 1.12: * libfaad/tns.h 1.4: Included decoding capability of 960 sample frame ...

but faac doesnt support 960 sample and  I  want to change FAAC to support 960 sample could you give a guide ?

sincerely


eric

which kind of AAC suource code support the frame l

Reply #3 –
Sorry, I thought that MPEG-4 V2 reference software was already public.

Hmm - you need to change scalefactor length tables,  replace all references to  window size 1024/128  to 960/120.  You also have to adapt psymodel to support this frame length, by altering initialization where tables (bark values, partitition sizes, etc..) are built.

You also need to implement 960-point MDCT - I think FAAD filterbank supports this frame size.

Also, you might need to implement reverse-order huffman coding (this is not easy)

which kind of AAC suource code support the frame l

Reply #4 –
Quote
Sorry, I thought that MPEG-4 V2 reference software was already public.

It is... Just make sure you use the code from the "rewrite" directory.

Quote
Also, you might need to implement reverse-order huffman coding (this is not easy)


Ah yes, you need to add this:
section data resilience: easy to implement
huffman codeword reordering: have fun...  (maybe this is supported in the reference code, that would make it a bit easier for you).
The reverse order scalefactor decoding is not used in DRM.

Menno

which kind of AAC suource code support the frame l

Reply #5 –
Quote
Quote
Sorry, I thought that MPEG-4 V2 reference software was already public.

It is... Just make sure you use the code from the "rewrite" directory.

Also on the FTP server of the MPEG Audio Subgroup, as far as I know...
ZZee ya, Hans-Jürgen
BLUEZZ BASTARDZZ - "That lil' ol' ZZ Top cover band from Hamburg..."
INDIGO ROCKS - "Down home rockin' blues. Tasty as strudel."

which kind of AAC suource code support the frame l

Reply #6 –
Thanks all

so i had better change ISO MPEG-4 V2 reference software to  be suitable for DRM ?
who know the forum about DRM source  coding?
and which web site (not ftp ) that  supprots the download of ISO MPEG-4 V2 reference software ?


good luck!

eric

which kind of AAC suource code support the frame l

Reply #7 –
DRM standard can be found here: http://www.etsi.org/
Source code for MPEG-4 V2 was already posted in one of the meesages by Ivan.

Menno