[Mp4-tech] Re: [Audio] Order of Syntactic elements

[Ralph Sperschneider]

Anubrata Chakrabarti wrote:
> Dear Ralph
> I have the folllowing query:
> 
> 1. Is the order of syntactic elements in the raw data block predefined? Is it 
> going to be the same as mentioned under section: 4.5.2.1.2?

The order of syntactic elements in a raw_data_block() is not predefined. It is 
howevernot recommendable to vary it unless a program_config_element() is 
available to assure the correct channel mapping.
> My concern is whether a raw data block can be decoded and passed to the 
> player (through application) as an independent unit? 

This can be done even if the order of syntactic elements in a raw_data_block() 
is not predefined.
Note: Each syntactic element comes with an element_instance_tag (except of the 
fill_element()). This allows the decoder to assure the correct relationship 
between consecutive syntactic elements in the case that there is more than one 
syntactic element of the same kind present in a raw_data_block().
> If it's true then we can safely conclude that each raw data block will have 
> exactly the same number of syntactic elements (except DSE & FIL ) as the 
> number of channels.

This can be concluded for single_channel_elements() and lfe_channel_elements(). 
channel_pair_elements() provide two channels.
The number of SCEs, CPEs, CCEs and LFEs shall be the same in each consecutive 
raw_data_block(), but the order might vary (although I know no reason why it 
actually should).
> What will be the sequence for streams having CCE? is it like
> <CCE><DSE><FIL><TERM>...

A coupling_channel_element() does never come on its own, since it will always be 
coupled on a SCE or CPE.
> 
> Thanks & Regards
> Anubrata Chakrabarti
> 

Best regards,
Ralph
-- 
Dipl.-Ing. Ralph Sperschneider  | Phone: +49 9131 776 344
Fraunhofer IIS                  | Fax:   +49 9131 776 398
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