[Mp4-tech] Re: how to play .aac fille with adif header

[Ralph Sperschneider]

rgomathi sarayusoftech.com wrote:
>> Hi Apoorva.....
>>     
>     Thanks for your reply.....
>     Actually I'm working in Mp4 file format.In the mpeg systems doc....in
> object type indication it is given that for 0x6b,0x69 the stream
> comply to mpeg1 audio and mpeg2 audio.....So once i got that info i
> came to know that the audio stream is mpeg1 or mpeg2 audio and i'll
> parse the stream as such without any decoderSpecificInfo as the
> mpeg1,mpeg2 (layers I,II,III) audio streams itself contains all the
> info needed for decoder.
>     I do see streams (.mp4 file) with .mp3(inside the moov atom) and 
> there is no esds atom....so how to parse this stream..... is there any
> more codec like this....please guide me experts .....
>
> Thanks in advance
> Regards,
> Gomathi.
>
>   
Dear Gomathi,
I am unsure about your current topic. You started to ask for players 
supporting ADIF, later you disclosed that you are interested in decoding 
content stored in the mp4 file format, and here you refer to Layer-1,-2 
and -3. Assuming that you are interested in decoding MPEG-2 AAC content 
stored in an mp4 file, please note that the correct objectTypeIndication 
is, depending on the profile:
0x66 Audio ISO/IEC 13818-7 Main Profile
0x67 Audio ISO/IEC 13818-7 LowComplexity Profile
0x68 Audio ISO/IEC 13818-7 Scaleable Sampling Rate Profile
Note further, that in ISO/IEC 4496-1, subclause "2.6.7.2 Semantics", the 
following is stated:
"For values of DecoderConfigDescriptor.objectTypeIndication that refer 
to streams complying with ISO/IEC
13818-7 the decoder specific information consists of the ADIF -header if 
it is present (or none if it is not present) and an access unit is a 
„raw_data_block()“ as defined in ISO/IEC 13818-7."
Hope this helps,
Ralph
>
>  Hello Gomathi,
>   
>> AAC bit stream according to the standard, contains only syntactic
>> elements (SCE, CPE, LFE, DSE, PCE, FILL, CCE, TERM). So if an AAC
>> decoder is developed, it will be implemented to support and decode the
>> syntactic elements compulsorily. Let us call the AAC containing only
>> syntactic elements as "Raw AAC".
>>
>> When we consider ADTS or ADIF, these are headers which provide
>> information about the bit stream like sampling rate, channels, etc. And
>> these headers (ADTS, ADIF) are not the only format, AAC bit stream could
>> be encapsulated in. Raw AAC can even be a part of MP4 transport stream,
>> in which the data like Sampling rate and channels will be a part of
>> configuration information.
>>
>> So, if a player has AAC decoder but, do not have the implementation to
>> decode the headers (ADTS, ADIF) then, the player can very well decode
>> the "Raw AAC" (information of Sampling rate will have to be provided by
>> the user) but, will not be in a position to decode the AAC with ADTS or
>> ADIF header.
>>
>> Hope this helps,
>> Apoorva Ankad
>>
>> -----Original Message-----
>> From: rgomathi sarayusoftech.com [mailto:rgomathi sarayusoftech.com]
>> Sent: Wednesday, November 22, 2023 2:37 PM
>> To: Deshpande, Vishvanath; mp4-tech lists.mpegif.org;
>> mp4-tech-request lists.mpegif.org
>> Subject: Re: [Mp4-tech] how to play .aac fille with adif header
>>
>>     
>> Hi all....
>>    Thanks a lot for ur replies.can i know the reason behind why only
>> certain players  could play the .acc with ADIF header.B'coz both ADIF
>> and ADTS headers can be used to create .aac file in general.I think the
>> only difference being one time ADIF header for the whole stream and
>> ADTS for every frame.If i'm correct why the normal players couldn't
>> play that.is there any special thing the decoder should do to decode
>> aac stream with adif.....expecting replies...
>>
>> Thanks in advance,
>>
>> regards,
>> Gomathi.
>>
>>
>> Hi,
>>     
>>> You can use Cool Edit to play that,
>>>
>>> -Vishvanath
>>>
>>>
>>>
>>> ----- Original Message ----
>>> From: "rgomathi sarayusoftech.com" <rgomathi sarayusoftech.com>
>>> To: mp4-tech lists.mpegif.org; mp4-tech-request lists.mpegif.org
>>> Sent: Tuesday, 21 November, 2006 3:58:41 PM
>>> Subject: [Mp4-tech] how to play .aac fille with adif header
>>>
>>>
>>> Hi all......
>>>    I badly want to know how to play .aac file with adif header.for the
>>> same raw data with adts header most of the players like vlc,quick time
>>> players play exactly well.but if i put adif header for the same even
>>> VLC 8.5 doen't play.would i do somthing special to play this in
>>> vlc....please guide me experts...expecting replies asap...
>>>
>>> Thanks in advance
>>> Gomathi
>>>       

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