[M4IF Technotes] MEDIA streams

[Stathis Voukelatos]

Hi Kartika,
In order to use the 'mp4tool' of ENST except of your data 
stream yout need two additional files as you say (the .nhnt
and .info). If you have access to the source code of your 
video and audio encoders I think the easiest way is to 
configure you encoder to generate these files along with your
data stream. Otherwise you have to write a parser that 
parses a bitstream and generates these files.
You can find the format of the NHNT file in
http://www.comelec.enst.fr/~dufourd/mpeg-4/tools.html
Basically for each access unit (i.e. for each frame in the
case of video)the NHNT file contains a record with info like
its length, timestamp, offset from the beginning of the file etc.
The content of the INFO file (the decoder specific info as it is
called) is given by the MPEG-4 standard itself. You can find it in
the Systems part of the standard. In the case of an MPEG-4 video stream
for example, the INFO file should contain the bitstream header, that  
is the part of the stream until the first vop_start_code.
Actually, it is not as difficult as it looks to write a bitstream
parser to generate those files, because media streams contain unique
start codes that mark the access unit boundaries and so you just have 
to search for them in the bitstream.
I hope this helps,
Stathis
Stathis Voukelatos, PhD      
Software Engineer       
IndigoVision Ltd     
The Edinburgh Technopole
Bush Loan, Edinburgh
Scotland, UK
EH26 0PJ
+44 (0)131 4757345      
+44 (0)131 4757201 (Fax)  
http://www.indigovision.com
> -----Original Message-----
> From: Kartika Tulusan [mailto:kartika   artificialgods.com]
> Sent: Wednesday, March 27, 2024 10:49 AM
> To: Technotes M4IF
> Subject: [M4IF Technotes] MEDIA streams
> 
> 
> Hi,
> sorry to ask again !!!!
> I have a question regarding including audio and video streams 
> in an mpeg4
> scene.
> Does anyone know another mailing list where I could obtain 
> the information ?
> 
> Could you send me some example streams with the info files 
> etc that are
> needed
> by the V2 policy?
> I understand from below that I will need 3 files for each 
> media stream:
> >>For each raw elementary stream called stream.type, two 
> files are expected:
> >>
> >>stream.info: contains the decoder specific info, a.k.a. the headers
> >>stream.nhnt: contains the description of the access units 
> in contained in
> stream.type.
> 
> I am not sure how to create files like this. Do you have 
> anymore information
> on this
> or could you point me to some tools for parsing? (The enst site is
> mentioning some CSELT tools for
> the V1 policy)
> 
> I basically want to encode my own video and audio files and 
> use the mp4tool
> from enst to create
> mp4 files that have these streams included in the scenes.
> 
> Thanks very much.
> 
> Looking forward to hear from you soon,
> Kind Regards,
> Kartika Tulusan
> --------------------------------------------
> BSc. Multimedia Computing
> University of Westminster, London
> mobile: +44(0)79 3276 8522
> home  : +44(0)20 7377 0735
> 
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