[M4IF Technotes] MPEG4 subsampling

[Wouter Favoreel]

Hi Renaud,
Thanks for your quick response.
You are of course right with the 7.5 I frames but 7 or even 5 is ok as well.
Our point is that we just want a low bandwith stream (not necessarily MPEG4)
from a high bandwidth MPEG4 stream.
Any idea what a sequence of only I-frames looks like?
Can they be extracted (easily) an MPEG4 stream?
Regards,
Wouter
-----Original Message-----
From: Renaud Cazoulat [mailto:renaud   envivio.com]
Sent: dinsdag 21 januari 2003 16:25
To: Wouter Favoreel
Cc: 'technotes   lists.m4if.org'
Subject: Re: [M4IF Technotes] MPEG4 subsampling
Hi
I guess that the I frame interval is an important variable to take in
account
;-)
You example will work only if the high badwidth video has an Iframe interval
of
7.5
This value is not yet adopted world wide.
Furthermore, by taking only the I frames you will loose the P (and maybe B)
frames benefit.
I would say that the best solution is to decode/re-encode.
renaud
Wouter Favoreel wrote:
> Dear,
>
> Is there anyone who knows how to extract a low bandwith compressed video
> stream (e.g. CIF @ 4 fps @ 0.4 Mbps) from a higher bandwith elementary
MPEG4
> stream (CIF @ 30 fps @ 2Mbps) ?
>
> We thought of only taking the intraframes ? Maybe there is another
solution?
>
> Thanks for your time,
>
> Wouter Favoreel
>
> Tel. + 32 56 36 17 25
> Fax. + 32 56 36 21 96
>
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