[opendtv] Re: Pros/Cons of DSP processor based MPEG software decoder or hardware based MPEG decoder
- From: "Donald Koeleman" <donald.koeleman@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Tue, 8 Feb 2005 23:14:48 +0100
----- Original Message -----
From: "Tom McMahon" <TLM@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Tuesday, February 08, 2005 9:15 PM
Subject: [opendtv] Re: Pros/Cons of DSP processor based MPEG software
decoder or hardware based MPEG decoder
A couple of points:
1) There are now a number of hardware H.264/AVC chips and also a number of
licensable H.264/AVC hardware (Verilog/VHDL) cores. I
can send you a list if you're interested in that level of detail.
2) H.264/AV was developed jointly by MPEG (ISO) and VCEG (ITU) in a
cooperative embodiment known at the JVT (Joint Video Team). So
MPEG versus MS isn't quite an accurate characterization. Also, MS is very
much an H.264/AVC patent holder as well, so saying MS
versus any of the above doesn't quite work. Weird situation this one.
Two groups of products, Windows Media 9 and derivatives, and ISO MPEG 4
AVC/ITU H.264.
3) My sources tell me that once a video decoder design is implemented,
debugged, and optimized for hardware, it occupies such a
small piece of real estate on typical STB chips that it is easy to put more
than one such decoder on the chip. They also suggest
that this notion of recycling certain math/function blocks across two
different decoders doesn't work out very well. Even codecs
which have some degree of similarity at some level (H.264/AVC and VC-1 some
would say) are very very different at the hardware
implementation level.
Indeed, the problem would propably not lie with footprint, but with
processing and memory demands.
In case of multiple codecs, licensing may indeed bcome a cost factor.
4) The notion of dynamically swappable SW video decoders may work on PCs but
it won't work very well in STBs and DTV sets. The
possibility of doing a channel change between, say, H.264/AVC and VC-1 and
not having a long burp in the video is remote without a
lot of very careful systems work (which hasn't been done yet by any
standards body).
Don't think some-one is actually proposing to do so. The programmable chips
are only designed to allow for upgrading to better codecs, not to be used
for switching between multiple codecs on a continuous basis.
5) As far as I know, the following have announced decisions to go with
H.264/AVC: DIRECTV, Echostar, DVB mandated for HDTV
applications, DVB optional for SDTV, Euro1080, French DTV (or some subset),
Japan for mobile.
Let's not forget Premiere wich has announced a November 1 launch of its
three channel HD bouquet.
French DVB-T only for the HD channels and new services (mandated), the
regular channels are still to start broadcasting in MPEG 2 MP@ML this
spring. The mandated use of H.264 met with resistence from the broadcasters,
so TF1 made a jump forward and proposed to use H.264 for the regular
broadcasts from the start.
Donald
-----Original Message-----
From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On
Behalf Of Donald Koeleman
Sent: Tuesday, February 08, 2005 5:35 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Pros/Cons of DSP processor based MPEG software
decoder or hardware based MPEG decoder
MPEG 2 MP@ML decoder chips are generaly all hardware, the technology on
these chips has matured over the past decade and there is no
real need to update the decoding capabilities after the box leaves the
factory. MPEG 4 Main profile standard definition decoders are
available in hardware, however anything newer or higher spec, like H.264 or
WM9/VC1 uses software codecs.
Several reasons, largely to do with economies of scale, as numbers are still
relatively small. Codecs are still under development,
so generations of capability sets replace eachother quite rapidly, so no
time to design and build a hardware implementation and
recoup cost. The market is still split between MPEG and Microsoft, and large
operators are still making up their minds as wich
platform to choose and current service providers do not want to be locked in
right at the start of the development of this
technology.
Donald
----- Original Message -----
From: "Prashant Desai" <prashant.desai@xxxxxxxxxx>
To: <opendtv@xxxxxxxxxxxxx>
Sent: Tuesday, February 08, 2005 12:25 PM
Subject: [opendtv] Pros/Cons of DSP processor based MPEG software decoder or
hardware based MPEG decoder
Hello All
i am new to this digital content would , i would like to know and
understand the Pros/Cons of different methods of implementation of the
MPEG -4 , MPEG-2 decoder is better compared to the other .
Based on my current understanding there are two ways by which the MPEG-4
/MPEG-2 decoder's can be implemented the first method is using a combo of
DSP processor and software implementation of MPEG-4/2 decoder whereas the
other is to implement the full hardware based MPEG-4/2 decoder , i think
it's always better to have 100% hardware based
decoder from performance point of view , i dont know what are the advantages
of using a software based MPEG-4/2 decoder on the top of DSP processor
..........
i would be really grateful if you guys can provide your opinions and imputs
in this regard
warm regards,
Prashant Desai
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