RE: [ECOS] mp3 or mpeg4 feasibility on eCos

["Robert Cragie" <rcc at jennic dot com>]

Without any knowledge of your target hardware, it's very difficult to give
'exact' roles. However, I will try to explain generally how it works.

You need to create drivers for the hardware which is doing the encoding and
decoding. These drivers will typically respond to client commands from the
higher level software (through an API, or through the operating system's
message passing service). The higher level software could be a general
purpose multimedia 'middleware' on which sit even higher level applications,
or it could be a aimpler, dedicated application, which is itself responsible
for coordinating the efforts of the hardware.

The client commands will typically program the hardware encoder/decoder via
its registers and the driver will then assume a certain state, e.g. idle,
encoding, etc. The driver then also needs to respond appropriately to the
relevant interrupts generated by the encoder/decoder in the various states
and progress the execution of the scenario which is required by the higher
level application.

So the role of eCos is to provide the infrastructure for the interrupt
handling (ISR and DSR) for all the peripherals on your target,
multi-threading to allow concurrent management of events from the various
peripherals in their respective drivers, and also to provide a
multi-threading execution environment for the application(s). One of the key
roles of a multi-tasking OS in an embedded environment is to defer
prioritisation of processing to the software environment by signalling
threads from multiple events occuring the interrupt service routine(s). In
this way, very little time is spent in the actual ISR/DSRs and there are far
fewer problems with losing interrupts, spending too much time in ISRs etc.
than with a traditional non-OS based approach.

This is really just the tip of the iceberg of a complex subject, but should
give you an idea of what it's all about.

Robert Cragie, Design Engineer
_______________________________________________________________
Jennic Ltd, Furnival Street, Sheffield, S1 4QT,  UK
http://www.jennic.com  Tel: +44 (0) 114 281 2655
_______________________________________________________________

> -----Original Message-----
> From: ecos-discuss-owner@sources.redhat.com
> [mailto:ecos-discuss-owner@sources.redhat.com]On Behalf Of Satish Kumar
> Sent: 03 October 2003 09:35
> To: Retallack, Mark (Siemens)
> Cc: ecos-discuss@sources.redhat.com
> Subject: Re: [ECOS] mp3 or mpeg4 feasibility on eCos
>
>
> well,
>       My target board contains hardware based MPEG-4 encoder and MPEG-4
> decoder and its controlled by ARM926EJ-S microprocessor..and supports
> upto 64mb memory.
>   so, whatz the exact role of software control over hardware using eCos..
> can some one give me some more inputs..?
>
> satish
>
>
> On Fri, 3 Oct 2003 09:01:12 +0100
> "Retallack, Mark (Siemens)" <mark.retallack@siemens.com> wrote:
>
> > I think the first question is what do you have?
> >
> > How much memory do you have?
> >
> > What type of processor are you running on?
> >
> > Do you have an FPU? - There are already existing libraries that can do
> > mp3/mpeg4 decompression that don't need an fpu. For example:
> >
> > 	http://www.underbit.com/products/mad/ (GPL)
> > 	http://sourceforge.net/projects/ffmpeg (LGPL)
> >
> > My first step would be to try and get ecos to compile with one
> of the above
> > libraries and a simple test application. Then when/if you find that it
> > works, decide if you want to go the third-party codec route (being very
> > careful with the licences) or create you own codec. eCos has a POSIX API
> > layer that should make porting easier(!).
> >
> > -----Original Message-----
> > From: Satish Kumar [mailto:satish@bvt.sc.sanyo.co.jp]
> > Sent: Friday 03 October 2003 08:43 AM
> > To: Retallack, Mark (Siemens)
> > Cc: ecos-discuss@sources.redhat.com
> > Subject: Re: [ECOS] mp3 or mpeg4 feasibility on eCos
> >
> >
> > so, what are the requirements if i have to develop an mpeg4/mp3 codec on
> > eCos..i know its a damn broad question to answer. but if i could get
> > some inputs , it would help me out to explore more..on this.
> >
> > right now, i just have a redboot and eCos kernel running on my target
> > board..
> >
> > thanks
> > satish
> >
> >
> >
> >
> > On Fri, 3 Oct 2003 08:34:51 +0100
> > "Retallack, Mark (Siemens)" <mark.retallack@siemens.com> wrote:
> >
> > > I see no reason why not.
> > >
> > > Have a look at:
> > >
> > > http://www.eetimes.com/story/OEG20000404S0024
> > > http://www.linuxdevices.com/news/NS6493913129.html
> > > http://news.zdnet.co.uk/business/0,39020645,2108278,00.htm
> > >
> > >
> > >
> > > -----Original Message-----
> > > From: Satish Kumar [mailto:satish@bvt.sc.sanyo.co.jp]
> > > Sent: Friday 03 October 2003 08:13 AM
> > > To: ecos-discuss@sources.redhat.com
> > > Subject: [ECOS] mp3 or mpeg4 feasibility on eCos
> > >
> > >
> > > Hi,
> > >    Can someone let me know, why mp3 or mpeg-4 kind middleware`s
> > > are difficult to develop/port on eCos. is eCos made for such
> > > applications..?
> > >   what kind of applications are usually targeted to work on eCos..?
> > >
> > > thanks,
> > > saty
> > >
> > > --
> > > Satish Kumar <satish@bvt.sc.sanyo.co.jp>
> > >
> > >
> > > --
> > > Before posting, please read the FAQ:
> http://sources.redhat.com/fom/ecos
> > > and search the list archive: http://sources.redhat.com/ml/ecos-discuss
> > >
> > >
> > > Siemens Traffic Controls is a division of Siemens plc. Registered No.
> > > 727817, England.
> > > Registered office: Siemens House, Oldbury, Bracknell,
> Berkshire, RG12 8FZ.
> >
> > >
> > > This communication contains information which is confidential and
> > > may also be privileged. It is for the exclusive use of the addressee.
> > > If you are not the addressee please note that any distribution,
> > > reproduction, copying, publication or use of this communication
> > > or the information in it is prohibited.  If you have received this
> > > communication in error, please contact us immediately and also
> > > delete the communication from your computer.
> > >
> >
> > --
> > Satish Kumar <satish@bvt.sc.sanyo.co.jp>
> >
> >
> > Siemens Traffic Controls is a division of Siemens plc. Registered No.
> > 727817, England.
> > Registered office: Siemens House, Oldbury, Bracknell,
> Berkshire, RG12 8FZ.
> >
> > This communication contains information which is confidential and
> > may also be privileged. It is for the exclusive use of the addressee.
> > If you are not the addressee please note that any distribution,
> > reproduction, copying, publication or use of this communication
> > or the information in it is prohibited.  If you have received this
> > communication in error, please contact us immediately and also
> > delete the communication from your computer.
> >
>
> --
> Satish Kumar <satish@bvt.sc.sanyo.co.jp>
>
>
> --
> Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
> and search the list archive: http://sources.redhat.com/ml/ecos-discuss
>
>


-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss