[vorbis-dev] Digital Radio Monial www.drm.org

[Tor-Einar Jarnbjo]

Fredag, 11 oktober 2002, skrev du:

>Ok, here argue against this statment step by step:
>
>>Such improvements in audio coding, if obtainable, will probably 
not provide 
>>backwards compatibility with existing coding and decoding processes.
>This is why a flashable reciever is needed.

This will make the receiver too expensive. One of the DRM consortium's 
criteria for the new standard is, that a receiver should not cost 
more than 25 US$ more than a regular radio.

>>In order to allow for such a possible upgrade, it would be necessary 
to 
>>download completely new audio decoder software into the receiver. 
>DRM can transmitt data, too. So an new codec could be tranmitted one in
>5-60 Minutes to flash the receivers.

DRM seems to be using 16 or 24 kbps for audio transmissions, where 
bit-errors can be tolerated. I don't know if any bit-rates are defined 
as standard for data transmisions, but if you assume an achievable 
error-less bit-rate of 8 kbps, it will take at least one minute to 
transmit a 60 kB decoder-module. A regular radio station is probably 
not willing to make one minute breaks every now and then for transmitting 
proprietary decoder software.

>>This would preclude manufacturers from achieving the maximum economy 
of chip 
>>design and power consumption that tends to come from using a dedicated 

>>receiver chip set. 
>80% dsp power is needed for the general transmission lawer,
>20% dsp power for the audiocodec. 
>If the audiocodec is 1/3 less efficient must the dsp 7% more powerfull.

But you would need a generic DSP with a flashable ROM for the software.
If only a fixed set of codecs are in use, a specialized chip for 
this purpose can be made at a much lower cost (like it is done in 
DVD players today).

>>Also it would require foreknowledge of the processing power and 
memory that 
>>the receiver would require for any such new audio decoder. 
>How much power does a flash ROM need? 50% ?
>How much % is this form the whole system? 0.01% ?
>So this would consume 0.005% more power?

You need quite a lot of power to actually flash the ROM, and such 
an operation is generally risky with battery-operated equipment, 
as it is difficult to be sure that the available battery power is 
enough to complete the flash sequence.

>Handys are flashable, too. This feature reduce developing and >productionscost.

<p>You can upgrade some of the firmware, yes, but I know of no cellular 
phone, where it is possible to install new speech codecs. 

>As I told you, if you broadcast via DRM with MP4 you will produce 
in MP4, too.

Is there a reason why you think the broadcasters won't be using uncompressed 
PCM for production?

>So which codec will DRM-broadcaster use for internet-streaming?

WMA or Real, as most are using today?

Tor

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