Using to QAM to compress video/audio -- practical or not?

Hi:

Is it rational to compress video/audio -- for storing in a device with 
limited capacity or transferring on the internet via low-bandwidth 
connection -- using QAM?

Has this ever been done before? If so, what did the resulting artifacts 
look/sound like?


Thanks,

Radium

On Sep 19, 1:50 am, "Green Xenon [Radium]" <gluceg...@excite.com>
wrote:
> Hi:
>
> Is it rational to compress video/audio -- for storing in a device with
> limited capacity or transferring on the internet via low-bandwidth
> connection -- using QAM?
>
> Has this ever been done before? If so, what did the resulting artifacts
> look/sound like?
>
> Thanks,
>
> Radium

QAM is not a compression scheme. It is a modulation scheme that maps a
group of input symbols to two quadrature amplitude values. In fact,
you'll find that it does the opposite of compression; the storage for
the two I/Q coefficients will likely take much more space than the
source data. Sure, you could just store a "symbol index" value, but
then you don't get any benefit over your original data size.

Jason

Green Xenon [Radium] wrote:
> Hi:
> 
> Is it rational to compress video/audio -- for storing in a device with 
> limited capacity or transferring on the internet via low-bandwidth 
> connection -- using QAM?
> 
> Has this ever been done before? If so, what did the resulting artifacts 
> look/sound like?
> 
> 
> Thanks,
> 
> Radium

Did you mean to say Vector Quantization instead of QAM? VQ has been used 
for audio and video codecs.

John

John Sampson wrote:

> Did you mean to say Vector Quantization instead of QAM? VQ has been used 
> for audio and video codecs.

No

On Sep 18, 10:50 pm, "Green Xenon [Radium]" <gluceg...@excite.com>
> Is it rational to compress video/audio -- for storing in a device with
> limited capacity or transferring on the internet via low-bandwidth
> connection -- using QAM?
>
> Has this ever been done before?

Is it rational to XYZ for UVW using ABC?  (for a random selection
of three parameters/technologies.)  Possibly.

Especially if you don't mind sub-unity compression ratios.

On Sep 18, 10:50 pm, "Green Xenon [Radium]" <gluceg...@excite.com>
wrote:
> Hi:
>
> Is it rational to compress video/audio -- for storing in a device with
> limited capacity or transferring on the internet via low-bandwidth
> connection -- using QAM?
>
> Has this ever been done before?

I think some early digital cable transmission schemes
may have used QAM (Time-Warner's FSN over a decade ago).
Of course the video/audio data was precompressed using
an early form of MPEG to a low bit rate before, being
transport packetized and modulated back up in bandwidth
to fill one analog broadband channel.

Green Xenon [Radium] wrote:
> Hi:
> 
> Is it rational to compress video/audio -- for storing in a device with 
> limited capacity or transferring on the internet via low-bandwidth 
> connection -- using QAM?
> 
> Has this ever been done before? If so, what did the resulting artifacts 
> look/sound like?

You know many words, but few concepts. It is rational to compress milk 
with comic books?

Jerry
-- 
Engineering is the art of making what you want from things you can get.
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