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

Started by Green Xenon [Radium] September 19, 2007
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. &macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;&macr;