Simple Audio Compression Methods

Traditional lossless compression methods (Huffman, LZW, etc.) usually don't work well on audio compression (the same reason as in image compression).

The following are some of the Lossy methods applied to audio compression:

• Silence Compression - detect the "silence", similar to run-length coding
• Adaptive Differential Pulse Code Modulation (ADPCM)
  e.g., in CCITT G.721 - 16 or 32 Kbits/sec.
  (a) encodes the difference between two consecutive signals,
  (b) adapts at quantization so fewer bits are used when the value is smaller.
  • It is necessary to predict where the waveform is headed -> difficult
  • Apple has proprietary scheme called ACE/MACE. Lossy scheme that tries to predict where wave will go in next sample. About 2:1 compression.
• Linear Predictive Coding (LPC) fits signal to speech model and then transmits parameters of model. Sounds like a computer talking, 2.4 kbits/sec.
• Code Excited Linear Predictor (CELP) does LPC, but also transmits error term - audio conferencing quality at 4.8 kbits/sec.

Nokia allies Microsoft to avoid oblivion

Embattled Nokia has entered a wide-ranging alliance with Microsoft in a last ditch bid to repel an onslaught from Apple and Google.
In a screeching U-turn, the world's largest handset maker will all but abandon its own underwhelming mobile phone software and use Microsoft's operating system instead.
But the Finnish giant lost a tenth of its value after the far-reaching deal came to light amid concerns that Nokia was giving too much away to its new American partner.
The pact is the most dramatic move yet in an attempt to revive the struggling Nokia by new boss Stephen Elop, who defected from Microsoft in the autumn.
It follows four years of abject humiliation for Nokia since the launch of the iPhone, which has seen Apple snatch the Finnish group's crown as the kingpin of mobile phones.
At the same time, Nokia has been losing out in the mid-tier of the mobile phone market to handsets built using Google's Android platform. And its supremacy in cheap phones is also under threat from low-cost Chinese rivals.
In a sensational email to staff leaked onto the internet this week, Elop likened Nokia's predicament to an oil rigger on a 'burning platform' forced to hurl himself into the icy waters.
The hard-hitting memo claimed Nokia had fallen 'years behind' rivals and risked hurtling into oblivion unless a 'huge effort' was made to transform Nokia.
Yesterday, Elop claimed that it was now a 'three-horse' race in the booming market for smartphones, which are now outselling PCs.
But analysts are sceptical. Unlike Nokia and Microsoft, Google and Apple have developed slick and user-friendly systems, spawning millions of software applications.
Geoff Blaber of technology research group CCS Insight said: 'This is a partnership born out of both parties' fears of marginalisation at the hands of Apple and Google.

Google, Facebook Users Fret Over Privacy and Viruses

Many Facebook and Google users have a general sense of unease when online, with concerns about privacy and viruses, but experts caution that we don't understand who's getting access to our data and for what purpose. The erosion of security and privacy go hand in hand, as it becomes easy to create accounts and do most activities on the web.

Most Americans are worried about privacy and viruses when using Facebook or Google, according to results of a USA TODAY/Gallup Poll released Tuesday.Nearly seven out of 10 Facebook members surveyed -- and 52 percent of Google users -- say they are either "somewhat" or "very concerned" about their privacy while using the world's most popular social network and dominant search engine.
Even so, technologists and privacy experts say most people lack a clear grasp of the complex risks they accept whenever they're on the Internet. "Consumers generally do not understand who's getting access to their data and for what purpose," says Ryan Calo, director of the Consumer Privacy Project at the Stanford University Center for Internet and Society.
Many of us "have a general sense of unease" when we're online, Calo says.
The poll found that a similar percentage of Facebook and Google users -- 65 percent and 54 percent, respectively -- say they are worried about Internet viruses.
"In my mind, that shows a lower level of concern (about viruses) than folks really ought to have," says Lisa Sotto, head of privacy and information management at law firm Hunton & Williams. "There is probably a lack of understanding about how very dangerous viruses can be."
The erosion of security and privacy often go hand in hand. Social networks, banks, tech companies and retailers continue to make it easier than ever to create accounts, share personal details and do most activities on the Web.
This is being driven largely by advertisers' desire to make online pitches to the person most likely to buy. "The only way that happens is through the collection of huge amounts of data about each of us, followed by the sale of the data," says Michael Fertik, CEO of identity management firm Reputation.com.
Data flowing through the Web have translated into a candy store for criminals. It's easier than ever for even low-skilled hackers to spread infections via e-mail , Facebook and Twitter postings and corrupted Google search results. Risks are rising with the use of smartphones, tablet PCs and e-readers to access the Web.
Some companies are doing what they can. "I'm heartened by the attention to mobile privacy issues," says privacy attorney Chris Wolf of Hogan Lovells. New services revolve around "ways to empower people to protect their information."