Voice Messaging - testing compression software.

University Degree Mathematical and Computer Sciences

Voice Messaging Voice Messaging is the ability to retrieve and send voice messages from a single interface, including mobile phone, fixed network phone, or personal computer. In our case this is purely related to the Computing environment. In real practical environment, it is need for customers who need more control over communication, whether they are users who want to be in touch anytime, anywhere, or whether they are users who want more protection of privacy and/or personal time.

Compression Most types of computer files are fairly redundant. They have the same information listed over and over again. File-compression programs simply get rid of the redundancy. Instead of listing a piece of information over and over again, a file-compression program lists that information once and then refers back to it whenever it appears in the original program.

Lossless and Lossy Compression

Basically there are two types of Compression softwares.

First one is Lossless Compression. All lossless compression is based on the idea of breaking a file into a "smaller" form for transmission or storage and then putting it back together on the other end so it can be used again.

Lossy compression works very differently. These programs simply eliminate "unnecessary" bits of information, tailoring the file so that it is smaller. This type of compression is used a lot for reducing the file size of bitmap pictures, which tend to be fairly bulky. With lossy compression, you can't get the original file back after it has been compressed. You're stuck with the compression program's reinterpretation of the original. For this reason, you can't use this sort of compression for anything that needs to be reproduced exactly, including software applications, databases and presidential inauguration speeches.

Why Compression

Low Memory size acquired
Fast Data Transfer in terms of time
Less bandwidth Consumption

Why Different Compression Softwares

So how good is the system? The file-reduction ratio depends on a number of factors, including file type, file size, compression Algorithm and compression scheme.

This efficiency also depends on the specific used by the compression program. Some programs are particularly suited to picking up patterns in certain types of files, and so may compress them more succinctly. Others have dictionaries within dictionaries, which might compress efficiently for larger files but not for smaller ones.

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If a file has a lot of repeated patterns, the rate of reduction typically increases with file size. In most languages of the world, certain letters and words often appear together in the same pattern. Because of this high rate of redundancy, text files compress very well. A reduction of 50 percent or more is typical for a good-sized text file. Most programming languages are also very redundant because they use a relatively small collection of commands, which frequently go together in a set pattern. Files that include a lot of unique information, such as graphics or , cannot be compressed much with this system because they don't repeat many patterns.

Most compression programs use a variation of the LZ adaptive dictionary-based algorithm to shrink files. "LZ" refers to Lempel and Ziv, the algorithm's creators, and "dictionary" refers to the method of cataloging pieces of data.

Need for Voice Mail

Electronic mail is a common means of communication used by many organizations and individuals today and as well as being fast, it is also very effective.

With the ever increasing need for performance and output from employees, the need for voice email is felt. It is a known fact that people talk at least fifteen times faster than they type and therefore, voice email allows people to be more productive in the same span of time.

Need for Compression

The main inconvenience of using the above method is that the format in which the message is saved by various Voice Recorders is substantially large to send as an attachment. This is only suitable for messages of a short duration. When longer messages are to be attached, a problem crops up with the file size since most email applications limit the attachment size to 1 to 2 MB. Other reasons are that large attachments consume bandwidth and take longer time to upload and download. Therefore the need for compression arises.

Voice compression is a means of converting speech into data (encoding/decoding) while preserving reasonable audio quality at a low bit rate.

What follows below is a review of four voice mail applications which use different compression techniques.

1)- Voice Squeeze

Voice Squeeze was the first software that we considered as option for voice messaging system. This software is also known as Speech Compression Program because it is not good as far as compression of music is concerned. We could not check this software practically because it has license requirement of U.S $ 19.95.

Here are few characteristics related to voice Squeeze.

Low Cost Speech Compression Program
1:100 Compression Ratio
.Wav file format
Not good compression of music
Also called Speech Compression Program not Sound Compression
License required of U.S $ 19.95

Sources:

www.imagesco.com/articles/ software/VoiceCompression01.html

www.imagesco.com/articles/ software/VoiceCompression02.html

2)- Voice E-Card Version 1

Voice E-card Version 1 was second software we considered for voice messaging option. In this software you have to save the recorded message. Then you have to use E-card homepage to get the voice card service where you can send recorded message. Problem with this software is that it requires Internet connection for communication process working and also if E-card Website got down due to some reason you are stuck in the way using the voice messaging service.

Few Characteristics are shown below for this,

Start by Record Button to record voice message
Stop/Pause Button as control functionality
Save the recorded message into file
Using E-card Homepage to get sending service
Not much information about reported Metrics
License -Free

Source:

http://

3)- QUALCOMM’s Pure Voice

PureVoice is a technology developed by QUALCOMM Incorporated. It is a standard CDMA cellular technology and as well as working with cellular phones, it also works with the email system.

As compared to other common formats such as .wav and .snd for Macintosh, PureVoice technology, when used over the Internet and with Personal Computers, can reduce file sizes and the transmission times of these files by a factor of ten. PureVoice technology compresses an incoming speech signal to its most compact digital signal. This is achieved as follows:

The microphone is used to take in the digitized speech at 64 Kbps as input and this speech is then re-encoded to a lower rate digital bit stream. The voice quality is kept as closest possible to the original PCM. Because the encoding process is adjusted to the incoming speech signal, that is variable speech encoding is used, high voice quality and high compression rate are achieved.

Reported Values for Performance

As reported by the company’s website, a file with the .wav format would take up 1MB and more than 7 minutes to transmit using a 28K bps modem. Using the PureVoice technology, the same file would take up only a 100 KB and approximately 45 seconds to transmit over the same modem

Below are some characteristics and Reported metrics about Qualcomm’s Pure Voice,

File- Size: 1.39 MB
Standard CDMA Cellular Technology
Used vastly in Wireless Communication Systems
Compression Technique called ‘Pure Voice Codec’ is used
Supports Pure Voice .qcp file format (can change from .wav to .qcp)
1:10 is the Compression rate
File Transfer Peak rate: 13.3 kbps

Drawbacks

Both Sender and receiver require Qualcomm’s Pure Voice Player Recorder, because of .qcp file format for data to be sended.
Not good quality for Music that is recorded.

Source:

4)- HandyBits Version 5.5

Fourth and the final software that was considered for our voice messaging application was HandyBits. One of the important features of HandyBits is its ease of use. To record a voice message, the record button is pressed and once the message is over, the stop button is clicked. To send the message, the send button is clicked. The drag and drop option is also available whereby the recorded voice message can be directly attached to a mail editor by simply dragging and dropping into the mail editor’s window pane.

The other advantage of using this software is its compatibility with existing mail applications such as Microsoft Outlook, Eudora and Lotus Notes since it makes use of Windows MAPI. As well as its compatibility, HandyBits uses a compression technique which reduces the size of messages by up to 10 times thereby making the transmission of voices messages much faster.

The technique used, is called GSM and is the same compression technique used by cell phones. A discussion of the said compression technique is given below.

GSM

"GSM" compression uses the algorithm GSM (Global System Mobile) which is employed by telephones. GSM encoding is a very complicated process with reduces the data rate by a factor of almost five. There is little degradation of voice grade audio. The technique works as follows: Once a sound is captured using a microphone, it is filtered so as to remove lower harmonics lower than 300Hz and higher than 3000Hz. The decoding process in comparison is not as complicated and it uses only half the computational resources required for encoding. A gain-control stage then keeps the signal envelope more or less constant, before a sampling at the rate of 8000Hz, in a 13-bit format. This leads to a rate of 104 Kbits/sec, meaning that a compression algorithm is mandatory to obtain an acceptable rate of 12Kb/s.

Few Characteristics and Reported Metrics are shown below for HandyBits,

File Size: 1.49 MB
License is free for Personal Use and Business required for companies.
Use standard Windows MAPI, which makes it compatible with virtually any E-mail application
Compression Technique called ‘GSM Compression’ is used.
Supports .wav file format that is widely supported by most of sound drivers.
Addition to existing message by “Drag and Attach Window”.
Compression Ratio of 1:10
Bit-Rate is about 14kbps.

Source:

(Just used for GSM Compression)

Experimental Technique

In order to verify the performance of the software used, an experimental set up was devised.

This was done as follows:

A message lasting for 1 minute for each was chosen.
This was recorded in turn using Voice E-Card Version 1, Qualcomm’s PureVoice application and HandyBits software Version5.5.
HandyBits, one hand, uses the GSM 6.10 audio format at an audio sample rate of 8 KHz with 13 Kbps bit rate. It also uses the mono mode.
QUALCOMM’s PureVoice stores the file in PureVoice Codec format with a bit rate of 10 Kbps being used.

A table below gives a comparison of the file sizes with the each software used. Each of the files is of duration of 60 seconds.

Analysis of Suitability

With the HandyBits software, because of the fact that the resulting compressed file is saved in a

.wav format, which is widely supported, voice messages can be played virtually on any computer equipped with a sound card compared to .qcp supported by Pure Voice.
It also provides a reasonable compression ratio which is equal in Reported Metrics as to Pure Voice but less in Measured Metrics but anyhow have more Bit Rate in Kbps.
It also has good quality while compressing not only for Speech but also for Music.
We can also add into the Existing Message by “Drag & Attach Window”.

While Pure Voice have two Drawbacks that earlier mentioned in Pure Voice Section.

So our Obvious choice for Voice Messaging Application is HandyBits for reasons provided above.