AUDIO FORMATS
AULC members are discussing digital language labs
and distance learning, and are researching various audio file
formats for various purposes.
1. Plain archiving of audio material
2. Server storage for call-off by students for
lab & CALL use.
3. Distance learning via telephone dialup (web
based)
4. Autonomous learning using our Intranet (web
based)
Obviously the file formats, or at least, the data
rate will vary according to need. We also have to consider storage
space. In the past, .wav or .voc files were about our only choice.
Even then we had to balance the trade-off between file size
& quality. Now we have .wav .asf .rm .mp3 .wma etc. Each type
can vary in size according to the frequency response required
and the amount of compression used.
This page contains many different variants made
from a standard, high quality .wav file so that you can download
and evaluate.
Whilst it not suggested that AULC tries to set a common standard,
as individual institutions will have their own requirements,
it is hoped this will make comparisons easier.
There are a number of new tools available for
file creation, editing, format conversion etc.Those used for
file created here are:
Cool Edit
2000 (www.syntrillium.com) - a nice editing & processing
package that will save in most formats - .wav - .rm - .mp3 etc.
Music Match Jukebox 4 (http://www.musicmatch.com/) - this
will allow file conversion, including to.cda - .mp3 - .wma.
The data rate is selectable.
Windows Media Tools (http://www.microsoft.com/windows/windowsmedia/en/)
- These are free and allow creation/conversion to .mp3 - .wma
- .asf etc. Both the latter tools allow real-time conversion
- a great time saver. I am not recommending or inferring that
any of this software is better or worse that the others.
The file "test.wav" is a DAT recording
converted to .wav using a SB128 card.
All the compressed files below use "lossy"
compression methods and their quality must be lower thatn the
original. The question is - how much?
|
|
44.1kHz 16 bit mono uncompressed benchmark |
11.595Mb (2mins 19 sec - All files) |
| test2.wav |
44.1kHz 16 bit mono Microsoft ADPCM 3.25:1 |
3.678Mb |
| test3.wav |
44.1kHz 16 bit mono Microsoft ADPCM 3.98:1 |
3.006Mb |
| test4.wav |
44.1kHz 8 bit mono uncompressed |
5.976Mb |
|
MPEG-3 - Mono
files - will be larger in stereo
|
| mp31.mp3 |
44.1kHz 160kbs mono 4.4:1 |
2.712Mb |
| mp32.mp3 |
44.1kHz 128kbs mono 5.5:1 |
2.169Mb |
| mp33.mp3 |
44.1kHz 112kbs mono 6.3:1 |
1.898Mb |
| mp34.mp3 |
44.1kHz 64kbs mono 11:1 |
1.085Mb |
| mp35.mp3 |
32kHz 48kbs 14.7:1 |
814kb |
| mp36.mp3 |
22.05kHz 32kbs 22.1:1 |
543kb |
| mp37.mp3 |
16kHz 20kbs 33.3:1 |
340kb |
|
Microsoft ©Windows
Streaming Media - graphics and video can be added
|
| asf1.asf |
44kHz 128kbs *CD Transparency audio - stereo |
2.194Mb |
| asf2.asf |
44kHz 96kbs *CD Quality - stereo |
1.651Mb |
| asf3.asf |
44kHz 64kbs *Near CD Quality - stereo |
1.108Mb |
| asf4.asf |
22kHz 32kbs *Dialup High Quality - stereo |
555kb |
| asf5.asf |
22kHz 22kbs *Radio Quality - mono |
354kb |
| asf6.asf |
16kHz 16kHz *AM radio - mono |
286kb |
| |
* Microsoft description |
All files here are mono |
|
©RealMedia
G2 - Can be streamed
|
| rm1.rm |
22kHz 64kbs T1/LAN (High) - mono |
2.516Mb |
| rm2.rm |
11kHz 32bps - Voice - mono |
1.565Mb |
| rm3.rm |
8kHz 16bps - Voice - 28 or 56kbs modems |
842kb |
|
Microsoft ©Windows
Media Audio
|
| wma1.wma |
160kbs - Stereo |
1.647Mb |
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Quick Time
|
| qts88.mov |
8kbs 8bit uncompressed |
1.087Mb |
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Test of streaming audio
