ITEC2110:Fall2010:PodcastProject:FThompso

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Wayne Thompson's Podcast (Audacity) Project

Using 28.8Kbps for dialup downloading speed and 1.5Mbps for DSL downloading speed.

Uncompressed vs. Compressed

Format

File size

Download time (Dialup)

Download time(DSL)

Link to Download

Using Audacity I produced a .wav format file which is:

41.8 MB

3 Hours 22 Min 31 Sec

3 Min 42 Sec

Click here to download this version

Using Audocity I produced a .mp3 format file which is:

3.8 MB

17 Min 35 Sec

12 Sec

Click here to download this version


Quantization and Sampling Rates

CD quality audios are usually sampled at 44,100 samples per second with a 2 byte quantization level.

Format

File size

Dialup download time

ADSL download time

Download

Using Audacity I produced a .wav format file which has a sample rate of 44100 samples per second and a quantization level of 32 bits:

5.89 MB

27 Min 16 Sec

18 Sec

Click here to download this version

Using Audacity I produced a .wav format file which has a sample rate of 44100 samples per second and a quantization level of 16 bits:

5.89 MB

27 Min 16 Sec

18 Sec

Click here to download this version

Using Audacity I produced a .wav format file which has a sample rate of 8000 samples per second and a quantization level of 16 bits:

1.06 MB

4 Min 54 Sec

3 Sec

Click here to download this version



Reflection Questions

  • What's the difference between WAV format and MP3 format and how different formats affect downloading time? (Hint: file size; compression)(Read the wiki page for more information)
Answer: The main difference is that WAV files are uncompressed and MP3 files are compressed. The amount of compression MP3 formats apply can vary.
  • Do you know any other audio format? Please list at least one.
Answer: Ogg is another audio file format. It is comparable to MP3 files in terms of sound quality and is open source.
  • How sampling and quantization affect audio quality?
Answer: Sampling creates values at discreet intervals along an analog wave while quantization restricts these discrete intervals to fixed values based on a preset scale. Audio quality is based on how high or low the sampling rate is. Low sampling rates result in a loss of accuracy/file information thereby generating poor sound quality. Insufficient quantization leads to a lose of definition.



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