Saturday, November 21, 2009

An FCC workshop on Future Fiber Architectures and Local Deployment Choices. It looks like the FCC gets it.

The FCC just held a Workshop on Future Fiber Architectures and Local Deployment Choices.

The workshop was comprised of two panel sessions featuring a mix of academic, industry, market research and community networking people. Video of the panels and the panelist's presentation slides are available at the workshop Web site.

The range of speakers and their presentations leaves me optimistic that the FCC “gets it” – they are listening to good people with diverse views and no longer define "broadband" as 250 kbps.

I have summarized the workshop by selecting one slide from each presentation and adding a short comment to each. I have not listened to the presentations – the comments are what occurred to me when I selected the slide.

Selecting the slides to include was difficult – I left out some good ones, and would recommend your looking at the rest and listening to the presentations if you are interested in broadband policy.

This is an experiment in how to cover and summarize a conference.

For another excellent summary see this post by Goeff Daily in which he extracts noteworthy quotes from the presentations.

Friday, November 20, 2009

Can you hear the difference when audio is compressed?

We have seen that images can often be compressed significantly without noticeable degradation.

A recent review asks whether one can distinguish between a file that is ripped from a CD with no loss and a compressed MP3 version of the same file.

There were only seven subjects in this small test. They were given two recordings of two rock songs and asked to tell which sounded best. One was a lossless recording ripped from a CD, the other the same file compressed. Some compared the lossless files to 192 kbps MP3s, others compared them to 320 kbps MP3s. (Apple iTunes music is 128 kbps).

Only one person could accurately pinpoint which tracks were MP3 in every case. Of the rest, three subjects picked the lossless track twice and the other three only made one correct choice.

This is obviously a limited test -- there were few subjects and few controls. The results might be affected by things like

  • the quality of the playback equipment
  • the hearing acuity of the subjects
  • the familiarity of the music to the subjects
  • the nature of the particular song or other audio
Still, a test like this makes one wonder whether bandwidth is wasted by a lossless file.

You could easily create a similar test and try it on your friends (and yourself).

It would also be interesting to do a test of recorded voice. Podcasts are typically delivered as 64 or 128 kbps MP3 files -- can listeners tell the difference? Would a higher data rate matter?

As storage cost falls and bandwidth increases, how is the audio compression tradeoff of file size versus quality affected?

Thursday, November 19, 2009

An example of bad image processing on the Web

We discuss the importance of processing, resizing and compressing an image before uploading it to a Web site.

This image, found on the WiFi Alliance Web site, provides an excellent example of what not to do:

As we see in the property sheet, the image is 980 by 664 pixels and the file size is 1.28 megabytes:

Resizing and compressing the image before putting it on the Web site would have reduced it to about 5
kilobytes -- 1/250th the size of the original -- with no noticeable loss of quality. (Quality is not even important in this case since the image is just a button linked to a video).

Furthermore, the image is resized to 177 by 99 pixels, which distorts it by changing its aspect ratio. (It appears that the image was also distorted when it was captured).

We can learn from our and other's mistakes -- can you find other poorly processed images on the Web?