Recap: Make It Small: The Magic of Audio and Video Compression
July 9, 2010 Emily Lewis
After a brief hiatus in June, Webuquerque was back in July with an excellent presentation from Jack Moffitt: Make It Small: The Magic of Audio and Video Compression. Jack talked about media compression techniques and how the human brain compensates for data loss so that quality is still perceived.
If you weren't able to join us or want to relive it all over again, here you go:
Recap
Some takeaways from Jack's presentation:
- Any time you make digital copies of light or sound, you are already using compression.
- Compression is used to make everything (the Internet, your iPod, YouTube etc.) faster.
- Lossless compression means that none of the information is lost. Also, it is "reversable."
- Lossless compression isn't great for binary stuff (images, audio) but great for text data.
- Lossy compression is great for audio-visual media that humans consume. Codecs can remove the data that humans don't perceive, so that you get smaller files without a perceived loss in quality.
- Lossy compression relies on the brain's ability to insert info that isn't actually there. We don't notice what was removed.
- Audio demo of Led Zeppelin's "Stairway to Heaven" backwards. If you hear "satan" it's your brain just trying to make sense of the words in reverse.
- How to take advantage of these brain nuances when it comes to audio compression? Get rid of hi-frequency stuff; 20 MHz and higher, which can't be perceived by most humans.
- Can also use lossy compression for images/pictures. JPEG, for example, converts RGB to YCbCr.
- There is also lossy video, which ranges from the same codecs used for JPEG to more complex codecs for MPEG-4
- Some techniques for lossy video compression: motion estimation and prediction.
- Support royalty free and open standards! Check out Google's WebM Project for one.
Slide Deck
Due to technical difficulties (thanks to Apple's ever-changing dongle requirements), we were unable to show Jack's deck during the presentation. We now have a PDF of his slides you can references:
Jack also provided the audio demos he used in his presentation:
Video
Video of the presentation is available on Vimeo:
Photos
Photos are available on Flickr:
Coming in August!
Our next presentation is An Idiot's Guide to jQuery on August 4, 2010, beginning at 6:30pm at One Up.
Local web developer and Webuquerque regular Mark Casias will explore the main features of jQuery and jQuery UI.
Registration for our August event is not yet open, but be sure to mark your calendar! We'll be opening registration up about two weeks prior to the presentation and will notify our members across our various social networks, as well as on this site.
Don't Miss Future Events!
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You can also add our schedule to your Google Calendar. Or download to your address book.
Seeking Volunteers
The ongoing success of Webuquerque has been a wonderful surprise to both Jason and I. It also means, though, a greater need for time and energy on our parts. We'd really like to get some help from our community to allow this group to keep going.
There are some specific tasks we could use volunteers for. Please take a look and let us know if you'd like to lend a hand.
Let Us Know What You Think
As always, we want to know what's on your mind so we can do the best to ensure Webuquerque is all you want it to be. Make sure to let us know if you have any suggestions, comments or complaints.
See you on August 4!