Information Technology Reference
In-Depth Information
when trying to squeeze a few extra bytes out of an image. The same method of
removing parts of a digital image to decrease the size, while not compromising the
integrity of the image, can also be applied to audio.
In the example of MP3, a compression algorithm is run through the digital audio and
removes parts of the track that normally the average human ear is not able to pick up. A
lower bitrate for the MP3 file indicates that more data have been removed from the
recording.
While some individuals claim to hear a tinny sound from MP3s due to the missing audio
information, most people cannot seem to tell the difference when compared to a
lossless digital copy. This makes MP3 a fantastic audio codec to use for your HTML5
audio as you can get incredibly small files that download and stream quickly to your
user's browser. This being said, you should be careful to use a decent bitrate for an
MP3 file—say 128 kbps. Anything lower may have a tinny sound on quality audio
devices (for example, the HTC Rezound). Moving up to 192, 256, or 320 kbps may be
useful if it doesn't make the file too big; however, you may find it unnecessary given the
relatively small benefits. Over 320 kbps is probably a waste unless your app is built for
audiophiles!
For the most part, MP3 is the de facto audio format of the Internet, which is why almost
every major browser supports MP3 audio with HTML5 out of the box with no additional
plug-ins.
AAC
Advanced Audio Coding, also known as AAC, is another audio format out there on the
horizon. If you have ever purchased music off of Apple iTunes, then you have most likely
purchased music in this audio format. AAC was developed by several companies—
including Sony, Nokia, Dolby, and AT&T. This format, which does achieve better audio
quality than its MP3 predecessor, was declared an International audio standard in the
spring of 1997.
One of the reasons this audio format is popular with developers, besides the obvious
fact of having better sounding audio compared to its competitors, is that no licenses or
patent payments are needed to distribute or stream AAC encoded content. Note that
this licensing only applies to the actual encoding—you can't take copyrighted material
that doesn't belong to you, encode it in AAC, and laugh at the lawyers after you
distribute it to the world. Well, I guess you can laugh, but that's not going to help your
case!
Ogg
Another up and comer in our quest to conquer HTML5 audio on Android devices is one
of my personal favorite codecs: Ogg. The creators of Ogg have stated in the past that
they created Ogg to be a format that was not bogged down by restrictions and software
patents. This has promoted Ogg's adoption as a default HTML5 audio codec in a
majority of browsers out there. There is a good chance that if you encode your audio in
