Choosing the right codec

Codecs are abundantly available on the Internet and are included in applications that let you use them to your advantage. In this section, before we get into using these codecs, let’s get one thing clear. If you are making a recording of your own song or audio track, it is best to do it uncompressed in a format such as .wav or .pcm. If you are looking to make archives of your old tapes or vinyl LP’s then you can be sure that using the above mentioned file formats will help you get the best results. But the downside is that the file size will go for a toss as saving a 4 minute audio file in the .wav format will cost you about 20MB and above in terms of disk space. As an option to this, you can use the lossless codecs that will help you save a few MB’s per file. But overall, the file size will still be larger.

Next up is the part where protecting your audio files comes in. DRM (Digital Rights Management) cannot be applied for MP3 files but it can be for Ogg Vorbis (Experimental), WMP (Windows Media Player) and AAC . Therefore, if you are making an original recording, you can use AAC or WMP to restrict your recording from being pirated.

This section will only talk about software that are freely available and we are limiting ourselves to choosing between only four codecs. These are Windows Media Audio, MP3, Ogg Vorbis and AAC. We will be using applications that let us encode a single file into any of these formats. Please refer to the workshop at the end of this chapter for the results of the test that we have performed here.

From the workshop, it is quite clear that if you can compromise on the sound quality but want lower file sizes, then you will have to stick to MP3. If you are looking for a mid-sized file with decent audio quality, then opt for Ogg or AAC. For lossless encoding, only Windows Media Audio lets you do that and as seen the file size is not much different from the original .wav file.

From our listening tests, we concluded that the AAC and Ogg files were comparable in sound quality with each other while the MP3 file did feel to be missing something. Nevertheless, if you are not a fussy listener then you can make do with any of these codecs. For the fussy ones, stick to WMA or AAC Lossless.

Newer Formats

This is the age of digital music. Since the appearance of Compact Disc or CD, music has gone digital. In a nutshell, music is stored on a CD in bits or digital numbers which is then played back on a speaker. This process involves deciphering of the digital samples to analogue sound that drives the speakers using a Digital to Analog Converter (DAC). However, similar to the CD, there is a size limitation of the Audio CD.

This is where the newer formats such as DVD-Audio and Super Audio CD (SACD) step in. DVD-Audio aims to utilize the huge amount of space that it has to increase the sampling rate and to record data in surround sound rather than in stereo. Ditto for the SACD. Let us look at what these formats have in store for us.

DVD-Audio

DVD-Audio is yet another development of the DVD Forum, the group of companies that decides what should be considered a standard in the DVD arena in the the years to come. The main advantage of DVD-Audio over the standard CD is the impressive audio quality. The table ahead will illustrate the differences between these two formats and you can make out the difference by yourselves.

Comparing DVD Audio and Compact Disc
Specification	DVD-Audio	CD
Audio Format	PCM	PCM
	4.7Gb - Single layer
Disk Capacity	8.5Gb - Dual Layer	650Mb
	17Gb - Double Sided Dual Layer
Channels	Up to 6	2 (stereo)
Frequency Response	0 - 96kHz (max)	5 - 20kHz
Dynamic Range	144db	96db
Sampling Rate - 2 channel	44.1, 88.2, 176.4KHz or 48 , 96, 192KHz	44.1kHz
Sampling Rate/Multi-channel	44.1, 88.2KHz or 48, 96KHz	n/a
Sample Size (Quantization)	12, 16, 20, or 24 bits	16 bits
Maximum Data Rate	9.6 Mbps.	1.4Mbps

The above table outlines the technical specifications for PCM on DVD-Audio and standard CD’s.

Another factor is that for compatibility with DVD-Video players, DVD-Audio discs can also contain audio encoded using the Dolby Digital and/or DTS formats. Here is the catch. Say, you have a DVD-Audio disc which contains both PCM audio tracks and the same tracks encoded in either Dolby Digital or DTS. This disc, if inserted in a DVD-Audio player will playback the PCM tracks ONLY and ignores the encoded Dolby Digital or DTS tracks. This will happen even if the DVD-Audio player supports the DVD-Video standard. On the other hand, a DVD-Video player will only play the encoded Dolby Digital or DTS tracks and ignore the PCM tracks.

DVD-Audio discs can store PCM tracks as well as associate video and images to tracks making it an all-round experience for the end-user. Another factor that makes DVD-Audio discs more favorable to the RIAA (Recording Industry Association of America) is the copy-protection part. Most DVD-Audio discs have copy protection that makes it harder if not impossible to copy music of the discs.

However, there is a downside to all of this. It is the price of DVD-Audio discs, which are pretty much on the higher side compared to a regular Audio CD. The other factor is the low penetration of DVD-Audio discs in the market since they are not compatible with the billion plus CD players around the planet. Unless, you have a player that specifies that it can play DVD-Audio, you cannot use a DVD-Audio disc.

To combat this, the DVD Forum has come out with another format called the DVDPlus or DualDisc format. This is a disc with two sides. DVDPlus/DualDisc offer either DVD-Video or DVDAudio as well as CD content so it can include video, interactivity, stills and text as well as audio. Such types of discs are also called as Hybrid Discs.