Increasing MP3 encoding quality
- 17 July, 2002 10:44
It's not uncommon for even the most casual listener of MP3s to be distracted from the music to which they are listening by an apparent loss in sound quality, either overall or at some stage throughout a song. One way to increase MP3 sound quality is to encode MP3s at a higher bit rate than the near-CD sounding 128Kbps (Kilobits per second) - such as 160Kbps, 192Kbps or even 320Kbps, although some may argue that the increased bit rate only benefits a well trained ear. The downside is that the higher the quality at which an MP3 is encoded, the larger its file size will become. For anyone with limited storage capacity on a personal MP3 player or limited hard disk space on a PC, a compromise between sound quality and file size is required.
This assumes that a user is encoding MP3s using the most common compression method, called Constant Bit Rate (CBR). A new type of encoding method termed Variable Bit Rate (VBR) has emerged that is ideal for users facing this situation, as well as audiophiles who want to maximise the sound quality of MP3s.
CBR - the more common encoding method, which is usually the default - maintains a consistent bit rate throughout the encoding of an MP3, which gives predictable MP3 file sizes. However, if the music selected for encoding is complex in structure, an additional loss of quality may occur; this is because, in order to satisfactorily capture the complex music parts, more bits are required, yet the music is only encoded at the consistent pre-selected Constant Bit Rate. This means that in music with many fluctuations, the less complex music section will be encoded using more bits than required, whereas complex sections will not use enough bits to adequately encode it. As mentioned, the only way to avoid this is by encoding at a higher CBR, such as 160Kbps.
In contrast, the Variable Bit Rate encoding method allows for consistently high quality throughout an MP3 by increasing the bit rate for more dynamic and complex parts of the selected music as required. Subsequently, it reduces the number of bits encoded as needed, such as during a quiet or silent portion.
One disadvantage of VBR encoding is that even though the bit rate range is set before encoding begins, the output MP3 file size can't be predicted adequately. Additionally, many personal MP3 players currently don't support VBR, although Apples' iPod with its VBR support is leading the market.
In the Essentials section of this month's first cover CD, you'll find the latest free version of MusicMatch Jukebox - an all-in-one tool that will rip a CD using the Variable Bit Rate encoding method.
Using VBR encoding
When you launch MusicMatch for the first time, a few windows may open. If the CD Lookup window opens, simply click Cancel; click Close if the Tip of the day window appears. This article will guide you through the process of ripping, so you can also close the large Getting Started window by clicking on the white square at the top right.
Once you're ready, go to the Options menu, select Settings then click the Recorder tab. Clicking the Track Directory button will allow you to choose the output directory and which track information - such as artist, album and song name - will be attributed to the MP3 file. Click Cancel when you have finished.
Tick the Add to Playlist box so that after the track has been ripped it will be added to MusicMatch's song play list.
Under the Custom Quality section, select MP3 VBR. You'll notice a slider that goes from 1 to 100 that allows you to customise your VBR rip. The lower the number, the lower the quality and the higher the compression, while a higher number means higher quality and lower compression. As a rough guide, MusicMatch states that a setting of 50 sets a base encoding bit rate of 128Kbps, while 75 is approximately 160Kbps.
Click the red (Record) MusicMatch control button and place your audio CD into the drive. If you're connected to the Internet, the CD's album and track information should be found for you automatically, but if not, you can click Refresh and enter the information manually in the CD Lookup window.
Place a tick next to each track you want to rip and commence ripping by clicking the Start button. The bottom of the recorder window has a progress indicator. When each track has finished ripping, it will be added to your music library and play list.
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