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Appeared on: Tuesday, May 24, 2005
How to convert your music


1. Introduction

Nowadays, a blank DVD-ROM disk costs about €0.40 and a blank CD-ROM disk about €0.20. So why stick with audio CDs and have about 20 tracks on each disk when you could convert your audio tracks to mp3 and have about 175 on each CD or even better, use a DVD and have around 1125 tracks? In this tutorial, we will discuss ways to convert your audio tracks to this highly compressed format by using freeware programs.

Programs that you will need. Click to go to the homepage of each program and to download it.

CD-Ex
Aspi Drivers (Only if you want to use CD-Ex)
dBpowerAMP Music Converter (dMC)

Installation:
Before the writing of this review, dBPowerAMP Music Converter was a totally freeware program. Unfortunately, during the course of writing this review, dMC switched the mp3 encoder to a 30 day trial license. Other than this, the program is 100% free. However, because of the trial license restriction, we will use CD-Ex for the purposes of this review.

CD-Ex: Installing CD-Ex is really simple and straightforward so there's no need to discuss it here. What CD-Ex does need however, is the ASPI Drivers installed in order to run properly. We used the Nero ASPI Drivers (which also recognizes USB connected drives). Download the wnaspi32.dll and copy it to the "%WINDOWS_DIRECTORY%\System32" folder (for example C:\WINDOWS\system32) or to your application directory (no need to reboot).

dBpowerAMP Music Converter (dMC): The installation procedure is also very simple and it only takes a few seconds.

The next step is to look through all the available formats and to determine the format we need.


2. Audio Format Explenations

There are a lot of audio formats that are available but which of them is the best? The answer depends on your needs. Initially, we can categorize them into 2 basic types of audio format, lossless and lossy formats. Read carefully through the format descriptions below to find the one best suited to your needs.

Lossless formats: With a lossless format, you will have the highest fidelity (based on the original source of course). Typical examples are Audio CD tracks. You can use this format if you don't care about the final size of your audio files (it can be about 40 MB for a 4 minute audio track) and you will need to use your your PC to listen to these because lossless formats are not usually supported by portable devices such as mp3 players.

Lossy formats: The most popular formats are the lossy formats, such as mp3 and wma. When we convert an audio file into a lossy format, we want higher fidelity with audio that we need to hear most clearly (such as music) and we can be more tolerant with audio where we are less likely to notice any difference (speech). Lossy compression techniques can compress the audio file more than 10 fold without having any noticeable loss in fidelity.

Lossless formats

Monkeys Audio (APE): Monkeys Audio is a lossless audio compression codec. Unlike lossy codecs such as MP3, Ogg Vorbis, or Advanced Audio Coding that permanently discard quality to save space, Monkeys Audio compresses audio in a mathematically perfect way, creating bit-for-bit copies. Therefore, a file compressed with Monkey's Audio always sounds the same as the source file, no matter how many times the resulting file is burnt to a CD, ripped and re-encoded. The best compression ratio that can be obtained is 4:1.

Free Lossless Audio Codec (FLAC): FLAC is a free and open-source codec that is similar to MP3, but lossless. Unlike lossy codecs such as MP3 and Ogg Vorbis, FLAC does not remove any information from the audio stream. It will only obtain a maximum of 4:1 compression but usually 2:1 for normal use so a 4 minute track will take up about 20 MB. Although it is similar to Monkeys Audio, it loses slightly in the compression ratio compared to Monekys audio as well as in speed.

Lossy formats

Advanced Audio Coding (AAC): Also called MPEG-4 AAC, this audio codec is the continuation from the MP3 codec created by Fraunhofer-Gesellschaft. Due to advances in the technology, AAC files encoded at a 96 kbps bit rate, sound slightly better than MP3s encoded at 128 kbps.

MPEG Layer 3 (MP3): Although it's compression routines are not the best, mp3 has become the most widespread standard for audio compression. It is capable of 10:1 compression with no noticeable loss in quality. MP3s have become a popular way to distribute CD quality music on the Internet. By using this format of compression, a normal audio track is compressed to around 3 - 4MB in size. Nowadays, every portable audio device, media player and standalone DVD player supports this format.

MPEG-4 Part 14 (MP4): This is a file format specified as part of the ISO/IEC MPEG-4 international standard. It is used to store media types defined by the ISO/IEC Moving Picture Experts Group and can be used to store other media types as well. It is, or will be, typically used to store data in files, though it will be used in data streams and possibly in other ways. MP4 can contain both audio and video files and the main audio format is Advanced Audio Compression (AAC).

Windows Media Audio (WMA): Window's Media Audio is Microsoft's audio encoding format that is starting to gain popularity due to its high quality output at lower file sizes. A 96 kbps (and in some tests a 64 kbps) wma file is equivalent in sound quality to a 128 kbps MP3 file. It is strongly recommended for uses where there is limited memory capacity. It is the most popular format after mp3.

Ogg Vorbis (OGG): Ogg Vorbis is an free and open-source digital audio compression format like MP3. Just like mp3, it offers variable-bitrate encoding options, for better efficiency. The algorithms Ogg Vorbis uses to decide which information to discard, differs from those used by MP3. As a result, Ogg Vorbis produces files that are significantly smaller than MP3s with similar sound quality. It is becoming more and more popular and a lot of standalone players are starting to support it. (Like i-river flash, CD players and Rio Karma).


3. Encoding Settings

Concentrating a little on lossy encoding formats, there are some options that we must consider before we continue to encode our audio files.

1) Bitrate:
The bitrate is usually measured in 1000 bits per second or Kbps compression. The higher the bit rate, the higher the sound quality we will have but also, the larger the size of the resulting compressed audio file. Note that it is pointless to convert an audio file from a lower bitrate to a higher one higher (for example to convert a file from 128Kbps into a file of 256Kbps). The output file will still have the quality of the first file, i.e. 128kbps.

2) Lossy encoding options:
We have the following options when we are converting an audio stream to a lossy format:
Constant Bitrate (CBR): With this option, the same bit rate will be used to encode the entire audio file.
Variable Bitrate (VBR): VBR specifies the sound quality level but allows the bit rate to fluctuate. During complex passages, VBR uses a higher-than-average bit rate but during simple passages uses a lower-than-average bit rate. The result is that VBR produces an overall higher, more consistent sound quality compared to CBR at similar bit rates.
Average Bitrate (ABR): This is similar to VBR except that ABR is an encoding method that maintains the same bitrate across the entire audio file by regulating how variable the compression is.

3) Channel Selection:
Stereo:
Two channels of audio, one for the left, and one for the right This is used to give the impression of space and movement.
Mono: One channel only. If you convert an audio stream with two channels into an audio stream with only one channel, both audio channels will be mixed together into a single track, using equal amounts from audio channels 1 and 2.
Joint Stereo: Joint stereo is the technique of encoding stereo audio into a "mid channel" which is a full channel average of the combined left and right channels, with a side channel which has separation information on how to re-create two distinct stereo signals. This can aid the compression ratio without having to lose valuable information from one of the audio channels.

4) Frequency:
Rate of measurement of samples per second. The higher the value, the better the sound quality will be. For example a CD stores samples at 44100Hz or 44.1KHz and a DAT tape stores samples at 48KHz.

5) Normalization:
When we use the normalize function in an audio file, we mean that we raise its volume so that the highest level sample in the file reaches a user defined level. This is used if for example we have a lot of audio files that don't have the same volume but we want to convert all of them so that perceptually they all sound equally loud.

6) ID3 Tags:
Audio tags are used to store metadata information about the audio file such as track name, author name, duration, release year, genre, etc. Tags are very useful for identifying tracks.

7) Compact Disc Database (CDDB):
CDDB is is a database where software applications can look up CD information over the Internet. This is performed by a client which calculates a (nearly) unique disc ID and then queries the database. As a result, the client is able to display the artist name, CD title, track list and some additional information. Usually you can find information only for original Compact Disks. Use this feature to save your tracks with all the information that is available without having to enter it by hand.


4. Compressing Audio Files

After selecting the audio format that we need and the method that we like to use, it is time to take a look at how we are going to use our programs. We will analyze two ways of converting audio. Converting Audio CD tracks and converting from one audio file format to another.

Converting Audio CD tracks to a compressed audio file format
As we said in the introduction, we will be using CD-Ex for mp3 and dMC for the other formats.

Converting Audio CD tracks to MP3
1) Launch CD-Ex, go to Options/Settings and click on the "Generic" tab. Here we can set the folder that we want to use as a temporary folder, ID3 tags and normalize options.

2) Next, click the "Filename" tab and set the output folder and the way you want to sort your data. (click on the "?" to see more information about the save options).
3) Select the CD/DVD-Rom drive that you want to use from the "CD Drive" tab.
4) Now go to the "Encoder" tab and select the encoder. (We suggest you use the Lame encoder. It is fast and with very good results). Set your encoder preferences and quality options.
5) To finish he CDex configuration, go to the "Remote CDDB" tab and enter your e-mail address (or something that looks like an e-mail address - name@company.com) and click OK.
6) Insert your Audio Disk into the drive. If you can't see the tracks, press F5 to refresh the Track list. CD-Ex will then try to obtain the CD information from the CDDB. If this CD isn't on their database, you will have to enter your track details manually. Select the track that you want to edit and change the track information.
7) After this, select one (or more) tracks from the track list. To select more than one track, hold down the CTRL key while clicking. To select a range of consecutive tracks, hold down the SHIFT key while clicking on the first and last track in the range. You can select all files at once by pressing CTRL-A.
8) Click F9 to compress the tracks into MP3 files or click on the second button on the recording toolbar. (If you want to convert them into WAV, click F8 or the first button on the recording toolbar).

Converting Audio CD tracks to a compressed audio file other than MP3
For this task, we will use dBpowerAMP Music Converter - Audio CD Input. This program is much easier than CD-Ex. You can convert your audio tracks to MP3 with this program also, but there is a 30 day trial license restriction.
1) First of all, we must download and install the codecs that we want to use from dBpowerAMP Codec Central.
2) After this, open the dBpowerAMP Music Converter - Audio CD Input. It will automatically try to find information about your Compact Disk through the CDDB Database. If this disk isn't on the database, it will ask you if you want to add this CD. Click on the "Settings" button .

3) Select your output folder, the way that the tracks are going to be stored and the encoder that you want to use (don't forget to click on the settings button and change the configuration according to your needs).
4) Select the tracks that you want to convert. You can check them all or uncheck them all by clicking the right mouse button and clicking on the corresponding choice.
5) Click on the "Rip" button.

Converting from one audio file format to another
A lot of times, we want to convert an audio file into another format for compatibility reasons, so that it will work with our portable devices or you may just want to reduce the file size.

Converting an audio file to MP3
1) Open CD-Ex. If you haven't configured it yet, follow steps 1 to 5 in the "Audio file to MP3" section above.

2) Click on the "Convert/ Re-encode Compressed Audio File(s)". Select the folder that contains the files that you want to convert. Click on the "Look in subfolders" option if you want to have a list with all of your audio files from this folder and available subfolders. Check on the "Delete Original" option if you don't want to keep the original files and click "Convert".

Converting from one audio format to another
1) Open the dBpowerAMP Music Converter - File Selector. Select the files that you want to convert and click on the "Convert To" button.

2) Select the format that you want to use. Remember, you have to download and install the codec for any format you want from dBpowerAMP Codec Central before you can convert to that format. Select your encoding options, set your output folder and click "Convert".

You can select the frequency (default value is 44100Hz) with the slide bar or from the drop down list.

There is also an option for selecting channel output (Stereo, Mono, etc).



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