MP3 File Format
What is MP3 ?
MP3 is an audio compression technique that allows you to compress audio
by a ratio of between 1:4 and 1:12 and still keep the original quality
of the sound. The sound retains the CD like quality and will end
up as a file many times smaller than the original .WAV size.
Sound samples by MP3
If you have found my homepage you also like this kind of music. Because this music
is no longer created it is difficult for people to know of its existance.
People like me who don't hear it on the radio, have no idea of the existance of certain
bands and groups that created this music.
MP3 allows the transfer of audio files over the internet at minumum size, for the
purpose of EVALUATION ONLY so we can decide if to buy the CD or not..
I encourage the transfer of sound samples as this gives us the opportunity to test music
we normally don't have the chance to, and if we do decide it is good, go and order the
original CD.
MP3 evaluation also encourages the sale of music to a greater number of customers.
Who can play MP3 ?
All that is needed to play MP3 files is a pentium computer with soundcard
running Windows 95 and a program like WinPlay (or Winamp).
Alternatevly you can decode the original .WAV file with a decoder like
L3DEC and play it under DOS or Windows with your soundcard software.
Who can create MP3 ?
To create an audio file encoded MP3 you need an audio source in .WAV format.
This can be the sample from a soundcard (Low quality) or the source can
be songs ripped off CDs (The preferred method).
You need a CDROM that can read raw audio sectors, enough diskspace (raw
audio takes up about 10Mb per minute), you also need an encoder like
L3ENC. To rip music off CDs you need a program like CDDA or DAC.
Not all CDROM drives support reading of raw audio sectors off CDs.
Most of the drives sold today can do it, and all SCSI drives can read
audio. All CD-R drives can copy audio.
What drives support raw audio sector copying ?
Here is a partial list of drives I know support reading audio CDs.
This list is based on feedback from people I'm in touch with. If your
drive supports DA sector reading, and is not in the list, please
let me know.
Apple 300, 300i, 300e
Sony CDU-8003, CDU-8003A, CDU-8012
Apple CD300+
Chinon CDS-535
COMPAQ CR503/CDU561
DEC RRD42
Goldstar GCDR-540 IDE
HP 4020
NEC CDR 200, 300, 400, 500, 600, 900 series
NEC CDR 84-1/74-1 (rumoured with special firmware)
Panasonic CR-562B/563B/572/574/581
Pinnacle RCD1000/5030
Pioneer 124/624
Plextor 4Plex/6Plex
Sanyo C3G IDE
Sony CDU-561, CDU-31A, CDU-33A, CDU-55S, CDU-55E, 76E/76S
Toshiba XM3301 (Silicon Graphics)
Toshiba XM3401, XM4101, (XM3501 with 0925 and later firmware), 3601, 5302
Hitachi
Matshita (Panasonic) 503
Yamaha CDR100/102
Kodak PCD225,6x
Philips CDD522
Plasmon RF4100
JVC XRW2001
Ok, how do I do it ?
Encoding and decoding MP3 is easy if done right. You will get a very high
quality audio file that takes up a fraction of what the original did.
You have only to follow these simple instructions and you'll do it in
minutes.
1.
Get the CD source. You can use DAC or CDDA or any other software you
like. DAC must be run under DOS (not a DOS window). You will get menu
with a list of tracks on the CD. You select the track you want and press
F2 to copy it to a filename you specify.
CDDA in my opinion is better. It is a command line utility that can
run under DOS or Windows (in a DOS window).
I prefer running it under DOS.
You specify the line
cdda.exe /t 2 /f filename.wav /w /o
to rip track 2 to a wav file called filename.wav.
/t 2 - means that I want to record track number 2
/f filename.wav - means to write to File - filename.wav
/o - copy protection override - must me used for audio
/w - means that format must be WAVe
and there you have it ! The song is now a WAV file.
2.
You now need to encode the file to MP3 format. For this you need
a program like L3ENC. Using this utility the command line would be :
l3enc filename.wav filename.mp3 -br 128000 -hq
-br 128000 - means, the file will be converted at bitrate 128Kbit/s
(the minumum for music)
-br 192000 - gives you better quality, very near to CD quality
-br 256000 - gives you true CD quality
filename.wav - input file filename.mp3 - output file
filename.mp3 - this is the name of the MP3 file you will get.
-hq this means high quality. You don't have to use this option
but you get better quality sound if you do use it.
You will now have a file called filename.mp3 .
This file is still sampled at 44.1KHz stereo, 16 bit , just like
the origanal WAV, only 10 times smaller !
You can now delete the WAV file which is not needed anymore.
That's it, easy isn't it ?
The MP3 file which you now have can be played back with Winplay by you
or anyone else who has a soundcard. If you want to decode the original
WAV back from the MP3 you would type
L3DEC filename.mp3 filename.wav -wav
filename.mp3 - the file you want to decode
filename.wav - the destination WAVe file
-wav = this means to create a WAVe file
Now you'll get a file called filename.wav .
If you want a sample
If you'd like a sample of this kind of music, go to the main page
and view my music list. Tell me the names of the songs you'd like,
I'll send it to you by ftp to a server you find (I have no FTP space).
If you like it please go buy it in your record store, or over the
internet stores. I want to encourage you to buy this stuff, not
copy it. If you decide not to buy the CD, delete the sample.
I am also looking for this kind of music, if you have something I
don't have, send me a sample, I'm always looking for new CD's
to buy.
What Software should I get ?
I have mentioned many different programs here, which is best ?
Ripping CD's audio tracks is the first step.
This can be done with many programs.
I have a CDROM that allows the extraction of raw data and have tested
two programs, DAC and CDDA.
DAC is a program that must run under DOS (not a DOS window).
You will get a window with the list of tracks found on the disc.
Move the cursor to the track you want and copy it with F2 to a filename
you specify.
CDDA can be run under DOS or windows. This is a command line wtility
which gives you total control over how you rip the track.
I would suggest using the default values as the program knows what it
is doing and in most cases this gives optimum performance.
You copy the audio track by following the steps I wrote in a section
above. The copying of audio with this program can be highly optimized
by creating a batch file that does all the work for you.
Here is a sample batch file that I use for copying audio tracks
the batch files is called CP.BAT
cdda /t %1 /f %1 /w /o
cdda /t %2 /f %2 /w /o
cdda /t %3 /f %3 /w /o
cdda /t %4 /f %4 /w /o
cdda /t %5 /f %5 /w /o
If I want to copy tracks 1 3 5 6 9 I would type the following line
CP.BAT 1 3 5 6 9
after which the program copies the selected tracks to the filenames
1.WAV 3.WAV 5.WAV 6.WAV 9.WAV
It's as simple as that !
Next you should find an encoder.
There are a few freeware encoders that do the job well. The program
I found most suitable is called L3ENC. This program is shareware.
The trial version allows you to sample at miximum 112KBs, which is not
the optimum for music, this is however enough to allow you to try the
program before you buy it.
To get true CD quality you have to encode your WAV file at a bitrate
of at least 128000. For this you need a registered version of
the L3ENC encoder software. With the registered version you can create
MP3 files encoded at bitrates of up to 256000 . This gives you a file
of true CD quality, at full stereo, 44.1KHz, 16 bit.
L3DEC is the decoder that gets the original WAV out of the MP3 file.
You also need a player for MP3 files. The minimum hardware recommended
is a 486DX50 computer. A pentium is needed for stereo samples.
If you have an older computer that cannot keep up with the CPU intensive
real time players you could always decode the MP3 and play the WAV
file later - even on a 386 machine. Use your souncard software to play
the WAV file, or any other software found easily on the web (shareware
and freeware utilities are widely available).
A little technical stuff... more than you probably wanted to know.
What is to follow might be very boring for some readers and can quite
happily be skipped. I'll try to give as accurate description of the audio
compression technology as possible including the various sampling
techniques. At the moment I don't have much time to give much detail but
I hope to fill it in as soon as possible.
The method is called PSYCHO-ACOUSTIC COMPRESSION which means the file being
played does not contain the whole sound sample actually recorded (As in a
WAV file), but only the parts of the music the human ear, and brain can
distinguish from the music. This is somewhat like a picture in which you
reduce the resolution up to a point where the eye can barely make out the
difference. This of course saves valuable disk space.
The source file is split into a few key frequencies and a volume sample is
taken, this resembles the spectrum analyzer you have in graphic equalizers,
only this is the other way around. This way you make up the "resolution" of the
sample , ie. the number of bits in the .MP3 file. For example in a 128KBs
sample you have 128000 bits of information per second, not recorded as sampled
digital music , but as music volumes at different frequencies. The more bits
you have per second , the more accurate the reproduction of sound you get.
This is not exactly correct as there are different ways of creating the optimum
file. For low resolution samples, those 56KBs and below speech samples, the
entire acoustic spectrum is not sampled, only the frequencies referring to
speech are taken into account, thus saving valuable unused samples not included
in the human voice. In this way we reduce the size of file without affecting
the quality of speech. This method is good only for speech as the entire audiable
spectrum is not reproduced.
The medium sized samples (96KBs and 112KBs) use a different algorithm than used
for speech. Here we want to get a wider range of frequencies and still keep the
file small. The highest quality samples (128KBs, 192KBs, 256KBs) work a little
different.
More to come if time permits.
Final words ...
I hope this has helped you, I'm sure you'll enjoy this new audio standard
which is both high quality and not space consuming.
Let me give you one final word of warning,
Copying of audio is both unethical and illegal.
Hearing music samples for evaluation is ok, if you like what
you heard, go buy it !
I want this music to spread, allowing more people to know of it's
existance, MP3 is the perfect way. Sending samples across the globe
breaks the barriers of distance, please don't take advantage of
this technology to create piracy.
Today there are quite a few music stores on the web allowing you to
directly download songs as MP3. This saves you the expenses of shipping,
also giving you immediate access to a wide range of songs of your choice.
Almost for free, for the first time ever, you can buy music, from your
own home, only at the time it takes you to download the files.
With such excellent service, you can forget about the costly music stores
and get exactly what you want, exactly now. This saves you lots of
money, as you save on shipping and the price it costs to own a store.
This should give you enough reason to go and buy a song you like
instead of stealing it.