Audio Encoding

Posted: March 22, 2012 in Uncategorized
Tags: ,

MP3 Encoding
LAME Engine (Windows)
These packages contain all versions;
EXE, DLL, lameACM, lameDS, lame-libsndfile, and the Lamedrop GUI

LAME 3.99.5
LAME 3.99.5 UPX compressed versions
LAME 3.99.5 64bit
Individual files available from RAREWARES
Linux and Mac versions also available.

LAME Graphic User Interfaces (GUI)
RazorLame (old but still very useful. Easy to save your own profiles.)
LameXP (also encodes other formats)

What you need to know about using MP3
Motion Picture Experts Group is a branch of "Joint Picture Experts Group" (JPEG) who made the *.JPG picture format.
It is the property of the Fraunhofer Institute. There are free versions from other developers.
It does not encode the best quality or the smallest, so why do we use it?
Just about every electronic device is capable of playing MPEG files. It is the most standard portable media format.

MP3 is not MPEG-3 ! There is no MPEG-3 !
WHAT ? How can this be?

Motion Picture Experts Group first version of MPEG was used for video discs (VCDs).
Music fans realised the MPEG audio format was ideal for compressing large audio files, as it packs the file a block at a time.

*NOTE* ZIP and RAR for example, compress the whole thing in one go.
Compressing data streams a chunk at a time, from front to back is known as Run Length Encoding (RLE)
Without this method we would not have streaming media (Imagine an internet with no YouTube!).

The audio stream in these early MPEG-1 files is known as "MPEG-1, Layer 2". (I used this format back in the Amiga days, and still have the files.)
These files were usually saved as "*.mp2" or "*.mpa". They became widely known as MP2, which would later cause confusion on Windows PCs.

The use of it as a stand-alone audio compressor, prompted the further development in this direction, and a new third MPEG layer was created.
“MPEG-1, Layer 3”, is the format that we still now use, though It is still continually being developed and tweaked by a few coding groups.
This new audio format could make much smaller files at the same quality settings, and with the growing size of hard drives it became far more common for people to copy whole CDs to their computer! (wow imagine that)
These files are almost always saved as "*.MP3", but as you can see they are actually still based on the original MPEG-1.

Motion Picture Experts Group second version of MPEG was used for Digital Video Discs (DVDs).
MPEG-2 allows much higher quality encoding.
There is an audio encoder that uses “MPEG-2, Layer 3” called "MP3Pro" (Nero supports this format). Unfortunately it is not standard, and most media players do not play them correctly, because they are also always saved with the "*.mp3" extension. They contain both a 44K and a 22K stream, but most players only see the 22KHz one.

History lesson over.

What quality settings should you use?
Depending on the source and/or destination this will vary, but once you know one thing it becomes easy.
💡 CDs are equal to MP3 at 44100Hz (frequency), 170k (bit rate).
DVDs audio is at 48000Hz and variable bit rates

Now you have your standard, you can decide whether your file needs to be above or below CD quality.
Digital encoders tend to have steps in their bit rate settings, and you will notice that there is no 170k bit rate for MP3.
💡 This is why you see a lot of files encoded at 160k or 192k.
A CD ripped with a Constant Bit Rate (CBR) of 192k, should contain all of the audio you started with.
Unfortunately MPEG is a lossy format, and to achieve such small file sizes it uses ancient magic to discard audio that is calculated you won't miss.
If you max the bit rate to 320k you will keep the quality, but at the cost of huge files.

💡 A more sensible way to store quality audio, is using Variable Bit Rate (VBR).
Setting a minimum and maximum allows the encoder to compress quiet sections of audio at low bit rates, and complex or loud audio at high bit rates.

The audiophile group at the old R3Mix forums came up with the ideal settings for CD quality MP3.
💡 Min:96k Max:224k and a VBR Quality setting of 1. The quality setting tells it to prefer or bias the quality one way or the other. 0 is the highest and 10 the lowest.

If you are mastering your own music, then you need to think about whether you should be using a higher quality setting.
If you want to distribute CD quality files, then the R3mix settings are perfect.
If you want to distribute higher than CD quality files, then the maximum of 320k (CBR or VBR) should be set.
If you want to distribute DVD quality files, then you should export them at 48000Hz and encode them at 320k.
If you want files for a streaming music service such as Last.fm they should always be in 44100Hz and at least 128k CBR.
Variable Bit Rate is ideal for streaming, due to the smaller files, but sometimes a file with a very quiet beginning can confuse the site you upload to, as the beginning of the file will have a low bit rate, it sometimes gets rejected. All you can do is export it again using CBR, or raise the minimum bit rate a step.

Most modern programs on Windows, Linux and Mac can and do make use of the “LAME” MP3 engine.
It has several built-in profiles (inc. R3mix), your software may support them.
WinAmp is always very up to date with the latest LAME encoder, and supports the profiles.

If you copy the “lame_enc.dll” and “lame.exe” files to your C:WindowsSystem32 folder, many programs that are well written can use it (Exact Audio Copy is a good example). Otherwise you usually have to put it in the programs own folder (the plugin folder for WinAmp).
Many programs just require you to point them at it, and many just find it automatically.
Audacity has its own version you must get 😦

EXTRA RESOURCES
Hydrogenaudio Forum http://www.hydrogenaudio.org
AfterDawn Forum http://forums.afterdawn.com/forum_view.cfm/37

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