MP3: LAME DLL

MP3 compression is probably the most popular format ever for sharing audio over the Internet. MP3 has become so popular that manufacturers already started making stand alone MP3 players so you can listen to your favorite MP3s even without a computer nearby. The music industry tries to bring down MP3 as being illegal which is absolutely not true! MP3 is here, and it is here to stay. That is until a much better compression format arrives of course :)

In this part of the tutorial we will use the LAME DLL encoder.

For people reading the whole tutorial at once several parts on this page will be familiar already. It's just copy/pasted from the external LAME encoder part of the tutorial. I didn't feel liking writing a whole new story about it. I could of course leave it away and put links to the external LAME encoder part of the tutorial to clarify things, but some people are too lazy to check those out and then bug me with stupid e-mails complaining about missing information.

Original started as LAME Ain't an MP3 Encoder, a patch to the ISO encoder to avoid legality issues with Fraunhofer LAME has evolved to one of the best MP3 encoders available. In many tests LAME comes out as best and surpasses Fraunhofer which has been the reference encoder for years. At r3mix.net you can find comparisons & tests between LAME and other popular encoders. LAME comes out as the best and thus is LAME the preferred MP3 encoder if quality is your goal. LAME supports both constant bitrate encoding and variable bitrate encoding, and is very fast too. LAME is distributed as source code only, but some sites offer compiled versions. The latest win32 compiled binaries can be found at Dmitry Kutsanov's website.

LAME comes as an executable (EXE) and a Dynamic Linked Library (DLL). While both give identical output, the executable version of LAME is preferred because EAC has the ability to pass custom parameters to the executable allowing you to make use of all of LAME's parameters. The DLL can only use a few predefined settings. Anyway, for most people those predefined settings satisfy so I'll explain the usage of the DLL here. If you want a more configurable LAME encoder use the external executable version of LAME. The advantage of the DLL is real-time encoding. The external encoder has to wait for a track to be extracted completely to WAV first before the encoding can begin. DLL based encoders or codecs can encode in real time without extracting to a temporary WAV first.

Important:

Since LAME 3.88 r3mix.net recommends a LAME command-line using advanced parameters which EAC cannot pass to the LAME DLL. Therefore you better use the external executable version of LAME. 

Obtain the LAME DLL encoder

As said earlier LAME is distributed as source code. Now for most people source code is useless, but you can get the latest win32 compiled binaries at Dmitry Kutsanov's website. 

At the moment of writing LAME 3.89 is the latest version. Download LAME 3.89. Check Dmitry Kutsanov's website regularly for new updates of the encoder! After downloading the zip file, decompress lame_enc.dll to your harddisk using WinZip or similar. It's recommended to put lame.exe in the c:\windows\system folder on a Windows 95/98/ME system, and c:\winnt\system32 on Windows NT/2000 systems. Why? Then the LAME DLL can be shared between other programs supporting the DLL. If you do not ant to put LAME in the mentioned directories you must place it in the same directory as the Exact Audio Copy executable eac.exe. Otherwise EAC will not be able to detect lame_enc.dll.

Configuring EAC for the LAME DLL encoder

Make sure you have Configured The Compression Options in Exact Audio Copy.

From The EAC menu select Compression Options... or press F11. This opens the Compression options window.

Make sure Use external program for compression is disabled on the External Compression tab. Otherwise you are not able to select the LAME DLL encoder. Then on the Waveform tab select LAME MPEG Layer-3 Encoder v3.87 DLL v1.16 from the Wave format drop down box. Depending on your version of the DLL the version and build information may differ. Also note that a new tab has appeared in the Compression options window: the LAME DLL tab. If you cannot see this new tab and cannot select the LAME DLL from the dropdown box, lame_enc.dll is probably not at the correct location.

Enable Add ID3 tag if you want to take advantage of the ID3 tag features. The ID3 tag saves extra information like artist name, track title, album title into the MP3 file. The newer ID3v2 tag (which is also supported by EAC - see Configuring The Compression Options) can store even more extra information and gets rid of ID3v1's 30 characters limitation.

Check Do not write WAV header to file to avoid the writing of a WAV header. MP3 cannot be wrapped by a WAV header. Therefore this option must be enabled.

Enter .mp3 in the File extension for headerless files. Note the dot (point) before the extension. It is necessary to put the dot in front of the letters mp3.

On the LAME DLL tab make sure Insert CRC Checksum is disabled. While LAME is one of the few encoders which actually supports the CRC check correctly it has little use. Because most encoders' implementation of this feature is not working correctly, most players ignore the CRC check. Besides that, enabling this option adds 16 bits (the CRC value) to every MP3 frame!

The Write Xing VBR header on VBR encoding should be enabled. For most people knowing something about MP3 quality the name Xing gives them pimples and is associated with low quality MP3s. But if Xing invents a good thing it may be said. The Xing header helps MP3 players to identify a file as a Variable Bitrate file. It will of course only be written to Variable Bitrate files.

Setting the LAME encoding options

LAME can be configured in EAC by selecting the bitrate from the Sample format drop down box on the Waveform tab. Unlike with the highly configurable external executable version of LAME, there is no possibility of overriding these settings with custom parameters. As mentioned before we will use the r3mix.net recommended settings for MP3 encoding. r3mix.net has done extensive tests with the LAME encoder and defined the optimal settings for the best quality.

LAME supports both Constant Bitrate encoding (CBR) as Variable Bitrate encoding (VBR). CBR encoding uses the same bitrate in every frame through the whole file. VBR on the other hand changes the bitrate of every frame according to the complexity of the audio data in that frame. Complex signals will force LAME to use a higher bitrate, while simple signals force LAME to use a lower bitrate to save space. VBR encoded files can have the same quality as a CBR encoded file while the file size is a lot smaller. You can say that Variable Bitrate encoding is the more efficient one. The drawback of Variable Bitrate encoding is that it is way slower to encode, and not all players and decoders (correctly) support it. Therefore, if file size is no issue for you avoid VBR and use Constant Bitrate encoding instead. With the prices of storage media these days, file size shouldn't be an issue for most people.

Important LAME parameters

In this small section I'll discuss the most important and common used LAME parameters. LAME has a lot more parameters you can use but the DLL implementation in Exact Audio Copy does not allow to use those. The parameters passed to LAME are also shown below, but you cannot see those. It's all wrapped in a nice user interface.

• Sample format: In this drop down box you can specify the bitrate. -b n: Set constant bitrate (bitrate: n = 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 kbit/s). The higher the bitrate, the higher the quality.
  Below the CBR bitrates in the drop down box you can find the VBR settings. If you want to use Variable Bitrate encoding you must select one of the bitrates with VBR in the name. When using VBR, the selected bitrate is the minimum allowed bitrate. This is useful to prevent LAME VBR from using some very aggressive compression which can cause some distortion due to small flaws in the psycho-acoustic model.
• Output mode: In this drop down box you can select the stereo mode used by LAME. -m n: Set stereo mode (stereo mode: n = m (mono), n = s (stereo), n = j (joint stereo) and n = f (forced mid/side stereo)).
  Mono is the default mode for mono input files. If -m m is specified for a stereo input file, the two channels will be averaged into a mono signal.
  Joint stereo or jstereo is the default mode for stereo files with fixed bitrates of 160 kbit/s or less. At higher fixed bitrates, the default is stereo. For VBR encoding, jstereo is the default for VBR quality > 4, and stereo is the default for VBR quality <= 4. You can override all of these defaults by specifying the mode on the command-line.
  Jstereo means the encoder can use (on a frame by frame bases) either regular stereo (just encode left and right channels independently) or mid/side stereo. In mid/side stereo, the mid (L+R) and side (L-R) channels are encoded, and more bits are allocated to the mid channel than the side channel. This will effectively increase the bandwidth if the signal does not have too much stereo separation.
  Mid/side stereo is basically a trick to increase bandwidth. At 128 kbit/s, it is clearly worth while. At higher bitrates it is less useful.
  Using mid/side stereo inappropriately can result in audible compression artifacts. To much switching between mid/side and regular stereo can also sound bad. To determine when to switch to mid/side stereo, LAME uses a much more sophisticated algorithm than that described in the ISO documentation.
  Forced mid/side stereo forces all frames to be encoded mid/side stereo. It should only be used if you are sure every frame of the input file has very little stereo separation.
• Quality: In this drop down box the encoding quality can be set. Since the best quality is what we need only set this to High Quality. -h: Enables specialized mid/side masking thresholds to be used in jstereo mode. Will sound better in jstereo mode but is about 20% slower. -h also enables a more accurate but slightly slower quantization formula. Since high quality is our goal, this parameter should always be used.
• Maximum VBR bitrate: Here you can specify the maximum bitrate used by Variable Bitrate encoding. -B n: Set maximum allowed bitrate (bitrate: n = 32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320 kbit/s). The higher the bitrate, the higher bitrates can be used and thus the higher the quality. By default LAME uses the maximum of 320 kbit/s as highest allowed bitrate. For high quality encoding it is not recommended to lower this value!
• Use VBR quality: The lower the variable bitrate encoding quality number, the higher the quality of the encoded file. Thus a variable bitrate encoding quality number closer to 0 will force LAME to encode at a higher quality (use bitrates above the minimum allowed). -V m (variable bitrate encoding quality: m = 0, 1, ..., 9) and set the minimum allowed bitrate (bitrate: n = 8, 16, 24,... , 320 kbit/s).

High quality Constant Bitrate encoding settings

r3mix.net recommends 256 kbit/s high quality stereo encoding. See the screenshots on the left for an example.

When uploading to newsgroups or FTPs 256 kbit/s MP3s are sometimes considered as a little bit overkill. Most people do not hear the difference between 192 kbit/s encoded files and 256 kbit/s. Therefore you may choose to use -b 192 -m s -h instead. 192 kbit/s is nowadays the preferred bitrate for Internet distribution. However, for personal use, or if you just care about quality always go for 256 kbit/s.

High quality Variable Bitrate encoding settings

LAME is currently the only MP3 encoder optimally tweaked for Variable Bitrate encoding unlike Fraunhofer and which does not mess up like Xing. For VBR encoding r3mix.net recommends somewhat more advanced settings: -V 1 -b 128 -m j -h -q 1. Now here's the problem with the DLL. The -q 1 switch cannot be used when using the DLL. That is the reason why I do not recommend the usage of the LAME DLL for Variable Bitrate encoding. You better use the external executable version of LAME. The extra -q 1 switch is another quality/size switch. It is said to replace the -h switch when using VBR. This is what r3mix.net has to say about it: -q 1 saves you a lot of bits without real quality concessions. I use it with -V 1, and never had a bad experience with it. It makes the encoder rely more on the psycho-acoustics model, yielding less bits for the same quality. There are reports of -q 1 combined with variable bitrate quality parameter -V higher than 4 giving poorer results, but since -V 1 is what I use, not much of a problem I think.

The closest to r3mix.net's settings you can get is -V 1 -b 128 -m j -h. Joint stereo is used. some people claim that joint stereo is not good. But this only applies to the Fraunhofer and Xing encoder. LAME offers perfect tweaked joint stereo encoding. Why not using -V 0 for even higher quality? -V 1 -b 128 -m j gives a perfect balance between quality and space (about 160 to 190 kbit/s). If you use -V 0 (or -m s) you end up with a file of about 220 kbit/s. Due to the imperfect nature of the psycho-acoustic model and quantization algorithms of a perceptual encoder, you can better opt for the safe 256 kbit/s CBR solution if you don't mind ending up with such large files. Using -V 0 does not sound better than a fixed 256 kbit/s encoding as stated in the Lame manual.

See the screenshot on the left for an example of using the -V 1 -b 128 -m j -h setting.

When you are sure the settings are correct for your needs click the OK button. EAC is now configured to extract to high quality MP3 files. See Extracting Tracks To Your Harddisk for more information about this.