LAME: Difference between revisions

Revision as of 03:07, 17 September 2011

**LAME**

LAME ain't an MP3 encoder
Developer(s)	The LAME project
Release information
Initial release	{{{released}}}
Stable release	3.98.4
Preview release	none
Compatibility
Operating system	Windows, Mac OS/X, Linux/BSD
Additional information
Use	Encoder/Decoder
License	LGPL
Website	LAME website

LAME (Lame Ain't an MP3 Encoder) is the Hydrogenaudio recommended MP3 encoder. It has been developed by the open-source community since 1998, and has become the highest quality MP3 encoder for most purposes.

Some benefits of using LAME:

Highly optimised presets
Fast encoding
CBR, ABR and quality-optimized VBR encoding methods
Gapless playback with LAME-header compliant decoders
Supported by recommended CD rippers Exact Audio Copy and CDex
Highly tunable

History

LAME development began around mid-1998. Mike Cheng started it as a patch against the 8hz-MP3 encoder sources. After some quality concerns raised by others, he decided to start from scratch based on the dist10 sources.^[1] That branch (a patch against the reference sources) became LAME 2.0. By the release of LAME 3.81, all dist10 code was removed, making LAME a completely new program, not a mere patch of an existing encoder.

The project quickly became a team effort. Mike Cheng eventually left leadership and started working on tooLAME, an MP2 encoder. Mark Taylor became leader and released version 3.0 featuring gpsycho, a new psychoacoustic model developed by him.

Nowadays LAME is considered the best MP3 encoder at mid & high bitrates, and features the best VBR model among MP3 implementations, mostly thanks to the dedicated work of talented developers like Takehiro Tominaga, Naoki Shibata, Darin Morrison, Gabriel Bouvigne, Robert Hegemann, etc. Development is ongoing.

Although LAME is generally considered to be an encoder, according to the LAME technical FAQ, it's technically not an encoder, but rather is officially just "a development project which uses the open source model to improve MP3 technology." This improved technology is only released in source code form in order to minimize the risk of violating patents. When the source code is compiled and distributed, it may require a license from Thomson, depending on where and how it's to be used. The LAME project's position is "Source code is considered as speech, which may contain descriptions of patented technology. Descriptions of patents are in the public domain."

Recommended encoder compiles and source code

Unless noted otherwise, the recommended LAME compile for optimal quality is always the latest stable version.

It is suggested that the compiles available here be used with the recommended encoder settings you can find below.

Download the latest LAME from these links:

RareWares MP3 Page - Compiles for Win32, Mac OS X universal binary, Linux etc.
LAME source code on SourceForge

Recommended encoder settings

This section describes the Hydrogenaudio recommended settings to be used with LAME for highest quality MP3 encoding. These settings require LAME 3.98 or later (the latest stable version is recommended).

Quick start (short answer)

Best quality: "archiving"

-b 320. This is the strongest setting for MP3, with the lowest risk of artifacts. With the exception of a few situations, quality is rarely better than the highest VBR profiles described below. However, 'archiving' music using a lossy format like MP3 is never recommended – no matter how transparent the resulting files might sound. The alternative is to use Lossless formats like WavPack, FLAC etc. that allow true archiving, bit for bit like on the original CD.

High quality: HiFi, home or quiet listening

-V0 (~245 kbps), -V1 (~225 kbps), -V2 (~190 kbps) or -V3 (~175 kbps) are recommended. These settings will normally produce transparent encoding (transparent = most people can't distinguish the MP3 from the original in an ABX blind test). Audible differences between these presets exist, but are rare.

Portable: background noise and low bitrate requirement, small sizes

-V4 (~165 kbps), -V5 (~130 kbps) or -V6 (~115 kbps) are recommended. -V6 produces an "acceptable" quality, while -V4 should be close to perceptual transparency.

Very low bitrate, small sizes: eg. for voice, radio, mono encoding etc.

For very low bitrates, up to 100kbps, ABR is most often the best solution. Use --abr <bitrate> (e.g. --abr 80).

--preset voice is only available in the command line front-end, and is there for compatibility. It is currently mapped to --abr 56 -mm, so that means that the recommendation would be to encode in mono, and use ABR.

Detailed explanation (long answer)

VBR (variable bitrate) settings

VBR: variable bitrate mode. Use variable bitrate modes when the goal is to achieve a fixed level of quality using the lowest possible bitrate.

VBR is best used to target a specific quality level, instead of a specific bitrate. The final file size of a VBR encode is less predictable than with ABR, but the quality is usually better.

Unlike other MP3 encoders which do VBR encoding based on predictions of output quality, LAME's default VBR method tests the actual output quality to ensure the desired quality level is always achieved.

Usage: -V(number) where number is 0-9, 0 being highest quality, 9 being the lowest.

Example: -V2

Note: The switch --vbr-new, which enabled a superior VBR mode in LAME 3.97 and some previous versions, is no longer needed with LAME 3.98 as it is now the default VBR mode. However, if you're still using LAME 3.97 or older, you have to add --vbr-new to your commandline to use that mode.

**Bitrate overview (mostly based on LAME 3.98.2 results)**
Switch	Preset	Target Kbit/s	Bitrate range kbit/s
-b 320	--preset insane	320	320 CBR
-V 0	--preset fast extreme	245	220...260
-V 1		225	190...250
-V 2	--preset fast standard	190	170...210
-V 3		175	150...195
-V 4	--preset fast medium	165	140...185
-V 5		130	120...150
-V 6		115	100...130
-V 7		100	80...120
-V 8		85	70...105
-V 9		65	45...85

If you need a predictable bitrate (in a streaming application, for example), use ABR or CBR modes, described below.

ABR (average bitrate) settings

ABR: average bitrate mode. A compromise between VBR and CBR modes, ABR encoding varies bits around a specified target bitrate.

Use ABR when you need to know the final size of the file but still want to allow the encoder some flexibility to decide which passages need more bits.

Usage: --preset <bitrate> where <bitrate> (desired averaged bitrate in kbit/s) can be any value between 8 - 320 , like eg. 9, 17, 80, 128, 133, 200 etc.

Example: --preset 200

Important: ABR setting is tuned from 320 kbit/s down to 80 kbit/s.

CBR (constant bitrate) settings

CBR: constant bitrate mode. CBR encoding is not efficient. Whereas VBR and ABR modes can supply more bits to complex music passages and save bits on simpler ones, CBR encodes every frame at the same bitrate.^[2]

CBR is only recommended for usage in streaming situations where the upper bitrate must be strictly enforced.

Usage: -b <bitrate> where <bitrate> (bitrate in kbit/s) must be chosen from the following values: 8, 16, 24, 32, 40, 48, 64, 80, 96, 112, 128, 160, 192, 224, 256, or 320.

Example: -b 192

Important: CBR setting is tuned from 320 kbit/s down to 80 kbit/s.

Remarks

The rule of thumb when considering encoding options: at a given bitrate, VBR is higher quality than ABR, which is higher quality than CBR (VBR > ABR > CBR in terms of quality). The exception to this is when you choose the highest possible CBR bitrate, which is 320 kbps (-b 320 = --alt-preset insane), but this produces the largest filesizes for doubtful audible benefit.

All modes and settings mentioned in this topic belong to the specifications of the MP3 standard, and the resulting MP3s should be playable by every MP3 decoder that conforms with the standard. If your decoder or device does not play MP3s produced by LAME, blame the manufacturer or developer, not LAME.

Avoid using alpha (a) versions of LAME. More often than not those are exclusively for testing purposes. Use them only if you want to help developers with feedback. History of Lame versions & compiles.

The --vbr-new switch enables the new VBR mode (no longer needed with LAME 3.98, as it is now the default VBR mode). In terms of quality, --vbr-new appears to be better than the old model, but reports of artifacts when using the new model do exist. Despite these possible issues, --vbr-new is currently recommended over the default VBR mode due to both the speed and quality increases afforded by the new algorithm.

-mm : the sound will be encoded in mono. Useful for low bitrates and/or when stereo is not important.

Hey! What happened to "--alt-preset"?

The revolutionary --alt-preset system was introduced in LAME 3.90; it was replaced by the --preset flags in later versions. Starting with version 3.94, the -Vx quality system was introduced, which allows finer control over the desired bitrate; the --preset switches were made into aliases to the corresponding -V flags for the sake of backwards compatibility. There is no difference between the output you get if you use -V2 or --alt-preset standard. (Although adding --vbr-new is recommended for now, see above for details.)

More encoding options are available under the new system, such as -V1, which provides a level of quality between the old "standard" and "extreme" presets, or -V3, which is between the old "medium" and "standard" presets.

Recent LAME versions feature more streamlined command-line options, and it's recommended to stick to one of the values described in the text or shown in the tables above.

For example, the following command-line options will all produce the same output:

--alt-preset insane
--preset insane
-b 320
--preset 320
--preset cbr 320

Technical information

Recommended settings details

The table below contains technical details about the recommended settings.

**Technical details of the recommended settings**
Switch	Preset	Target Kbps	Y Switch	Lowpass	Resample
-V 0	--preset fast extreme	~245		19383 Hz - 19916 Hz
-V 1		~225		18671 Hz - 19205 Hz
-V 2	--preset fast standard	~190		18671 Hz - 19205 Hz
-V 3		~175	Y	17960 Hz - 18494 Hz
-V 4	--preset fast medium	~165	Y	17249 Hz - 17782 Hz
-V 5		~130	Y	16538 Hz - 17071 Hz
-V 6		~115	Y	15115 Hz - 15648 Hz
-V 7		~100	Y	14581 Hz - 14968 Hz	32000 Hz
-V 8		~85	Y	12516 Hz - 12903 Hz	32000 Hz
-V 9		~65	Y	9336 Hz - 9602 Hz	24000 Hz

Fraunhofer decoder incompatibility

Differing interpretations of an unclear portion of the MP3 spec led to certain versions of the Fraunhofer IIS MP3 decoder being unable to properly play certain MP3s created with certain versions of LAME.

In order to demonstrate the problem, the problematic MP3 must have been created with LAME 3.97 or earlier, and must contain a frame with certain parameters and a very large amount of data, such as a 320-kbps frame which makes heavy use of the bit reservoir. The decoder must be the DirectShow filter l3codecx.ax version 1.5.0 or lower. That filter is the decoder used by Windows Media Player. The filter was upgraded to 1.6.0 by an August 2010 security update; the newer version can play the problematic MP3s.

A workaround was implemented in LAME 3.98.0 beta 1 through LAME 3.98.2, and in LAME 3.99 alpha 1, whereby 320-kbps frames were limited in how much of the bit reservoir they could use. This resulted in wasted space when the bit reservoir would grow beyond the limit. In LAME 3.98.3 and beyond, and in LAME 3.99 alpha 2 and beyond, the method was changed such that the bit reservoir can't grow beyond the limit.

Related discussion threads:

Notes and references

People who took part in suggesting the different settings:

Dibrom, r3mix, ff123, Hans Heijden, kjempen, Benjamin Lebsanft, GeSomeone, Wombat & GuruBoolez for his immense testing.

Creation of the alt preset system and related special code level quality enhancements:

Dibrom, with technical assistance from Robert Hegemann and Naoki Shibata, Gabriel and extensive tuning help and quality verification via listening tests from JohnV and also initial help (--dm-preset era) from Hans Heijden, ff123, Wombat, and others. Test clips, bitrate information, and further listening tests provided by TheBashar, zbutsam, Pio2001, BadDuDeX, r3mix, h, TarX, Hans Heijden, ff123, Wombat, Filburt, Volcano, Garf, MrDrew, TrNSZ, nyaochi, Amadeus93, in no particular order, and many, many others we (Dibrom, user) probably forgot to mention.

Idea (also exposing the need for a unified preset system), Original post and list of original settings collected by: user

Layout and additional work by: dev0, CiTay, SNYder, Dibrom.

And finally...

Thank you ALL in the community for making it what it is, providing interest and discussion and helping to work towards the most concise, well tuned, and most thought out MP3 quality "paradigm" seen yet! -- Dibrom

Footnotes

↑ dist10 is the rudimentary "demonstration" MP3 encoder described in the MPEG-2 standard, ISO/IEC 13818.
↑ Except frames of silence, which are encoded at a minimal bitrate (8 or 32, depending on MPEG version). Use -F to disable this feature.

External links

[1] st10 is the rudimentary "demonstration" MP3 encoder described in the MPEG-2 standard, ISO/IEC 13818.

[2] Except frames of silence, which are encoded at a minimal bitrate (8 or 32, depending on MPEG version). Use -F to disable this feature.

[1]

[2]

@@ Line 159: / Line 159: @@
 * '''-mm''' : the sound will be encoded in '''mono'''. Useful for low bitrates and/or when stereo is not important.
-[[Image:lame-chart-2.png|frame|center|This informal graph shows how LAME's highest quality settings result in progressively larger <font style="color:navy">file sizes</font>, but yield relatively smaller gains in <font style="color:red">perceived listening quality</font>.<ref>Discussion: [http://www.hydrogenaudio.org/forums/index.php?showtopic=32288&view=findpost&p=329935 original thread] and [http://www.hydrogenaudio.org/forums/index.php?showtopic=90464 criticism]</ref>]]
 ====Hey! What happened to "--alt-preset"?====