The files get encoded with information that allows the gap heard between files to be removed. This is what Ahead have done with their Nero AAC codec. However, certain companies can choose to add gapless encoding/decoding if they desire, providing it doesn't break compatibility with previous decoders. Gapless playback is not part of the AAC standard and as such is not mandatory. See the Audio format guide for more information.ĭo AAC encoded files play back gaplessly? ffmpeg's AAC, considered experimental at the time of the test, came in dead last.īeyond that, only you can decide you may want to conduct your own private listening tests, or you may base your decision on other criteria besides audio quality. Fraunhofer IIS (via Winamp 5.62) came next. Internet Profile for Nero AAC) or above (based on Roberto's listening tests, see bottom).Ī public listening test conducted by IgorC in July 2011 comparing Nero, QuickTime True VBR, QuickTime Constrained VBR, Fraunhofer IIS (via Winamp 5.62), Coding Technologies (via Winamp 5.61), ffmpeg's AAC, at 96kbps, concluded that QuickTime was the best codec among the 6 codecs. It can also be said with great confidence that both the iTunes AAC encoder and the Nero AAC encoder are relatively 'mature' and should not fail badly (result in any obvious artifacts) on any particular sample at an average bitrate of 128kbps (i.e. The quality of any encoder is not linear with bitrates, and therefore these results may not be extrapolated to other higher or lower bitrates. Since it is very difficult to quantify the quality of an encoder, listening tests are used.Ī public listening test conducted by rjamorim in mid-2004 comparing different codecs, at 128kbps, with several music styles and featuring several listeners concluded that iTunes (the only AAC codec included in the test) was better than other codecs - even VBR-enabled ones.
S Source code available L Linux M macOS W Windowsĭeciding the best AAC encoder is difficult, because the quality of an encoding depends not only on the encoder implementation, but also on bitrate, audio content, playback equipment and conditions, and the subjective perceptual judgement of the listener at playback time.
Libav (pre-3.0 FFmpeg) AAC encoder S/L/M/W What's the best AAC encoder? Current AAC encoders The HE Object Type is only used for music with a bitrate of less than ~80kbps.
Currently, Apple, Nero, Coding Technolgies, and Panasonic have incorporated the HE AAC standard into their encoders, which allows for higher quality sound at lower bitrates than the LC Object Type does (at the same bitrate). LC is the most popular Object Type with all encoders/decoders supporting it. These are two of the various Object Types in the MPEG4 Systems Standard. What is the difference between LC (Low Complexity) and HE (High Efficiency)? It will not accept unwrapped AAC files (files with the.
The iPod accepts files with the MP4 extension, the M4A extension, the M4P extension (a Protected AAC file), and the M4B extension for audiobook files (which can be either protected or unprotected). What MPEG 4 extensions does the Apple iPod Accept? As far as the internal structure of the file, nothing is different. Apple came up with extension to distiguish between files with Video and Audio (the MP4 extension) and files with Audio only (the M4A extension). What is the difference between *.MP4 and *.M4A? īesides the extension, absolutely nothing. It usually offers (depending on the codec) equivalent quality to MP3 at a lower bitrate. To improve upon and replace MP3 as the defacto Audio Encoding standard. Overview AAC FAQ Great, so you've given me all the technical stuff, but what is AAC really? ĪAC is the culmination of the current state of the art audio encoding techniques. 1.8 What hardware players can play back AAC music?.
1.7 What software players can play back AAC music?.1.6 Do AAC encoded files play back gaplessly?.1.4 What is the difference between LC (Low Complexity) and HE (High Efficiency)?.1.3 What MPEG 4 extensions does the Apple iPod Accept?.1.2 What is the difference between *.MP4 and *.M4A?.1.1 Great, so you've given me all the technical stuff, but what is AAC really?.