HandBrake, a famed open source video transcoder, gave the latest update for version 0.10.5 on February 11, 2016 bringing improvements on x265 and large AVI handling, but announcing bad news that FDK AAC encoder has been removed from this new version due to license issue. Meanwhile, new questions should be answered. What AAC encoder does HandBrake use now? Does this current HandBrake AAC encoder deliver superior or lower audio quality than FDK AAC encoder? Here, we will help you solve those puzzles.
What Is FDK AAC Encoder?
FDK AAC, originally developed for Android and later expanded to other platforms, is recognized as one of top AAC encoders to encode and decode AAC format audio with high quality following Apple AAC. It arrives with several cross-platform versions. fdk-aac (latest version 0.1.4) is based on FDK AAC 3.4.12/2.5.10) and includes a shared library libfdk-aac. fdkaac (latest version 0.6.2) is an advanced front-end to the FDK AAC encode using libfdk-aac, while FFmpeg/Libav support is a wrapper for libfdk-aac available for use with FFmpeg.
FDK AAC supports 8 audio object types: AAC-LC, HE-AAC, HE-AAC v2, AAC-LD, AAC-ELD, MPEG-2 AAC LC, MPEG-2 HE-AAC, MPEG-2 HE-AAC v2. The bitrate can reach up to 96 kbps per stereo channel and 112 kbps per mono channel. Sample rates for input of 8000 – 96000 Hz are supported. And, the library is now limited to 16-bit integer PCM input due to fixed-point math.
What're Current HandBrake AAC Encoders?
Although FDK AAC has disappeared from HandBrake 0.10.5, it has no influence for Mac but makes a bit change for Windows and Linux. Now, check the list of AAC encoders HandBrake uses at present.
Libav (AAC): It is a fork of FFmpeg project focusing on handling multimedia data. It includes numerous video/audio encoders and decoders for most mainstream formats, for example AAC. Libav is now the default HandBrake AAC encoder.
Core Audio (AAC/HE-AAC): It is a library offering a set of frameworks for developers to handle audios on macOS and iOS. HE-AAC delivers high compression efficiency and is optimized for low-birate applications for audio streaming. It is only used for HandBrake Mac version.
Is Current HandBrake AAC Encoder for Windows Superior than FDK AAC?
Native FFmpeg AAC encoder (Libav AAC encoder) was declared going to stable for general use in December 2015. The test results indicate that this AAC encoder is transparent at 128 kbps and delivers equal or greater quality than most of other encoders. In February 2016, FFmpeg released a major version 3.0 including greatly improved AAC encoder without experimental flag.
Because of above changes, native FFmpeg AAC encoder is considered as best FDK AAC encoder alternative for HandBrake. However, HandBrake's announcement explicitly told the default Libav AAC encoder "is lacking in comparison to FDK but is passable for most" and does not support HE-AAC. Hydrogenaudio Knowledgebase, a great place for learning audio technology, also gives similar conclusion that the current HandBrake AAC encoder (FFmpeg 3.0 AAC encoder) cannot preserve as much quality as FDK AAC and receives a mid-rank on recommended list.
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