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Starting with Flash Player 9.0.115.0 and AIR 1.0, the runtime
can play AAC files (AAC Main, AAC LC, and SBR). A simple optimization
can be made by using AAC files instead of mp3 files. The AAC format
offers better quality and smaller file size than the mp3 format
at an equivalent bitrate. Reducing file size saves bandwidth, which
is an important factor on mobile devices that don’t offer high-speed Internet
connections.
Hardware Audio Decoding
Similar to video decoding, audio decoding requires high
CPU cycles and can be optimized by leveraging available hardware
on the device. Flash Player 10.1 and AIR 2.5 can detect and use
hardware audio drivers to improve performance when decoding AAC
files (LC, HE/SBR profiles) or mp3 files (PCM is not supported).
CPU usage is reduced dramatically, which results in less battery
usage and makes the CPU available for other operations.
Note:
When using the AAC format, the AAC Main profile is not supported
on devices due to the lack of hardware support on most devices.
Hardware audio decoding is transparent to the user and developer.
When the runtime starts playing audio streams, it checks the hardware
first, as it does with video. If a hardware driver is available
and the audio format is supported, hardware audio decoding takes
place. However, even if the incoming AAC or mp3 stream decoding
can be handled through the hardware, sometimes the hardware cannot
process all effects. For example, sometimes the hardware does not
process audio mixing and resampling, depending on hardware limitations.
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