![]() ![]() Audio ArchitectureĪndroid audio architecture defines how audio functionality is implemented and points to the relevant source code involved in the implementation. These concepts are very much useful when you working on Audio HAL for different hardware devices such HDMI audio, Bluetooth SCO audio devices etc. Period size: This is the size of each period in Hz. Period: Period is the time interval between each processing frames to the hardware. PCM sound consists of a flow of sound frames.ĭata rate: Date rate is the number of bytes, which must be recorded or provided per second at a given frame size and rate. Sample Rate or simply “Rate” is defined as the number of samples per second. For example,in mono, the frame size is one byte (8 bits ). This too vary based on number of channels. Whereas in stereo(2 channel), each frame consists of two samples.įrame size: Frame size is the size in bytes of each frame. In case of mono channel sound, a frame is consists of single sample. STEREO channels: It uses more than one (usually two) signals to feed different speakers with different signals.įrame: A frame represents exactly one sample.MONO channel : It uses only one single signal to feed all the speaker. ![]() Channels are generally classified into two types. similarly for VOIP/SIP/telephone it is 8000 samples/sec and in CD it is 44100 samples/sec.Ĭhannels: An audio channel is an audio signal communications channel in a storage device, used in operations such as multi-track recording and sound reinforcement. For example,in a DVD audio 44100 samples are taken every second. To represent a actual audio signal a lot of individual samples are needed. A single sample represents the amplitude of sound at a certain point in time. Samples: In PCM audio, both input or output are represented as samples. Here are few PCM Terminology and Concepts that are used in any audio device drivers. The reverse process is called demodulation or Digital-to-analog conversion (DAC). In the below image an analog sine wave is sampled and quantized for PCM and this process is called as modulation or analog-to-digital conversion (ADC). Example : CDs, Mp3 filesĬonversion of Analog audio signals to digital audio is usually done by Pulse-code modulation (PCM).
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