Audio sample rate conversion (SRC) or audio resampling is the process of changing the audio sample rate without affecting the quality. Broadcast audio infrastructure equipment typically requires 48-kHz synchronous sampling rate audio signals. However, the audio inputs to the audio equipment can be from sources with different sampling rates. For example, CD audio signals have a sampling rate of 44.1 kHz, while other audio sources have sampling rates from 32 kHz to 192 kHz.
Altera’s SRC core was developed and optimized for Altera® devices and comes with demonstrations for Altera development boards. The audio SRC converts audio signals with different sampling rates into a single, synchronous audio stream sampled at 48 kHz. The design can accept audio signals in either AES3/EBU or I2S format and can be targeted to the low-cost Cyclone® series FPGAs or the high-performance Stratix® series FPGAs. Typical applications of the audio SRC are digital mixing consoles, broadcast studio equipment, and audio workstations.
Figure 1 shows the audio sample rate converter block diagram.
Figure 1. Audio Sample Rate Converter
Features and Benefits
- Broadcast quality performance
- 24-bit resolution, -130 dB THD+N 32-kHz to 192-kHz input rates
- Senses input sample frequency automatically
- Output sampling frequency range from 32 kHz to 192 kHz
- Support for up to 16 audio channels (8 stereo pairs)
- MegaWizard® Plug-In configurable
- Easy-to-use IP toolbench interface
- Automatic output mute during error condition
- AES3/EBU channel status interfaces (in and out)
- Bypass and secondary mute implemented externally
- AES3/EBU and I2S interface support
- Cost-effective solution
- Can be implemented in both low-cost Cyclone and high-performance Stratix device families
Altera has verified the SRC intellectual property (IP) through software simulation and extensive hardware testing with the state-of-the-art audio analyzer. For more information on this core, contact your local Altera® sales representative.