As non-renewable resources have less and less oil reserves, electric vehicles and hybrid vehicles are becoming more and more popular. It is believed that they will become the preferred means of transportation for people in the near future. However, because they are very quiet during driving, they pose a great threat to pedestrians or cyclists on the road, and are prone to traffic accidents.

 

The European Union has announced that on July 1, 2019, all car manufacturers will have to install AVAS systems for electric vehicles and hybrid vehicles, so that they can emit engine sounds similar to traditional cars during driving to remind others pedestrian. Voice chip voice IC.

 

software design:

 

In order to achieve the desired effect, the car sound simulator cannot simply record and play a physical car slice, and the listening experience will be very poor. It can obviously hear the transition of the splicing on the spectrum; nor can it deviate from the actual engine sound and use a fully synthesized method You can hear a clear sense of distortion.

 

Particle synthesis technology is currently the common method in larger racing games. In simple terms, particle synthesis is an audio synthesis method that divides the audio in the time domain into extremely short fragments (windows) in milliseconds, and then loops one or more fragments to obtain the exact same result as the original content. . This technology has been practiced as early as in the analog era (the name window is derived from analog synthesis), but because of its limited processor power, it has been gradually used in the digital audio field for nearly a decade.

 

The general process implemented by the engine sound simulator software is as follows:

 

1. Make or record a uniformly accelerating engine audio that covers the required speed range.

 

2. Perform fundamental frequency-to-particle synthesis analysis on all audio clips.

 

3. Particle synthesis and audio output based on the input analog.

 

Regarding the specific technology of particle synthesis, I quote a description on the Internet: The particle synthesizer is indeed not a simple segment loop. It also involves the volume envelope, segment length modulation, and time domain overlap between segments, and other issues. But the spirit I have always used to answer professional questions in non-professional situations is "ELI5 (Explain Like I'm Five)", which can be simplified without breaking the principle.