A sound recorder does not have a frame rate because sound does not have a frame rate.
Understanding how sound is recorded digitally can help clarify this. Unlike video, which captures a series of still images (frames) per second to create motion, digital audio recording captures thousands of samples of the sound wave's amplitude per second.
Sample Rate vs. Frame Rate
- Sample Rate: This is the number of times per second that an analog audio signal is measured and converted into a digital value. It determines the fidelity and frequency range of the recorded sound. Common sample rates include 44.1 kHz (for CDs) and 48 kHz (standard for video and film production). A higher sample rate means more detail is captured, resulting in higher quality sound.
- Frame Rate: This is the number of still images (frames) displayed per second in video or film. Standard frame rates include 24fps (film), 25fps (PAL), 29.97fps (NTSC), and 30fps. A higher frame rate results in smoother motion in video.
Key takeaway from the reference: "Sound does not have a frame rate, its speed is determined by the sample rate."
How Sound and Video Stay in Sync
Even though sound recorders don't have a frame rate, sound recordings need to synchronize perfectly with video recordings which do have a frame rate. This is achieved by ensuring both the audio and video recordings reference the same timing information, often managed through timecode.
The reference illustrates this: "If a production sound mixer is recording at 48k while the camera is running 24fps, then the 48k sound will be in sync with picture being played back at 24 fps."
Here's a simple table summarizing the concepts:
| Feature | Sound Recording | Video Recording |
|---|---|---|
| Primary Measure | Sample Rate (e.g., 48kHz) | Frame Rate (e.g., 24fps) |
| What it Measures | Samples per second | Frames per second |
| Determines | Audio quality/fidelity | Smoothness of motion |
Therefore, when discussing the technical specifications of a sound recording, you would refer to its sample rate, not its frame rate. The frame rate is a characteristic solely of video.
