Bitrate – How Does it Affect Audio Quality and File Size?
In the video, a variable bit rate allows you to split the difference between file size and quality by processing different amounts of information per frame. This saves on data by only pushing new data to those elements in a scene that change significantly from frame to frame. So what does bitrate mean? Bitrate is the amount of data transferred in a digital file. It is commonly expressed in kilobits per second (kbps), megabits per second (Mbps), or other metric prefixes.
Bit Depth
Bit depth is the number of amplitude values that can be recorded for each sample in an audio file. A higher bit depth means more resolution, but it also results in larger files.
To understand how bit depth affects audio, you must first grasp how digital audio works. To do so, consider that an acoustic sound wave is a continuous movement of energy passed through a medium (typically air).
When recording digitally, this information is converted into fragmented measurements represented as binary data (1s and 0s) and called samples. A higher bit depth produces a higher resolution sample closer to the analog sound source it’s meant to replicate.
A lower bit depth, on the other hand, results in a lower signal-to-noise ratio. This can be a problem, especially when the recording is played back at high volumes.
For this reason, it’s often recommended to record in 24-bit, as the extra bit depth provides more headroom when you turn up the gain with a clipping plug-in. Each bit of audio represents 6 dB of dynamic range.
It can be easily distorted and ruined when you manipulate audio at a lower bit depth. This is because there are fewer amplitude values for each pulse to assign. This makes the resulting signal brittle and noisy.
Sample Rate
When recording audio, we use a sample rate to determine the number of samples (tiny slices of audio information) that are used within one second. This is the same concept as a camera’s frame rate – more frames per second means more fluid motion and lifelike images.
A higher sample rate allows us to capture more of the original analog sound waveform, resulting in more accurate audio reproduction. It also reduces the amount of high-frequency aliasing and filter-induced distortion in the audio signal.
However, high sample rates may cause your audio to sound slowed down or slightly lower-pitched. This happens because your system reads the samples faster than it should, causing them to have a slightly lower-pitched amplitude value than the original analog sound.
Similarly, a high sample rate can increase the file size of your digital audio files. This increases the amount of data that needs to be stored on your computer’s hard drive, which can add up over time.
Another important consideration is that some affordable soundcards need to work better with higher sample rates, which can result in unwanted jitter. This is a real concern for anyone who wants to use high-resolution audio on their desktop computer or stream audio north of 192kbps to headphones.
Audio Compression
Audio compression reduces the size of sound files by removing parts of the audio that are less audible and redundant. This can be done by either converting an audio file from one format to another or recompressing existing files.
There are two main types of audio compression: lossless and lossy. Lossless compression does not remove any sound data from the original file and can be reversed, whereas lossy compression permanently deletes the data.
The type of audio compression you choose depends on the purpose for which you are using it. For example, if you’re working with a song with a lot of low-end energy, you could use a compressor with fast attack and release times to attenuate the low-end.
File Size
Bitrate measures the amount of audio data that is transferred or processed at any given time. The higher the bit rate, the more audio data available and the higher the file’s quality.
It can also be used to compare the quality of different file types. While it is possible to tell the difference between a high-bitrate and a low-bitrate audio file, several factors can affect the overall quality of the music.
One of these is the file format itself. Many file formats are designed to compress data, which saves space on a hard drive or network storage medium.
Typically, these files have a lower bit rate than other audio formats. This is because they use a type of compression known as lossy encoding.
Lossy encoding works by analyzing the sound and discarding certain aspects that aren’t deemed important to the overall listening experience. This method can significantly reduce the size of an audio file, but it comes at a price.
Another factor that can impact the file size of a song is the sampling rate. A higher sampling rate can result in a larger file, but it can also cause problems with clarity and detail.