Linear PCM VS Bitstream Audio

Audio encoding formats are essential in enhancing the quality of sound delivered by various playback devices like home theater systems, soundbars, and gaming consoles. This is because they are important for encoding and transmitting audio signals.

Two popular formats used are Linear Pulse Code Modulation (LPCM) and Bitstream, both serving to deliver high-quality sound while differing technically in their technical aspects and compatibility with different devices.

In this article, we’ll explore these differences more in-depth.

What Is LPCM?

LPCM (linear pulse-code modulation) is an audio technology typically found in digital audio applications. It is a special form of Pulse Code Modulation (PCM) in that it converts analog signals to digital format by sampling.

However, LPCMt uses different quantization techniques as it allows for splitting up an analog signal into fixed levels represented by binary codes – commonly used for DVDs or Blu-ray discs. In other words, with LPCM, the audio signals are sampled at regular intervals and quantized with a specific bit depth and sampling rate. 

What Is Bitstream?

Bitstream (compressed audio), is a digital audio format used for compressing audio data to decrease file sizes. Bitstream formats use lossy compression techniques to reduce the file size while maintaining acceptable audio quality.

Unlike linear PCM (LPCM), Bitstream doesn’t encode its audio in a linear fashion – instead, using various algorithms it reduces how much information needs to be stored.

The audio signal is encoded and compressed into a data stream that consists of bits. Once the data is encoded as bits, it is then transmitted or stored as a bitstream.

Commonly found on gaming consoles and home theater systems alike, and can even support formats like Dolby Digital and DTS for compression purposes.

Differences Between LPCM and Bitstream Audio Formats

Compression

One of the primary differences between LPCM and Bitstream audio formats is compression. While LPCM remains uncompressed and unchanged by the use of algorithms for shrinking file sizes, Bitstream compression reduces file sizes through the use of algorithms.

File size

Since LPCM audio files tend to be uncompressed, their size tends to be greater than Bitstream files, meaning you will likely fit fewer LPCM audio files on a storage device compared to Bitstream files.

Quality

In general, LPCM audio is considered of higher quality than Bitstream due to the fact that its format doesn’t alter or compress data in any way; while Bitstream employs compression algorithms that may compromise audio quality.

Compatibility

Most audio devices support LPCM audio with low sampling rates; however, some devices do not. Bitstream, on the other hand, is often found in gaming consoles and home theater systems but not all formats of it are supported on every device.

Sampling Rates

LPCM can support sampling rates that span from 44.1 kHz to 192 kHz; however, some devices may only support audio with higher sampling rates. Bitstream audio usually uses an encoded sampling frequency of 48kHz for optimal listening experience.

Bit Depth

LPCM supports various bit depths from 16-bit up to 24 bit depths while bitstream encoded at 16 bit is more commonly the norm.

Channel Support

LPCM supports various channel configurations, such as mono, stereo, and surround sound playback. Bitstream may support surround sound; the exact channel configurations depend on which compression format was employed.

Dynamic Range Control

LPCM does not employ dynamic range control to adjust audio levels according to the playback device or playback format, meaning that its audio signal must be delivered as is. Bitstream, on the other hand, may employ this function for optimizing playback quality and playback device compatibility.

Bitrate

LPCM uses a fixed bitrate calculated from sampling rate and bit depth calculations; bitstream has a variable bitrate depending on compression format used and complexity of audio data stored within.

Latency

LPCM tends to have lower latency than Bitstream audio data because LPCM audio data can be transmitted and decoded live; with Bitstream files needing to be decompressed before playback can begin.

Which One Is Best?

The answer to this question depends entirely upon each specific use case and individual user preferences. If audio quality is of top priority, LPCM would likely be superior as it provides uncompressed sound with no loss in quality; but for file sizes or compatibility reasons with gaming consoles or home theater systems (for instance), Bitstream might offer compression as well as support for surround sound systems.

Conclusion

Both LPCM and Bitstream audio formats differ considerably when it comes to their compression, file size, quality, compatibility, sampling rates, bit depth, support channels, support dynamic, range control, bitrate, and latency. While audiophiles often prefer uncompressed formats with higher quality such as LPCM for their listening pleasure, Bitstream may be seen more commonly used with gaming consoles and home theater systems due to its lower latency characteristics. For a more general comparison, check out our article on PCM vs Bitstream.