Last Updated on January 7, 2023 by Norvan Martin
In modern audio systems, audio is encoded in digital formats such as MP3. In the olden days, digital encoding was done in though a single channel called mono. Today, most music is recorded on two audio channels (left and right) to be played back on a stereo system like two speakers or a pair of headphones. The way this is done drastically changes the sound quality of your file audio files and this is why joint stereo vs stereo is important.
In this article, we will explain what stereo and joint stereo are and the advantages and disadvantages of each.
What is the difference between joint stereo and stereo?
In stereo mode, MP3 encodes the Left and Right channels separately into an audio file which increases the resulting bitrate (bitrate can be distributed between Left/Right as needed). “Joint Stereo” is a method used to save space while still maintaining a stereo signal by mixing the Left and Right channels into a Mid channel and a side channel.
Read on to learn more.
What Is The Difference Between Joint Stereo And Stereo?
Stereo is a method used to produce sound from two audio channels – the right and left channels simultaneously. When loudspeakers are used, the music appears to come from two directions at once.
In normal stereo mode, MP3 stores separate Left and Right channels and can, therefore, be used to play different signals on each separate channel. In most cases, the channels are encoded separately into an audio file which increases the resulting bitrate.
This kind of sound is so much layered that it is also known as three-dimensional. Besides, the device that plays this kind of sound is also called stereo, like a stereo radio for example.
In general, stereo is generally recommended if you’re encoding audio at a bitrate of 256kbps or higher.
Joint stereo is a method that sound engineers use to save file space while maintaining the integrity of the stereo signal. This is done because stereo files can be unnecessarily large as in most cases, the audio input into the Left and Right channels are pretty much the same.
With joint stereo, the two stereo channels (Left and Right) are converted to two channels of L+R (called Mid) and L-R (called Side) in a lossless and reversible process. In other words, joint stereo mixes the Left and Right channels into a Mid channel.
How Does Joint Stereo Work?
Because the data in the left and right channels are similar, when audio is exported as a joint stereo file, the media encoder is able to find the average of the Left and Right channel data and merge this into a smaller file.
Joint stereo provides great benefits (in terms of small file size) at a lower MP3 bitrate because the amount of data being averaged is already significantly lower.
The Advantages Of Joint Stereo
- Usually, the Left/Right channels are similar. Therefore, most of the information appears in the Mid channel, while only a few pieces of information go to the Side channel.
- The redundant part doesn’t have to be stored twice.
- Can use the available bits more efficiently than normal stereo mode.
The Advantages Of Stereo
- It helps to prevent phase interference between speakers
- A more immersive listening experience. Therefore, you do not perceive sound to be coming from one speaker but from the space between them.
- Interaural level difference.
The Cons Of Joint Stereo
- Only advantageous at lower MP3 bitrates and less helpful at higher bitrates
- Not suitable when the Left and Right channels are totally different such as having a French dialog track on the Left and an English one on the Right.
The Cons Of Stereo
- Expensive and more complex to set up. This is because you need separate signals signal chains, amplifiers, and different speaker circuits.
- Not practical with the spoken word.
- Interference between the Left and Right signals occurs when plaid through a mono system.
Stereo Vs. Joint Stereo Vs. Dual Channel
Let’s begin by comparing stereo with dual channels. If you use dual channels regularly, then you already know that it fixes the bitrates of each channel so that every channel gets precisely half of the bitrates for the entire length of your audio.
For instance, if you play 384 kbits/s stereo audio, a dual-channel track will send exactly 192 kbits/s to the Left channel and 192 kbits/s to the Right channel.
On the other hand, standard stereo basically allocates bitrate to the channel that appears to have more need for it. For instance, if the R channel is silent and the L channel has audio, the stereo will allocate most of the combined bitrates to the L channel.
Now, joint stereo mode takes into account the redundancy between the L and R channels to optimize coding.
However, the stereo quality of joint stereo audio varies with the stereo image of the coded signal and is particularly suited to low bit rates only. Therefore, the use of joint stereo should be reserved for applications requiring low bitrates such as transmission.
Joint Stereo Vs. Stereo Vs. Mono
Traditionally, people mainly did music recording on a single channel, also called mono. Most modern music is, however, recorded on two audio channels so that it can be played on a stereo system such as a pair of headphones.
Also, the digitization of audio into MP3 files has made it easier to manage the amount of data encoded or the bitrate depending on how the encoding is intended. In addition, it makes it easier to differentiate between stereo and joint stereo.
As we already mentioned, joint stereo pays more attention to the redundancy between L and R channels and is suitable for transmitting low bitrates only. The method is mainly used to save file space while still keeping the signal integrity of the stereo.
Therefore, the media encoder finds the average of the data in the Left and Right channels and merges it into a smaller file. However, the advantage you get depends on the amount of content you have.
On the other hand, stereo sends different audio signals to the L and R channels based on the need and is mainly recommended for encoding audio at 256 kbps or higher.
This is different from mono as the mono mode is only applicable in single-channel audio or where the L and R signals need to be separated into two different files to make it easier to operate on them independently.
Joint Stereo Vs. Mono
Joint stereo combines the Left and Right channels of your sound output into Mid and Side while mono produces sound in one channel only.
Although you can still send mono signals into a pair of headphones, it remains mono as the same audio signal is fed to both speakers simultaneously.
The concept of joint stereo was notably used in MP3 recordings. Generally, MP3 files compress data and help save on storage space and reduce download times. Joint stereo helps achieve similar results.
So, is joint stereo better than mono? Before answering this question, consider a situation where all your tracks are mono, such as speech podcasts. In this case, the track should be encoded in mono to achieve the best results.
Therefore, whether joint stereo is better than mono? The answer is, it depends on the tracks you intend to listen to and your listening situation.
Mono Vs. Stereo
As we said already, mono sound is obtained when you use only one channel to convert the signal to sound, while stereo uses multiple channels to produce sound.
Even if you have multiple speakers, the same signal is sent to both speakers when using mono. The ear, therefore, feels the sounds are coming from one position, even though they are coming from different speakers.
Stereo, on the other hand, sends unique signals to every speaker. When listening to the stereo, the ear feels the effect of sound coming from different sources and positions. This is typical of today’s technology, especially in surround sound effects.
Which is better? It all depends on your preference and situation. If you are watching a movie, the stereo will be the best sound format as it will give you the best sound effects to feel as if you are in the movie. However, if you like to wear only one earphone, you may prefer mono.
Stereo Vs. Joint Stereo and Bitrate
Bitrate refers to the amount of data (amount of bits) a digital audio file contains per second (kilobytes per second or kbps). When people refer to bitrate, they often use the term to convey the quality of compressed audio formats.
The higher the bitrate, the more information that file holds, the better the quality, and the less compressed it is.
You can manage the bitrate of your audio depending on how you want your DAW to encode the files.
Should I Use Stereo or Joint Stereo?
Your choice of stereo or joint stereo when encoding depends on the file size you need as well as the output quality you are looking for.
It also highly depends on the compression engine that you are using because some compression engines are better at encoding audio in joint stereo while others do not.
You should also consider the bitrate size you’re aiming for. In general, if it’s over 256kbps, consider using stereo. Under 256kbps, you can try a joint stereo. In any case, always run tests to see which sounds better and which file size is better for you.
The choice is entirely yours whether you use stereo, joint stereo, or mono in encoding your music track. This is because it all depends on your listening preferences, environment, and available equipment to encode and play the sound. However, if your bitrates are higher than 256kbps, we recommend sticking with stereo.
Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics.