Bitstream is also known as Bitstream Audio, Bit Stream, Digital Bitstream, or Audio Bitstream and it is the latest technology to get the music, dialogue, and sound effects from a source to the ears. In fact, Bitstream is a system of digital-to-analog signal conversion and it is used in some audio CD players. In this technology, the signal is digitally processed to give a signal at a higher frequency before being converted to an analog signal.
What is Bitstream Audio?
Bitstream is a sequence of binary digits (1’s and 0’s) that can be transferred from one device to another and it is transmitted continuously over a communications path. Bitstream is mostly used in PC, networking, and audio applications. In audio technology, Bitstream converts sound into digital bits and then transfers the information from a source device to a receiver, and finally the ears of the listener.
Bitstream Audio Management for Home Theatre
In a home theatre, a Bitstream audio management is mostly used as a method to transfer encoded audio signals of specific surround sound formats from a source to a compatible home theatre receiver or AV preamp/processor/Power amplifier combination, etc. Generally, a home theatre receiver or AV processor first detects the encoded audio signal and then decodes the signal based on instructions provided in the Bitstream signal. It may also include post-processing and then the signal is converted to analog form. Finally, the signal is amplified and sent to the speakers and you can hear the sounds.
The first step of creating a Bitstream sound signal is to decide what surround sound format to use for a specific audio recording. Then, the next step is to encode the audio as digital bits in the chosen format as every format has its own rules. Once the process is completed, you have to place the bits on a disc; streaming source, cable, or satellite service, or you can also embed the encoded audio signal in live TV transmission. Many surrounded sound formats use the Bitstream transfer process that includes Dolby Digital, EX, Plus, TrueHD, Atmos, DTS, DTS-ES, DTS 96/24, DTS HD-Master Audio, and DTS:X. You can transfer the Bitstream directly to the home theatre through a physical connection. You can also send the Bitstream wirelessly via antenna or home network.
Example of Bitstream Audio Management
Here is how Bitstream audio management works:
Usually, a DVD, Blu-ray, or Ultra HD disc contains the sound signal that is encoded as digital bits. The disc player reads the encoded signal from the disc and then transfers it in Bitstream form via digital optical, digital coaxial or HDMI connection to a receiver. The receiver then decodes the Dolby Digital or DTS Bitstream into its proper channel assignments and then transfer them through the appropriate amplifiers and then finally to the speakers.
The disc player can also decode the Bitstream coming from a disc internally to the PCM format. In this method the receiver won’t decode the Bitstream coming from a player; instead, it will send a decoded signal in PCM form digitally and directly to a home theatre receiver via HDMI or in analog form through multichannel analog audio connections. In this process, the decoders of the receiver will automatically bypass the audio signal passing directly through the receiver. So it won’t require additional processing unless the listener activates the receiver/AV processor.
TV stations transmitted the Dolby Digital-encoded Bitstream and the TV receives the signal and then transfers it to a soundbar, home theatre receiver, etc. Then these devices will decode the Bitstream and play the decoded signal. Depending on the device a user might have the option to combine the decoded Dolby Digital result with additional audio processing.
Different video streaming services like Netflix offer a program or movie encoded in Dolby Digital or related surround sound format. If the media streaming is connected to a home theatre receiver using a digital audio connection then the audio Bitstream signal is sent to the receiver. Then the signal is decoded and sent through the amplifier and speakers. If the media streamer is connected to a TV and the TV is connected to a home theatre or soundbar then the TV will pass the Bitstream signal out to the soundbar/home theatre for decoding and amplification.
If you receive Netflix or other streaming services through a Smart TV then the Smart TV will pass an encoded Dolby Digital signal to a soundbar or home theatre. The smart TV will follow the same procedure as normal TV and when it receives the signal.
What is PCM?
PCM stands for Pulse-code modulation. This technology is used to digitally represent sampled analog signals. PCM helps convert the analog information into a binary sequence and it will resemble a binary sequence. PCM is mostly used as audio in computers, compact discs, digital telephony, and other digital audio applications. The PCM technology has been around for more than 100 years and it is still considered as the standard for transmitting audio streams. PCM is an algorithm and it can send compressed or uncompressed audio files that are very convenient.
Which one is better: Bitstream or PCM?
PCM and Bitstream are two industry standards of sending audio from the player or transmitter to the receiver or speaker. Both the PCM and Bitstream can produce the same quality but the difference is how your setup decodes the compressed file. Some devices make better use of PCM than Bitstream but the newer AVRs can take the better advantage of Bitstream’s decoding process. So, if you have to pick from the Bitstream and PCM then you have to consider the compatibility with devices and supported frequencies, sound, transmission, etc.
When you are using the PCM technology the device will decode the file before sending it to the receiver. Almost every device that converts the digital signal to an analog audio output uses this technology to deliver audio files. Then, the player will send these decoded audio files, to all the receivers connected to your home theatre system or soundbar.
When you are using Bitstream you will have fewer options for audio transmission compared to PCM. There is not much difference between the audio quality of PCM and Bitstream but you will get better frequencies from Bitstream audio signal. Unlike the PCM, in Bitstream technology; first, the player will transmit compressed audio files to the receiver. Then the receiver will decode the data for uncompressed output. Bitstream is best for surround sound formats.
Detailed Comparison of Bitstream and PCM
|Compatibility||Compatible with most players that are available, including CD, DVD, and Blu-ray players.||Compatible with high-end modern players that fully supports most surround sound formats.|
|Audio File||Players convert analog signals to digital and vice-versa for transmission to the receiver.||Audio files are bit encoded, and it follows a specific surround sound format for digital transmission.|
|Decoding||Players handle the decoding of audio files, and then transmit the data to the receiver for output.||Players transmit compressed audio files to the receiver, which is responsible for decoding data.|
|Connection||Transmission of audio streams requires a physical connection from the player to the AVR and speaker.||Transmission of audio streams can be wired or wireless, as long it’s from a compatible media player.|
|Audio Output||Transmission requires much higher bandwidth to reduce quality degradation with better output.||Transmission offers better flexibility for receivers and speakers to deliver high-quality audio output.|
|Secondary Audio||Provides better support for hi-res secondary audio channels.||Secondary audio quality is good, but options may be limited.|
|Transmission||Works with players and receivers that support analog and digital sound transmission.||Only works with players and receivers that support digital sound transmission.|
|Optical / Coaxial||Support for digital optical or coaxial output is limited.||Support for digital optical or coaxial output can go up to 5.1.|
When Should You Use PCM?
You should use PCM configuration if:
- You’re looking for a way to unlock high-quality secondary audio
- You want a faster and direct connection that minimizes latency for output
- You want to relieve your receiver from the burden of converting audio files
- You’re using a sound system that favors the decoding of audio files from the player
When Should You Use Bitstream?
Using Bitstream for your audio is better if:
- You want to take advantage of 5.1 surround sound when using digital optical or coaxial
- You want to give your sound system better flexibility in playing hi-res audio
- You’re using a receiver that offers better audio processing power
- You have a sound system that relies on the receiver to decode and process files
There is no clear winner from Bitstream and PCM. Which one you should pick depends totally on your needs. If you are trying to setup hi-res secondary audio, PCM is a better option for you. But if you are building a sophisticated sound system then Bitstream will be the best option.