The Blu-ray disc format provides an enhanced viewing experience and enhanced sound quality for listening. Blu-ray disc players provide several setting options for audio and video output, depending on how physically connected your turntable to a home theater receiver . We compared bitstream and PCM so you can get the best sound quality from your Blu-ray disc player.
General conclusions
Bitstream
-
The receiver decodes the audio.
-
Potential for higher sound quality.
-
Limited secondary audio quality.
-
Support 5.1 over digital optical or coaxial.
PCM
-
The Blu-ray player decodes the audio.
-
More bandwidth is required.
-
Better for secondary audio channels.
-
Limited digital optical or coaxial output.
For audio, if you connect your Blu-ray Disc player to your home theater receiver via HDMI two main audio output settings are available: Bitstream and PCM (also called LPCM). In terms of sound quality, whether you set the HDMI audio output of the Blu-ray PCM player or the bitstream is irrelevant. However, here’s what happens when you choose any option.
Although the discussion below focuses on bitstreams versus PCM in relation to Blu-ray Disc players, the same information can be applied to Ultra HD Blu-ray Disc players .
PCM pros and cons
Benefits
-
Decoding is done in the Blu-ray player.
-
Less work for the recipient.
-
Faster, straighter and eliminates lag.
-
Better quality access to additional audio tracks.
Flaws
-
More work done by the player.
-
The sound quality is partly determined by the Blu-ray player.
-
PCM transmits a two-channel signal via digital optical or coaxial.
If you set your Blu-ray disc player to output PCM audio, it will internal audio decoding for everyone sound tracks associated with Dolby / Dolby TrueHD and DTS / DTS-HD Master Audio . It then sends the uncompressed decoded audio signal to the home theater receiver. As a result, the home theater receiver will not perform additional audio decoding until the audio has been passed through the amplifier and speaker section. With this option, the home theater receiver displays the term PCM or LPCM on the front panel display.
If you plan to use the secondary audio feature, which provides access to audio commentary, descriptive audio, and additional audio tracks, use PCM. If access to these audio programs is important to you, please set your Blu-ray player to PCM for the best experience. The player decodes the audio without bandwidth issues, which is a bitstream issue.
For digital optical and coaxial connections, while the bitstream output option can send a standard Dolby Digital or DTS 5.1 surround sound signal to a receiver for decoding, the PCM option sends a two-channel signal. A digital optical or digital coaxial cable does not have enough bandwidth to carry decoded, uncompressed, full surround audio as can be done with an HDMI connection.
Bitstream Pros and Cons
Benefits
-
The home receiver decodes the audio.
-
If the receiver offers better sound processing, you can use it.
-
Possibility of better sound quality.
-
The bitstream sends a 5.1 encoded signal over digital optical or coaxial.
Flaws
-
More work posted on the receiver.
-
A high quality receiver is required for best results.
-
The extra audio is reduced, which lowers the quality.
If you select Bitstream as the HDMI audio output setting for a Blu-ray player, the player bypasses its internal Dolby and DTS audio decoders and sends an unencoded signal to a home theater receiver connected via HDMI. The home theater receiver performs audio decoding of the incoming signal. As a result, the receiver will display Dolby, Dolby TrueHD, DTS, DTS-HD Master Audio, Dolby Atmos , DTS: X or another format on the front panel display depending on what type of bitstream signal is being decoded.
Dolby Atmos and DTS:X surround sound formats are only available from the Blu-ray Disc player via the bitstream setting option. There are no Blu-ray disc players that can decode these formats internally to PCM and stream them to a home theater receiver.
If you combine the bitstream and secondary audio settings, the Blu-ray Disc player will convert downsampled surround sound formats such as Dolby TrueHD or DTS-HD to Dolby Digital or DTS to compress both types of audio signals into the same bitband flow. , In this case, the home theater receiver recognizes the signal as Dolby Digital and decodes accordingly.
HDMI is the best option for output. However, if you are using digital or optical coaxial outputs, bitstream is the clear winner. Digital optical and coaxial connections suffer from limited bandwidth and cannot carry a fully processed and decoded signal. Since the bitstream depends on the receiver for decoding, it is ideal for situations with limited bandwidth.