Blu-Ray sound

The sound on Blu-Ray has received a boost compared to regular DVD at the introduction of several new audio formats from Dolby and DTS. Here you get a full overview of audio systems for Blu-Ray.

Blu-Ray supports the same formats as DVD does. This means Dolby Digital and DTS. It is mandatory that Blu-ray players can decode or send out these audio formats from the player.

Multichannel PCM
The disadvantage of audio systems such as DVD use is that they are compressed in relation to the original soundtrack is PCM. PCM stands for Pulse Code Modulation and is an uncompressed technique for digital audio. It is this technique used on regular CDs, but with 2 channels. On Blu-Ray used the PCM with 6 or 8 channels (5.1 / 7.1). Today's modern films produced with 24-bit PCM 48 kHz sampling with 6 channels (5.1)

To accommodate such a sound system on a DVD would cause the sound would take the space of a movie in about two hours. (24-bit PCM audio at 48 kHz sampling frequency takes about 50 MByte per minute).

With 50GB of storage, Blu-ray room to be able to use 24 bits / 48 kHz PCM audio and even have 30-40GB accommodate film depending on length of the film. Therefore it is a good part of the films that use PCM audio. Most bitdypden change to 16 bits. This reduces the need for space for about 35 Mbytes per minute.

It is mandatory for all Blu-ray players to support multichannel PCM over HDMI to the receiver / processor. It's not all receivers with HDMI, supporting multichannel PCM. An overview of receivers / amplifiers that can handle MPCM sound can be found here.

Dolby TrueHD To prevent sound takes so much space, but also to retain the sound quality Dolby developed a so-called lossless lydsystemsom they call for Dolby TrueHD. This sound provides the ability to retain the sound quality from the original PCM soundtrack without taking up the same space on the disk as a PCM audio track will do. Dolby TrueHD can be encoded with 24 bits or 16 bits of accuracy and bit rate is variable, but is about 1.5 Mbit / s in average by 16 bits and about 3.5 Mbit / s at 24 bit 5.1 sound. This is about half of what similar PCM signal takes. Maximum sound quality that can be used on Blu-ray is 7.1 audio with 24-bit bit depth and 96kHz sampling frequency. It is doubtful whether it will ever come releases with that sound.

To transmit Dolby TrueHD signal to a receiver / processor must use HDMI connection where the player and receiver supports version 1.3 of HDMI. An overview of receivers and amplifiers that supports decoding of Dolby TrueHD can be found here. The range of Blu-ray players that can output Dolby TrueHD signal you can see here.

If you do not have a decoder in hjemmekinoreceivern for Dolby TrueHD, there are other opportunities to experience this quality. First possibility is that the player has internal decoding of Dolby TrueHD so that it can send the audio out via a 5.1 or 7.1 analog output and connected to the corresponding input on your home receiver. Another option is that the player can decode the audio into PCM to then send PCM audio via HDMI to receieren. This is also a voluntary system so that there be no requirement for support for this system in Blu-Ray players. That is why many of the first Blu-ray players that do not give you any opportunity to enjoy Dolby TrueHD sound.

Movies equipped with Dolby TrueHD is mandatory to attach a 640 kbit Dolby Digital soundtrack. If you have equipment that does not support Dolby TrueHD will automatically be rendered this soundtrack if one chooses Dolby TrueHD sound.

Dolby Digital Plus
Dolby Digital Plus is also a new format developed for high-definition formats. Unlike Dolby TrueHD is Dolby Digital Plus is not lossless. This means that you can lose something sound quality compared to the original. Dolby Digital Plus offers up to 7.1 audio and encoded on the disc with up to 1.7 Mbit / s which is far more information than the DVD standard offers via Dolby Digital. This audio format is in practice not in use on Blu-Ray releases.

DTS-HD Master Audio
DTS-HD Master Audio is just like Dolby True HD a lossless audio system for up to 8 dedicated channels. (7.1). DTS-HD Master Audio allows up to 18 Mbp / s bitstream. DTS-HD Master Audio support sound 7.1 audio code for up to 24 bit / 96 kHz. Currently there are few publications that have this sound system on Blu-Ray. Because of the lossless technique is Dolby True HD and DTS-HD Master Audio equal when it comes to sound quality såfremst they use the same bit resolution and sampling frequency. As Dolby True HD can only This audio system is transferred to the receiver via HDMI version 1.3. Alternative is to transform the signal to multichannel PCM or down-converted to standard DTS audio with a bitrate of 1.5 Mbit / s.

Compared to Dolby TrueHD has DTS-HD Master Audio advantage that it is built up in a different way. DTS HD Master Audio consists of a DTS Core soundtrack of 1500 kbit containing one compressed 5.1 soundtracks. In addition comes a track that contains information that can do this DTS Core soundtrack that lossless DTS-HD Master Audio track. The advantage of this is that the players and equipment where there is no support for DTS-HD Master Audio so you can use DTS Core track that is compatible with all Hjemmekinoreceivere who have regular DTS decoding. 1500 kbit is twice as high bitrate used on most DVD releases with DTS sound and ensures a relative sound quality.

DTS-HD High Resolution Audio
DTS-HD High Resolution Audio can deliver up to 7.1 channels of audio in top quality. Bitrate on HD-DVD can be up to 6 Mbit / s, but it most releases with this sound system is about 1.5 Mbit / s. Also here is the quality be up 96kHz sampling rate with 24 bits bit depth. There are very few titles that have been released with this audio system on Blu-Ray.

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