HD-Audio Explained
The advent of HD video content has seen a corresponding switch to HD-Audio. You will see much mention of the various confusing standards. This page attempts to explain in relatively easy to understand terms what it's all about. Two competing companies have issued standards for HD-Audio, Dolby and DTS (Digital Theatre System), these will be dealt with in turn.
Dolby Digital (Also known as AC-3)
Dolby Digital is a required standard of both Blu-Ray and DVD and the most widely supported HD-Audio format, being supported by all the Media Players on our site. It is a 'lossy' format so is of a lesser quality than the original cinema/studio original. Surround sound up to 5.1 channel is supported. The Dolby Digital audio track can either be decoded (downmixed) to stereo in the Media Player or digitally bitstreamed direct (passthrough) to a compatible receiver (via TOSLINK/Coaxial/HDMI) for decoding.
Dolby Digital Plus (E-AC3)
Dolby Digital Plus is an enhanced version of Dolby Digital offering higher bit-rates and the possibility for 7.1 surround sound. Although better quality than Dolby Digital, it is still a 'lossy' format. Dolby Digital Plus is little used and has largely been passed over in favour of higher quality lossless formats.
Dolby TrueHD
Dolby TrueHD is a lossless compression format giving audio identical to the original studio recording. It can handle 14 separate channels for surround sound. Dolby TrueHD is completely separate from Dolby Digital AC-3, so files carrying TrueHD audio must also carry a separate AC-3 track to make them playable on non TrueHD players. Dolby TrueHD can either be downmixed in the player to an analogue format, or bitstreamed via HDMI 1.3 or higher* to a compatible receiver.
*TOSLINK or Coaxial S/PDIF cannot carry a TrueHD signal because the S/PDIF standard was finalised long before lossless HD-Audio was envisaged (despite S/PDIF being theoretically able to cope with the bandwidth). HDMI 1.3 or higher is therefore the only way to pass Dolby TrueHD audio.
DTS (Digital Theater System)
DTS is a required standard of both Blu-Ray and DVD players and is widely regarded to produce audio quality superior to Dolby Digital. Up to 5.1 channel surround sound is supported. DTS is a 'lossy' compression standard so the audio is of a lesser quality than the original studio recording. Until recently many Media Players did not support DTS so you would get no audio at all when playing back files with a DTS audio track (many .mkv files). The DTS audio track can either be decoded (downmixed) in the Media Player to stereo or digitally bitstreamed direct (passthrough) to a compatible receiver (via TOSLINK/Coaxial/HDMI) for decoding. Any decent new Media Player will be able to both downmix and passthrough DTS.
DTS-HD HR (High Resolution / DTS+)
DTS-HD High Resolution is an enhanced version of DTS offering higher bit-rates and better compression. Up to 7.1 channel surround sound is supported. It is still a 'lossy' format and is not widely used, having been largely passed over in favour of lossless formats. DTS-HD HR uses a core+extension format so if your player doesn't support DTS-HD HR then the DTS core can be extracted.
DTS-HD MA (Master Audio / DTS++)
DTS-HD Master Audio is a lossless compression format giving audio identical to the original studio recording. It supports up to 8 channels for surround sound. Unlike Dolby TrueHD, DTS-HD MA works in a core+extension configuration so players that do not support it can extract the DTS core audio. DTS-HD MA can either be downmixed to an analogue format if supported by the player, or bitsreamed via HDMI 1.3* to a compatible receiver.
*TOSLINK or Coaxial S/PDIF cannot carry a DTS-HD MA signal because the S/PDIF standard was finalised long before lossless HD-Audio was envisaged (despite S/PDIF being theoretically able to cope with the bandwidth). HDMI 1.3 or higher is therefore the only way to pass Dolby TrueHD audio.
The advent of HD video content has seen a corresponding switch to HD-Audio. You will see much mention of the various confusing standards. This page attempts to explain in relatively easy to understand terms what it's all about. Two competing companies have issued standards for HD-Audio, Dolby and DTS (Digital Theatre System), these will be dealt with in turn.
Dolby Digital (Also known as AC-3)
Dolby Digital is a required standard of both Blu-Ray and DVD and the most widely supported HD-Audio format, being supported by all the Media Players on our site. It is a 'lossy' format so is of a lesser quality than the original cinema/studio original. Surround sound up to 5.1 channel is supported. The Dolby Digital audio track can either be decoded (downmixed) to stereo in the Media Player or digitally bitstreamed direct (passthrough) to a compatible receiver (via TOSLINK/Coaxial/HDMI) for decoding.
Dolby Digital Plus (E-AC3)
Dolby Digital Plus is an enhanced version of Dolby Digital offering higher bit-rates and the possibility for 7.1 surround sound. Although better quality than Dolby Digital, it is still a 'lossy' format. Dolby Digital Plus is little used and has largely been passed over in favour of higher quality lossless formats.
Dolby TrueHD
Dolby TrueHD is a lossless compression format giving audio identical to the original studio recording. It can handle 14 separate channels for surround sound. Dolby TrueHD is completely separate from Dolby Digital AC-3, so files carrying TrueHD audio must also carry a separate AC-3 track to make them playable on non TrueHD players. Dolby TrueHD can either be downmixed in the player to an analogue format, or bitstreamed via HDMI 1.3 or higher* to a compatible receiver.
*TOSLINK or Coaxial S/PDIF cannot carry a TrueHD signal because the S/PDIF standard was finalised long before lossless HD-Audio was envisaged (despite S/PDIF being theoretically able to cope with the bandwidth). HDMI 1.3 or higher is therefore the only way to pass Dolby TrueHD audio.
DTS (Digital Theater System)
DTS is a required standard of both Blu-Ray and DVD players and is widely regarded to produce audio quality superior to Dolby Digital. Up to 5.1 channel surround sound is supported. DTS is a 'lossy' compression standard so the audio is of a lesser quality than the original studio recording. Until recently many Media Players did not support DTS so you would get no audio at all when playing back files with a DTS audio track (many .mkv files). The DTS audio track can either be decoded (downmixed) in the Media Player to stereo or digitally bitstreamed direct (passthrough) to a compatible receiver (via TOSLINK/Coaxial/HDMI) for decoding. Any decent new Media Player will be able to both downmix and passthrough DTS.
DTS-HD HR (High Resolution / DTS+)
DTS-HD High Resolution is an enhanced version of DTS offering higher bit-rates and better compression. Up to 7.1 channel surround sound is supported. It is still a 'lossy' format and is not widely used, having been largely passed over in favour of lossless formats. DTS-HD HR uses a core+extension format so if your player doesn't support DTS-HD HR then the DTS core can be extracted.
DTS-HD MA (Master Audio / DTS++)
DTS-HD Master Audio is a lossless compression format giving audio identical to the original studio recording. It supports up to 8 channels for surround sound. Unlike Dolby TrueHD, DTS-HD MA works in a core+extension configuration so players that do not support it can extract the DTS core audio. DTS-HD MA can either be downmixed to an analogue format if supported by the player, or bitsreamed via HDMI 1.3* to a compatible receiver.
*TOSLINK or Coaxial S/PDIF cannot carry a DTS-HD MA signal because the S/PDIF standard was finalised long before lossless HD-Audio was envisaged (despite S/PDIF being theoretically able to cope with the bandwidth). HDMI 1.3 or higher is therefore the only way to pass Dolby TrueHD audio.
