What is Dolby TrueHD?
Dolby TrueHD is a lossless audio codec used primarily in Blu-ray and high-bitrate home-theater distribution. Decoding reconstructs the encoded PCM audio without lossy compression loss.
Dolby TrueHD specifications
| Property | Capability |
|---|---|
| Compression | Lossless |
| Sample rates | 44.1 kHz to 192 kHz |
| Word length | Up to 24-bit |
| Blu-ray multichannel | Up to 8 channels at 24-bit/96 kHz; up to 6 channels at 24-bit/192 kHz |
| Maximum Blu-ray bitrate | Up to 18 Mbps |
TrueHD and MLP
Dolby TrueHD developed from Meridian Lossless Packing (MLP) technology and uses lossless predictive/entropy coding techniques to reduce PCM data rate without throwing audio information away.
TrueHD and Atmos
On Ultra HD Blu-ray and other premium delivery, Atmos information can be carried alongside a TrueHD-based bed/stream structure. A receiver showing “Dolby TrueHD” is describing the codec layer; “Atmos” describes the immersive presentation layer when present.
Where it appears
FFmpeg recognizes raw TrueHD elementary streams and TrueHD also appears inside Blu-ray transport streams and Matroska remuxes. The raw stream extension .thd is less common for ordinary users than containerized delivery.