Understanding the Compatibility of PCM and Dolby Atmos in Home Audio Systems
The question of whether Pulse Code Modulation (PCM) supports Dolby Atmos is a common one. To clarify, PCM is not inherently designed to support Dolby Atmos, as it is merely a method for digitally representing analog signals. However, Dolby Atmos audio can be transmitted using PCM as part of the audio signal, typically through HDMI or other digital interfaces.
Transmission and Playback of Dolby Atmos Content
In practical scenarios, Dolby Atmos content is delivered in formats that use PCM for the audio stream. This allows compatible devices to decode and play back the immersive sound experience that Dolby Atmos is known for. For proper playback of Dolby Atmos, you need compatible hardware like a receiver or soundbar that can decode the Atmos signal, regardless of whether it's transmitted as a bitstream or as PCM.
Technical Details of PCM and Dolby Atmos
PCM stands for Pulse Code Modulation, which is one way of digitally representing sampled analogue signals. It is the decoded and uncompressed form of most digital audio chains and systems right before the Digital-to-Analog Conversion (DAC). Whatever processing has occurred ultimately results in a PCM stream. A PCM stream can contain as many discrete channels as required, typically from 1 to 10.
Dolby Atmos is a lossy audio codec, just one of many available. After the signal has been demultiplexed (demuxed) from its source, it is decoded and processed before it becomes an uncompressed PCM stream, ready to be fed to the DAC. Most digital audio encoding and decoding schemes, even those that are uncompressed like CDDA, ultimately end up as PCM samples at the end of the audio processing chain.
Home Audio Systems and Dolby Atmos
When it comes to consumer home audio systems, the process for decoding Dolby Atmos via a TV soundbar or AVR is a bit more complex. The source device, whether it's a streaming device, Blu-ray player, or UHD player, must be set to send a bitstream output. When a device converts the audio to PCM, it must downmix it to a standard number of channels. The only standardized PCM channel configurations are 2.0, 5.1, and 7.1. This means that if you only have a 7.1 or lesser system with only speakers around, PCM may sound the same as the source regardless of the number of speakers present.
However, if you have more than 7.1 speakers around, you will not get all of the benefits of Dolby Atmos through PCM. Some systems can activate the Dolby Surround Upmixer to create overhead sounds, but these will not be the same as the content creator intended. All of the extra data needed to produce the real-time panning and overhead sounds can only get to the decoder by sending the original bitstream.
Conclusion
While PCM is not inherently compatible with Dolby Atmos, it can be used to transmit Dolby Atmos content. The key is in the hardware compatibility and your specific home audio system setup. For the best experience with Dolby Atmos, consider a system that supports it natively or has the capability to decode the original bitstream.