What does HDMI passthrough mean?

HDMI passthrough refers to the direct transmission of audio data, rather than the decoding process. Specifically:

• Definition: When a device plays audio or video through the HDMI interface, the output end will directly transmit the undecoded original audio data to the receiving end. This transmission method is called HDMI passthrough.

Working principle: Taking Dolby AC3 format audio as an example, in the passthrough mode, the output end transmits the undecoded AC3 data instead of the decoded and converted PCM data.

• Advantages: Preserve original audio quality: The transparent transmission can retain the original audio encoding format, ensuring that the audio quality is not affected by the decoding process.

Compatibility: Users can use receiving devices that support specific audio formats, such as Dolby Atmos or DTS:X, without relying on the decoding capability of the output end.
Reduce transmission delay: The transparent transmission function helps reduce transmission delay and improve the synchronization effect of audio and video.

• Application scenarios: The HDMI transparent transmission function is widely used in home entertainment systems and professional audio equipment, such as TV boxes that use the transparent transmission function to directly transmit audio in Dolby AC3 format to TVs that support this format, achieving high-quality audio output.
• Notes: The implementation of the transparent transmission function requires both the output end and the receiving end to support the corresponding audio format. If either end does not support transparent transmission, the audio data will be processed according to the default decoding method of the device, which may result in a decline in audio quality. Therefore, when using the transparent transmission function, it is necessary to ensure device compatibility and audio format support.