Abstract: The present disclosure provides a preparation method of manganese hydroxide, including subjecting a coarse manganese metal powder and water to a reaction under temperature-rising condition to obtain a manganese hydroxide slurry; oxidizing the manganese hydroxide slurry to obtain high-purity trimanganese tetraoxide; reducing the high-purity trimanganese tetraoxide to obtain high-purity manganese monoxide, allowing the manganese hydroxide slurry and carbon dioxide to have a reaction to obtain high-purity manganese carbonate; roasting the high-purity manganese carbonate to obtain the high-purity manganese monoxide. In the present disclosure, the preparation method maintains a purity advantage of electrolytic manganese metal products, can reduce energy consumption, achieve safe and clean production, and avoid environmental problems.

Abstract: An audio and video transmission system includes a multimedia device. The multimedia device includes a high-definition multimedia interface (HDMI) receiver, a first transfer circuit, and a first universal serial bus type C (USB-C) interface. The first transfer circuit is configured to transfer a first audio signal output by an audio channel pin of the HDMI receiver into a second audio signal in a universal serial bus (USB) interface format. The first USB-C interface is configured to transmit the second audio signal. The HDMI audio channel pin is an audio return channel (ARC) pin or an enhanced ARC pin.

Abstract: An audio and video transmission system includes a multimedia device. The multimedia device includes a high-definition multimedia interface (HDMI) receiver, a first transfer circuit, and a first universal serial bus type C (USB-C) interface. The first transfer circuit is configured to transfer a first audio signal output by an audio channel pin of the HDMI receiver into a second audio signal in a universal serial bus (USB) interface format. The first USB-C interface is configured to transmit the second audio signal. The HDMI audio channel pin is an audio return channel (ARC) pin or an enhanced ARC pin.