Technical token design for NFT audio tokens.

The primary differentiator between non-fungible tokens and regular tokens is the underlying contract which specifies the token type. The choice of the contract is marked by several key features, which we will investigate in this technical review blog. Understanding the various designs of NFT tokens are important as they will become the underpinning of the NFT platform planned for the near future.

Traditionally tokens such as the OPT token which are used to play music on the Opus player, are specified as ERC-20. This works well for the case of democratizing music playback because it allows anybody who owns the token to play back music. Each individual token does not record the ownership of each purchase. However, as a NFT platform, it is important to uniquely record individual addresses in the blockchain that own the particular song on Opus. By doing so, we would enable the creation of a neutral platform where artists can release limited edition copies of songs that the holder of the token can unlock playback. It would also allow a trading platform to be developed where these tokens can be exchanged between listeners to listeners, creating hype that benefits both dedicated fans and artists alike — a mission that the Opus team has continually been striving towards.

In this regard the team has considered common NFT protocols such as the ERC-721, ERC-1155, and the upcoming token specified in EIP-2309. These standards define the functionality that we can include in our upcoming platform. The 721 token has the traditional API of ERC-20 tokens such as transfer(), balanceOf(), however it makes modifications such that these functions take a unique _tokenId. This uniquely differentiates each holder of each token and would allow the team to create unique tokens for every individual copy of every individual song for each artist. The ability to view the owner’s address also allows us to create exclusivity in the Opus player, which would be key to differentiating us from competing NFT platforms such as OpenSea which allow uncontrolled access of potentially copyrighted songs. Continuing from the common 721 standard, the ERC-1155 token is a continued development of ERC-721, with the ability to create atomic swaps and semi-fungible tokens, such as mini currencies. Furthermore, there is research on EIP-2309 which allows bulk minting of tokens.

After debate within the Opus team, we are favoring the traditional ERC-721 token for the current plan for a beta version of the NFT marketplace and player. We want to get the product out to you guys to test it out as fast as possible, and as a music platform, our token functionality are not as demanding as those of gaming companies. Work has begun on drafting and testing the underlying framework, be sure to check back here for regular updates on our research and development.

If you have any ideas or suggestions on functionality you would like to see in the product do let us know at, we would love to hear from you.

If you want to try the opus streaming platform yourself, start now by registering yourself here: (designated for artists) or here: (designated for listeners).


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Opus Foundation

Opus is a open-source decentralized music sharing platform with demo based on Ethereum and IPFS.