
Opus format is quite interesting. It is not just one codec, but a set of specialized codecs in one package. When it comes to regular codecs, the same algorithm is used to compress any audio content, and only the bitrate varies. In the case of Opus, everything works differently - the SILK algorithm is used to compress human speech, and the CELT algorithm is used for music. At the same time, both algorithms can be combined in one audio file. This allows you to combine the incompatible - a high compression ratio, low latency and high sound quality. Previously, you could only choose two of the three criteria. It became even more unique after the introduction of machine learning technologies. Now it uses generative adversarial network to improve the efficiency of compression of speech signals and recovery of lost packets.
1 Does it need converting?
Before we address the issue of converting to another format, let's see how widespread Opus is and how well it is supported by software and hardware.
Since this codec replaces Speex, it has received mass support in VoIP first of all. And I'm not just talking about specialized software like Linphone, but also voice chats in Discord and Teamspeek. It is used to compress voice in the WhatsApp messenger and even in the Sony PlayStation Network.
To transmit high quality music, it was first implemented in YouTube and Vimeo, and then in the specialized streaming service SoundCloud. Since we are talking about web services, it is worth mentioning that almost all modern browsers have long since added support for Opus.
What about operating systems and hardware platforms? Things are pretty good here, too. Microsoft was the first to implement Opus support in Windows 10, then Apple followed suit with full support in iOS 17 and macOS Sonoma 14. New media player models from Rockbox, iriver and Archos got Opus support even earlier.
As you can see, the word "new" is repeated throughout the list. Unfortunately, the Opus format is completely unknown to older operating systems and hardware players. This can be partially corrected by installing third-party software where possible. But, as you can understand, this is the main reason to convert Opus to another format, even with worse parameters.
2 What format is best to convert to?
Which of the popular formats should I choose as an alternative? If we consider sound quality as the main criterion, then Opus significantly surpasses the old Vorbis and MP3 codecs. Codecs with lossless compression are in a different class and are not an equivalent replacement. There is only one codec that provides comparable sound quality and has wide support - Advanced Audio Coding, or AAC for short. In its raw form it is not very convenient, so it is most often found in the MP4 container and has the M4A extension.

For IP telephony, the requirements are different, the primary concern is not sound quality, but packet loss tolerance and low latency. The closest competitor in this area is AMR-WB, which we wrote about recently. This format is not very popular due to high licensing fees. If you lower the bar of requirements, then the direct predecessor in the person of Speex becomes the main contender. However, the choice largely depends on the operating system and telecom software used.
3 Converting Opus to AAC on desktop
I choose Audio Converter Plus primarily because it doesn't have all the bells and whistles that marketers try to attract. But it always has the most up-to-date versions of codecs and its own high-quality engine for resampling and normalization on the fly. It is one of the first to receive support for new formats, and therefore it allowed converting Opus to MP3 back in 2012, when few people knew about it.

You can download the trial version of the converter for free from the link above on the official website. Once you've installed it, just launch the program to see the main window. Before you get started, I suggest opening the program settings and adjusting the performance. Never choose a number of conversion threads that's more than the number of cores in your processor. It's best to leave two cores free for system processes.
Step 2: Add Opus audio filesAfter opening the main interface of Opus to AAC conversion program, you will see the “Add Files” button on the toolbar. You can add the Opus audio files you want to convert one by one to the program, or select the “Add Folder” option to load multiple audio files into the program at the same time. Alternatively, you can simply drag and drop audio files into the main program window.
Step 3: Select the output formatThen you can click the "Output Format" arrow to open the drop-down menu , which will show all the supported formats, and you can select "AAC" as the output format.
Step 4: Customize the format settingsTo customize the output format, you can open the Codec Settings window and start adjusting audio parameters such as sample rate, channels, and audio bitrate. The bitrate will have to be selected a bit higher than the original Opus file. Never set a fixed sample rate value if you are converting several files in one pass. They may all have different parameters, which will inevitably lead to resampling and loss of audio quality. It is better to select the Auto option in the codec settings, since the AAC format supports almost any input parameters.
Step 5: Convert OPUS to M4AOnce you've added all the audio files and set all the parameters, just click the "Convert" button. This will start batch converting all Opus to AAC with the same settings. The progress window will show you any possible errors that occur during the conversion process, but you can review them when everything is ready.
4 Online conversion of Opus to AAC
Since we're talking about online services, I'd like to raise the issue of privacy again. In most cases, conversion is done on the server side and your file is available to the owners of the service. Of course, I'm not saying that someone is going to listen to your confidential conversations, but such a possibility exists, and neural networks are great at analyzing human speech. Uploading legally purchased songs to a third-party server is also a gray area - is this distribution and copyright infringement?
If you don't care about such issues, then several files can be converted for free on the Convertio website. As for audio conversion, the service uses ffmpeg, which relies on its own codec implementation and may be inferior to native implementations. In this regard, it is no different from a dozen similar services, the only difference will be in the free use limits.

Step 1: Go to the Convertio website and go to the Audio Converter section. In principle, you can start from the main page, but then you will have to scroll through more options to select the output format.
Step 2: Click Choose Files and select the Opus files you want to upload. Wait for the files to upload to the server, then click the "Convert all to" button and select the AAC format.
Step 3: Click the "Convert" button and wait for the Opus to AAC conversion to complete. After that, you will have 24 hours to download the finished files from the server.
5 Final words
In my opinion, the Opus format has a bright future. Most IT giants have long abandoned DRM and are attracted to open and free standards. Yes, now a huge park of obsolete equipment slows down the implementation of new codecs. Exactly the same situation has developed in video encoding with the AV1 codec. This is the only reason why it is necessary to convert Opus audio to proprietary AAC format, and sometimes even to lower quality MP3. But time will put everything in its place and in a few years we will already be discussing how to convert audio from a newer format to Opus.