If you want to convert an audio file from one format to another, like a WAV or M4A to MP3, there are two basic options. The first option is that your browser will be able to handle the conversion by processing the file internally, without uploading it. In that case, it may require you to download a program or library, and you might need to allow some storage access for the converted file.
Alternatively, you can upload the file into a third-party service’s browser interface and have them convert it using their own internal software. Either way, you’ll need to ensure that whatever service handles the conversion actually supports the input format and output format that you wish to use.
File Eligibility
When you start looking at converting files, keep in mind that while certain formats (WAV, FLAC, M4A, AAC, OGG) can be converted into MP3 via Sodaphonic, other protected files (like music purchased from Apple Music, Amazon Music, etc.) cannot be converted, according to CloudConvert. You should also consider that these services may not support every codec or protected file that they’re listed as supporting, especially older versions of purchased Protected AAC songs.
You should also consider whether you are legally allowed to do this. If you’ve obtained the audio file through purchase, streaming, etc., that alone doesn’t give you permission to reproduce it. You need to own the copyright or be authorized or legally permitted to do so, even if you don’t share it. That includes conversion; but please remember that if you’ve downloaded it from a pirate site, that’s different.
In terms of the process, there are two primary workflows that browsers provide for handling conversions: local processing within the browser itself, or converting on a server elsewhere by uploading the file.
Local Processing Within the Browser
One browser-supported audio converter is Sodaphonic, which allows you to select an audio file directly from your device. When you choose an audio file, Sodaphonic provides the option of setting your desired MP3 output format, including channel selection (stereo or mono), before starting the conversion. After you click “Flip It” (or similar), the conversion will begin inside the browser, and you’ll see a progress bar indicating how much has been completed. While the browser will be converting your file, no data from your file will be uploaded to any remote server. Instead, the processing engine that converts the audio is downloaded from a CDN on the first conversion.
Sodaphonic doesn’t ask for an account, though you can sign in with Facebook, Twitter, Google or GitHub to enable additional features. Once the conversion is done, it will automatically save your finished MP3 file to your device, allowing you to download it immediately.
Sodaphonic says that your source file will stay in the browser during conversion, and the finished file is saved to your device. Saving to an account, sharing, and transcription are separate features that upload audio.
Upload-Based Conversion
The Online Audio Converter is another method to convert between file formats. Unlike Sodaphonic, Online Audio Converter requires you to first upload the original file to its web interface. Once it has been uploaded, you can choose the desired format — here, MP3 — as well as the desired output quality, which will determine the file size and compression level of the resulting file. Other controls include the bitrate, frequency and channel settings, but note that these vary per platform and may not match what Audacity offers.
Like Sodaphonic, you’ll have to decide on your settings beforehand, though you can make changes and convert again later. Just remember that re-encoding an MP3 can reduce quality. Once the conversion is done, you’ll need to download the output file to your computer; Online Audio Converter says it automatically deletes files from its servers a few hours after you’re done working with them. Just bear in mind that you should only use these services if you trust them.
Music and Speech Starting Settings
There are various recommendations for how to encode an audio file. For example, the manual provided with Audacity recommends encoding music files at 170–210 kbps VBR stereo, whereas speech files can be encoded at 96 kbps CBR mono.
Other services like Sodaphonic suggest using stereo when encoding music, and mono when encoding a single voice. Again, these controls exist in most converters, but may not all appear exactly the same. In addition, Audacity’s MP3 export dialog box defaults to exporting the file at 44,100 Hz, but other programs such as browser-based converters may offer more flexibility depending on where they get their conversion algorithms from. In general, however, it’s worth noting that the intended player’s requirements should always take precedence over what the encoder offers.
In short, unless you have specific needs or preferences regarding playback, you should leave the sample rate as is. That said, the available controls vary quite a bit, so you may find yourself adjusting your choices based on what each service provides.
File-Size and Quality Tradeoffs
As mentioned earlier, MP3 is a lossy format, which means that information that was discarded in previous encodings cannot be recovered simply by re-encoding. In fact, converting a compressed audio file to an uncompressed format won’t improve its sound quality, and converting it back to MP3 can cause further quality loss.
Because of this, any audio data discarded during compression cannot be recovered from the compressed file. However, there is a practical solution. Simply create a new playback copy from the original audio file rather than converting it, then store both the original and the new MP3 file. This approach avoids unnecessary loss of information while still ensuring that both files remain available should you ever want to revisit them later.
Completion Checks
Once the audio file is converted, listening to the saved MP3 will complete the conversion. You should also play the file back within the player in which you plan to listen to the audio file. In addition to checking that the file is playable, you should also verify that the file meets the expectations of your playback system. For example, a higher quality audio file will result in a larger file, but it won’t necessarily improve the playback experience. Likewise, lower quality audio files will reduce the file size, but again, this may not impact playback negatively. A smaller MP3 file should still have the same playback duration as the original audio; if it ends early, check for trimming or an incomplete conversion.
Practical Recovery Steps
If the conversion fails, then you may be left with a problem. Fortunately, it’s usually fairly simple to solve. First, try listening to the saved MP3 to see if it works. If it doesn’t, then check your connection and restart the conversion process. Alternatively, try a shorter file or choose a different format altogether.