Step 1: Drop your Opus files using the button above or by deposit and leave.
Step 2: Click the 'Convert' button to start the conversion.
Step 3: Receive your converted M4A files.
Opus to M4A Conversion FAQ
What bitrate does the M4A file use?
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A lossy M4A is encoded at 192 kbps by default. The Audio Quality setting also offers 320 kbps for the best quality and 128 kbps for a smaller file. A lossless M4A (WAV, FLAC) ignores the bitrate and keeps every sample.
Is converting Opus to M4A a second round of lossy compression?
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Yes, and it is worth planning around. Both formats are lossy, so the M4A encoder is working from audio that has already been through one psychoacoustic pass, and its own decisions compound the first set. At 192 kbps or above the result is still transparent for most listening. If you have a lossless master anywhere, encoding the M4A from that instead avoids the double pass entirely. Opus scales from 6 kbps mono speech to 510 kbps stereo music in the same bitstream and switches modes automatically. An M4A holds AAC in most cases, or Apple Lossless (ALAC) when it came from a lossless rip.
Will going from Opus to M4A reduce my audio quality?
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If Opus is lossy and M4A is lossless (e.g. MP3 → WAV), the M4A file is no better than the Opus — you can't recover information that's already been thrown away. If Opus is lossless and M4A is lossy, expect the M4A codec to recompress; at 192 kbps this is transparent for most content.
Can I batch convert hundreds of Opus files to M4A?
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Several files in one job need a paid plan. Free use is one file per conversion, one conversion an hour. On a paid plan you can add several files to one job, then download each result on its own or all of them in one ZIP.
Will the M4A keep the same sample rate as Opus?
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By default yes (48 kHz Opus → 48 kHz M4A). If you need to downsample for compatibility (e.g. 96 kHz → 44.1 kHz for CD burning) the advanced sample-rate option does this with high-quality resampling.
Can I normalize loudness in the Opus to M4A step?
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Not in this step. The converter has no loudness setting and leaves the level as it is. To even out the volume, run the finished M4A through a Normalize tool on this site.
Will the M4A play on my car stereo / iPod / audiobook app?
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MP3 plays almost everywhere. AAC plays on Apple devices, most Android phones and Sonos. FLAC plays on Sonos and Android but not on older iPods, and WAV plays on nearly everything but makes large files. There are no device presets on this page, so choose the target format your player supports.
Is my Opus file private during conversion?
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Yes. Nobody listens to or shares the audio, which matters for personal audiobook libraries, and uploaded Opus files and their converted copies are deleted automatically about 24 hours after conversion.
How long does converting a 10-hour audiobook Opus to M4A take?
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It depends on the size and length of the file. Small documents and images are usually ready quickly. Long videos take the longest, because most video conversions re-encode every frame.
Why is the M4A file louder / quieter than the Opus source?
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The converter does not change the level: it has no gain or normalize setting. If you hear a difference, your player or media library is probably applying ReplayGain or its own volume levelling on playback; switch that off to hear the M4A as it is.
