Compare MP3, AAC, and Opus with audio you know
Choose an audio file or a video with an audio track. This tool encodes the full track in each format so you can hear actual compressed output, not a predicted quality score. Switching tracks keeps the same playback position.
It automatically creates MP3, AAC, and Opus versions at 64, 128, and 160 kbps. Select 256 or 320 kbps to encode those versions on demand. Listen, inspect the waveform and spectrogram, compare integrated LUFS and estimated true peak, or download the encoded files.
MP3 128 kbps vs 320 kbps
Higher MP3 bitrates use more data per second and may preserve more detail. How audible that difference is depends on the recording, your headphones or speakers, and your listening environment.
Switch between 128 and 320 kbps at the same point. Listen to cymbals, vocal consonants, reverb tails, and busy passages. Select the 320 kbps option to encode it first.
AAC vs MP3 at the same bitrate
Both use lossy compression, but they use different encoders and do not necessarily sound the same at 128 kbps. Both 128 kbps versions are included in the initial comparison.
Compare the sound and resulting file sizes using your own music, voice recording, or other material.
Opus vs AAC at the same bitrate
The Opus encoder uses variable bitrate (VBR), so its actual average bitrate may differ from the selected target. File sizes can also differ between formats.
Switch between AAC 128 kbps and Opus 128 kbps, for example, and listen for differences in music, speech, or sound effects.
Hear the difference signal
Difference playback subtracts the encoded audio from the decoded original after aligning their timing to the sample. It is unavailable if the automatic alignment is unreliable.
The result can include phase changes and encoding noise. It does not isolate only sounds that were “removed” by compression.
What do the waveform and spectrogram show?
The waveform shows how amplitude changes over time; it cannot establish sound quality by itself. The spectrogram shows frequency content over time. At lower bitrates, high frequencies or fine time details may look different. Use the graphs alongside listening.
Does this reproduce YouTube, Instagram, or TikTok audio?
Streaming and social platforms may re-encode uploaded audio. This tool lets you compare compression formats and bitrates, but it does not reproduce any platform’s actual processing or guarantee how your post will sound.
Labels such as “YouTube reference,” “Instagram reference,” and “TikTok reference” are comparison presets in this tool only. Check your published content on the platform for the final result.
Encoding and measurement details
Playback and analysis use 48 kHz stereo. MP3 and AAC downloads use 44.1 kHz when the input is 44.1 kHz; otherwise they use 48 kHz. Opus downloads use 48 kHz. The table shows the source or downloaded file’s sample rate.
MP3 uses libmp3lame at constant bitrate (CBR). AAC uses FFmpeg’s AAC encoder with a target bitrate. Opus uses libopus at variable bitrate (VBR). Actual average bitrates and file sizes can vary.
“Original” is decoded PCM. A lossy input remains lossy after decoding. Switching playback tracks uses a 10 ms crossfade with no automatic loudness matching. Difference playback aligns encoded audio to the sample.
Integrated LUFS measures overall loudness. True peak is an estimate based on 4× oversampling. A red marker shows the highest estimated peak above 0 dBTP. LUFS cannot be calculated for silence or audio shorter than 0.4 seconds. Neither measurement alone determines sound quality.
Your files stay on your device
Encoding, analysis, and playback happen in your browser. Your audio, video, and file name are not uploaded to our server. Closing the page discards the loaded audio.
Frequently asked questions
Which sounds better: MP3, AAC, or Opus?
There is no universal winner. Results depend on the bitrate, encoder, source audio, and playback setup. Encode the same source at the same target bitrate, then switch at the same playback position to judge for yourself.
Can I hear a difference between MP3 128 kbps and 320 kbps?
It depends on the recording, listener, and playback conditions. Compare the same passage repeatedly, especially cymbals, vocal consonants, and reverb. The 320 kbps option is encoded when you select it.
Will MP3, AAC, and Opus at 128 kbps have the same file size?
Not necessarily. Codec behavior, CBR versus VBR, and container overhead affect the final size. Check the actual sizes in the comparison table.
Can I use a video file?
Yes, if it contains an audio track in a supported format. This tool compares that audio track; it does not compare video quality. Video files can be up to 600 MB.
Does it work on a phone?
It requires a browser with WebAssembly, Web Audio, and Web Workers. Audio files can be up to 120 MB, videos up to 600 MB, and audio length up to 10 minutes. Long files may need more memory than your device has.
What does Difference playback contain?
It plays Original minus Encoded after timing alignment. You may hear phase changes and encoding noise as well as altered audio. It is disabled if alignment is uncertain, such as with silence or repetitive tones.