RAON audio field guide
MP3 bitrate: choose quality with a file-size estimate
Bitrate controls how much data an MP3 uses each second. A higher value normally preserves more detail and creates a larger file; a lower value is easier to send but removes more information. The useful setting depends on the source, the listener, and the destination.
Short answer
- Speech and lessons: begin at 128 kbps. Try 96 kbps only when the size limit is strict.
- Music and rehearsal tracks: begin at 192 kbps. Use 256 kbps when cymbals, ambience, or stereo detail matter.
- Smallest practical file: trim silence before lowering bitrate. Removing unused time does not introduce codec damage.
- Important source: keep the WAV, FLAC, or original recording. Treat MP3 as the delivery copy.
Calculated MP3 file size by bitrate
Constant-bitrate size can be estimated before conversion: bitrate multiplied by duration, divided by eight. The values below use decimal megabytes and exclude the small amount of container and tag overhead. They are estimates, not measurements from a particular encoder.
| Bitrate | 1 minute | 10 minutes | 60 minutes | Practical starting use |
|---|---|---|---|---|
| 64 kbps | 0.48 MB | 4.8 MB | 28.8 MB | Rough voice reference |
| 96 kbps | 0.72 MB | 7.2 MB | 43.2 MB | Speech under a strict limit |
| 128 kbps | 0.96 MB | 9.6 MB | 57.6 MB | Lessons, interviews, spoken notes |
| 160 kbps | 1.20 MB | 12.0 MB | 72.0 MB | Voice with music or ambience |
| 192 kbps | 1.44 MB | 14.4 MB | 86.4 MB | General music and rehearsal tracks |
| 256 kbps | 1.92 MB | 19.2 MB | 115.2 MB | Music where detail matters |
| 320 kbps | 2.40 MB | 24.0 MB | 144.0 MB | Largest common MP3 setting |
Calculation used: kilobits per second × seconds ÷ 8. Actual downloads may differ slightly because of metadata, encoder behavior, and variable bitrate.
Voice, lessons, meetings, and interviews
Speech does not usually need the same bitrate as full-range stereo music. For a clear phone or microphone recording, 128 kbps is a reliable first export. It gives a one-hour estimate of about 57.6 MB, which is much easier to move than an uncompressed WAV. If an upload form has a 50 MB limit, first trim silence and unused sections. If the recording still exceeds the limit, compare a 96 kbps copy with the 128 kbps copy using headphones.
A higher bitrate cannot repair clipping, room echo, or background noise. It only preserves the existing signal more faithfully. When consonants sound watery or breaths become rough, move up one setting. When the result is only for note-taking and the words remain clear, the smaller copy may be the better practical choice.
Music and rehearsal audio
Music includes transients, stereo width, reverberation, and overlapping instruments. RAON Tools therefore uses 192 kbps as the practical middle starting point for music. For a piano lesson reference, ensemble rehearsal, or backing track sent to a phone, listen first to the beginning, the loudest passage, and a quiet ending. Those three sections reveal most obvious problems faster than listening only to the first ten seconds.
Choose 256 kbps when cymbals, sustained strings, room ambience, or stereo imaging become noticeably rough at 192 kbps. Choose 320 kbps only when the larger file is acceptable. It does not turn an MP3 source back into lossless audio. If the source is already MP3, another MP3 export can add a second generation of compression artifacts.
RAON listening check
- Keep one source. Start from the original WAV, FLAC, M4A, or recorder output rather than an MP3 that has already been exported several times.
- Create two candidates. For speech, compare 96 and 128 kbps. For music, compare 192 and 256 kbps.
- Match playback volume. A louder file can seem better even when the codec quality is not better.
- Check difficult moments. Listen to consonants and breaths for speech; listen to cymbals, applause, reverb tails, and dense chords for music.
- Choose the smaller passing file. If both copies meet the real listening need, the smaller one is easier to store and share.
What can change the result?
Bitrate is not the only variable. Mono speech can use data more efficiently than stereo music. A clean recording is easier to encode than a noisy room recording. Variable-bitrate encoders allocate data differently from constant-bitrate encoders. Browser-based conversion also depends on whether the browser can decode the source codec. For these reasons, use the table for planning and use a short listening comparison for the final decision.
In RAON Tools, open Audio Compressor to create a smaller MP3 copy, or use Audio Trimmer first when the recording contains long unused sections.
한국어 핵심 정리
음성 녹음은 128 kbps, 음악과 연습 음원은 192 kbps부터 시작하는 것이 무난합니다. 1시간 기준 예상 용량은 128 kbps가 약 57.6 MB, 192 kbps가 약 86.4 MB입니다. 실제 파일은 메타데이터와 인코더 방식에 따라 조금 달라질 수 있습니다.
용량을 줄여야 한다면 먼저 불필요한 무음 구간을 자르고, 음성은 96/128 kbps, 음악은 192/256 kbps 두 가지로 만들어 비교하세요. 원본 WAV나 FLAC은 보관하고 MP3는 공유용 복사본으로 사용하는 것이 안전합니다.