1 kHz Sine Tone
A pure 1000 Hz sine tone, 3 seconds, 16-bit 44.1 kHz mono — a clean reference signal for level metering, spectrum analysis, and waveform rendering.
Audio
Audio test files usually arrive as someone's music clip. These are engineered. The silence sets are 440 Hz tones with precisely documented leading and trailing silence — 1, 3, and 5 seconds — so you can point an auto-trim tool at them and check the result against exact timestamps. The reference set covers pure sine tones at 440 Hz and 1 kHz, a 20 Hz–20 kHz sweep, and white and pink noise, each with documented sample rate, bit depth, and duration. Every file is short to stay within budget and ships as WAV for lossless fidelity. Use them to test trimming, level metering, spectrum analysis, waveform rendering, and format handling against known, reproducible signals.
Reference Tones
220 Hz Sine Tone
A pure 220 Hz sine tone, 3 seconds, 16-bit 44.1 kHz mono — a clean reference signal for level metering, spectrum analysis, and waveform rendering.
440 Hz Sine Tone (A4)
A pure 440 Hz sine tone, 3 seconds, 16-bit 44.1 kHz mono — a clean reference signal for level metering, spectrum analysis, and waveform rendering.
Frequency Sweep 20 Hz–20 kHz
A 5-second linear sweep from 20 Hz to 20 kHz across the full audible range — for testing frequency response, spectrograms, and playback fidelity.
Pink Noise
Three seconds of pink noise with a 1/f power spectrum — the standard reference for loudness and room-calibration testing.
White Noise
Three seconds of white noise with a flat power spectrum — a reference for testing noise handling, gating, and spectral tools.
Codec Set
AAC — ADTS
The clip as raw AAC in an ADTS stream — the codec behind most streaming and mobile audio. For testing AAC decoders and remux into MP4.
AC-3 — Dolby Digital
The clip as AC-3 (Dolby Digital) — the multichannel codec used in DVD/broadcast. Rendered here in stereo; for testing AC-3 decoding and conversion.
ALAC — Apple Lossless
The clip as Apple Lossless (ALAC) in an M4A container — lossless, unlike the AAC M4A twin. For testing ALAC decoding and lossless conversion.
AMR — Narrowband Speech
The clip resampled to 8 kHz mono and encoded as AMR narrowband — the telephony/voice-note codec. For testing AMR decoding and speech-codec conversion.
FLAC — Lossless
The clip as FLAC — free lossless audio compression. Byte-for-byte recoverable to the source PCM; for testing lossless decoders and conversion.
M4A — AAC (MP4)
The clip as AAC in an MP4/M4A container (faststart) — Apple's default audio container. For testing M4A parsing and MP4 audio conversion.
M4R — iPhone Ringtone
The clip as an M4R iPhone ringtone — AAC in an MP4 container with the ringtone extension. For testing that a converter maps M4R↔M4A correctly.
MP3 — CBR 192 kbps
The source clip as constant-bitrate MP3 (LAME, 192 kbps) — the most universally supported lossy audio format. For testing MP3 decoders, players, and conversion.
MP3 — VBR (V2)
The same clip as variable-bitrate MP3 (LAME V2) — for testing VBR handling, seeking, and duration estimation against the CBR twin.
OGG — Vorbis
The clip as Ogg Vorbis — a royalty-free lossy codec. Browser-playable; for testing Vorbis decoding and Ogg conversion.
Opus
The clip as Opus — the modern low-latency codec used by WebRTC and streaming. Browser-playable; for testing Opus decoding and conversion.
WAV — Codec-Set Source
The lossless PCM WAV source for the audio conversion set — the same 3-second tone every other codec in this group is encoded from. Use it as the reference when diffing encoders.
WMA — Windows Media Audio
The clip as Windows Media Audio (WMA v2) in an ASF container — Microsoft's lossy codec. For testing WMA decoding and conversion to open formats.
Container Formats
AIFF — 1 kHz Sine Tone
A pure 1 kHz sine tone stored as AIFF — Apple's big-endian 16-bit PCM container, 3 seconds, 44.1 kHz mono. A clean reference for testing AIFF decoders and WAV↔AIFF conversion.
AIFF — 440 Hz Sine Tone
A pure 440 Hz sine tone stored as AIFF — Apple's big-endian 16-bit PCM container, 3 seconds, 44.1 kHz mono. A clean reference for testing AIFF decoders and WAV↔AIFF conversion.
AU — 1 kHz Sine Tone
A pure 1 kHz sine tone stored as a Sun/NeXT AU file — big-endian 16-bit PCM, 3 seconds, 44.1 kHz mono. A compact reference for AU decoding and format conversion.
AU — 440 Hz Sine Tone
A pure 440 Hz sine tone stored as a Sun/NeXT AU file — big-endian 16-bit PCM, 3 seconds, 44.1 kHz mono. A compact reference for AU decoding and format conversion.
Silence Trim Set
Leading Silence 1s — 440 Hz Tone
A 440 Hz tone preceded by exactly 1 second of digital silence. A direct fixture for auto-trim tools — the tone should start at 1.000s.
Leading Silence 3s — 440 Hz Tone
A 440 Hz tone preceded by exactly 3 seconds of digital silence. A direct fixture for auto-trim tools — the tone should start at 3.000s.
Leading Silence 5s — 440 Hz Tone
A 440 Hz tone preceded by exactly 5 seconds of digital silence. A direct fixture for auto-trim tools — the tone should start at 5.000s.
Trailing Silence 1s — 440 Hz Tone
A 440 Hz tone followed by exactly 1 second of digital silence. The tone should end at 2.0s — a direct fixture for testing trailing-silence trimming.
Trailing Silence 3s — 440 Hz Tone
A 440 Hz tone followed by exactly 3 seconds of digital silence. The tone should end at 2.0s — a direct fixture for testing trailing-silence trimming.
Trailing Silence 5s — 440 Hz Tone
A 440 Hz tone followed by exactly 5 seconds of digital silence. The tone should end at 2.0s — a direct fixture for testing trailing-silence trimming.