Audio-only files

Audio-only files in their usual containers: M4A, FLAC, MP3, Ogg and WAV.

The files

7 files in snapshot 2026-11-02. Each one's full fact sheet and recipe: GET /v1/cases/{id}, no token needed.

• AAC in M4Aaudio-only/aac.m4a M4Astereo AAC at 48 kHz, 6 s, 98 kB Facts
• ALAC in M4Aaudio-only/alac.m4a M4Astereo ALAC at 48 kHz, 6 s, 150 kB Facts
• FLAC fileaudio-only/flac.flac FLACstereo FLAC at 48 kHz, 6 s, 107 kB Facts
• MP3 fileaudio-only/mp3.mp3 MP3stereo MP3 at 48 kHz, 6 s, 97 kB Facts
• Opus in Oggaudio-only/opus.opus Oggstereo Opus at 48 kHz, 6 s, 125 kB Facts
• 16-bit PCM in WAVaudio-only/pcm.wav WAVstereo 16-bit PCM at 48 kHz, 6 s, 1.2 MB Facts
• Vorbis in Oggaudio-only/vorbis.ogg Oggstereo Vorbis at 48 kHz, 6 s, 27 kB Facts

What's in every file

Every video carries its frame number and timecode, burned in at the top left, a frame code along the bottom that the checker reads, and a white flash in the first three frames of every second. The audio carries a tone with a 40 ms beep at the start of every second. So a test can tell which frame is on screen, whether any were dropped, and whether sound and picture line up.

How they were verified

Before publishing, every file was probed and decoded by FFmpeg 7.1.5-0+deb13u1 and GStreamer 1.26.2 (sidecar subtitle files are probed only), and every file with video was played through the testsrc checker, which reads the frame code to confirm frames, timing, orientation, aspect and colour.

Use them

# one file's facts
curl https://testsrc.com/v1/cases/audio-only/aac.m4a

# play every file in this category through your player and check what it showed
testsrc run --player libvlc audio-only/

See the API reference for tokens, quotas and snapshots.

Other baseline categories