diff --git a/internal/adapters/audio/ffprobe_test.go b/internal/adapters/audio/ffprobe_test.go
new file mode 100644
index 0000000..609a84c
--- /dev/null
+++ b/internal/adapters/audio/ffprobe_test.go
@@ -0,0 +1,129 @@
+package audio_test
+
+import (
+	"context"
+	"errors"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"git.d-ma.be/mathias/tapir/internal/adapters/audio"
+	"git.d-ma.be/mathias/tapir/internal/uploads"
+)
+
+func TestParseProbe(t *testing.T) {
+	tests := []struct {
+		name string
+		json string
+		want uploads.Probe
+	}{
+		{
+			name: "audio-only m4a",
+			json: `{"streams":[{"codec_type":"audio","disposition":{"attached_pic":0}}],"format":{"duration":"2701.5"}}`,
+			want: uploads.Probe{Duration: 2701*time.Second + 500*time.Millisecond, HasAudio: true},
+		},
+		{
+			name: "mp4 with a real video stream",
+			json: `{"streams":[{"codec_type":"video","disposition":{"attached_pic":0}},{"codec_type":"audio"}],"format":{"duration":"240.0"}}`,
+			want: uploads.Probe{Duration: 240 * time.Second, HasAudio: true, HasVideo: true},
+		},
+		{
+			name: "mp3 whose only video stream is attached cover art is NOT video",
+			json: `{"streams":[{"codec_type":"audio"},{"codec_type":"video","disposition":{"attached_pic":1}}],"format":{"duration":"60"}}`,
+			want: uploads.Probe{Duration: 60 * time.Second, HasAudio: true},
+		},
+		{
+			name: "no streams at all",
+			json: `{"streams":[],"format":{"duration":"10"}}`,
+			want: uploads.Probe{Duration: 10 * time.Second},
+		},
+		{
+			name: "duration absent means zero, which Validate rejects as unreadable",
+			json: `{"streams":[{"codec_type":"audio"}],"format":{}}`,
+			want: uploads.Probe{HasAudio: true},
+		},
+		{
+			name: "duration reported as N/A means zero",
+			json: `{"streams":[{"codec_type":"audio"}],"format":{"duration":"N/A"}}`,
+			want: uploads.Probe{HasAudio: true},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := audio.ParseProbe([]byte(tt.json))
+
+			require.NoError(t, err)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}
+
+func TestParseProbe_GarbageIsAnError(t *testing.T) {
+	_, err := audio.ParseProbe([]byte("not json"))
+	assert.Error(t, err)
+}
+
+// stub writes an executable shell script standing in for ffprobe. This is a fake
+// at the process boundary: the real binary is not on every host (it is not on
+// koala), and what is under test is how Probe drives and interprets a process.
+func stub(t *testing.T, body string) string {
+	t.Helper()
+	p := filepath.Join(t.TempDir(), "ffprobe")
+	require.NoError(t, os.WriteFile(p, []byte("#!/bin/sh\n"+body+"\n"), 0o755))
+	return p
+}
+
+func TestFFprobeProbe_ParsesWhatTheProcessPrints(t *testing.T) {
+	bin := stub(t, `echo '{"streams":[{"codec_type":"audio"}],"format":{"duration":"90"}}'`)
+
+	got, err := (&audio.FFprobe{Bin: bin}).Probe(context.Background(), "/ignored")
+
+	require.NoError(t, err)
+	assert.Equal(t, uploads.Probe{Duration: 90 * time.Second, HasAudio: true}, got)
+}
+
+func TestFFprobeProbe_PassesTheFilePathAsTheLastArgument(t *testing.T) {
+	out := filepath.Join(t.TempDir(), "args")
+	bin := stub(t, `for a; do last="$a"; done; printf '%s' "$last" > `+out+`
+echo '{"streams":[{"codec_type":"audio"}],"format":{"duration":"1"}}'`)
+
+	_, err := (&audio.FFprobe{Bin: bin}).Probe(context.Background(), "/spool/upload-123")
+
+	require.NoError(t, err)
+	got, err := os.ReadFile(out)
+	require.NoError(t, err)
+	assert.Equal(t, "/spool/upload-123", string(got))
+}
+
+func TestFFprobeProbe_NonzeroExitMeansTheFileIsUnreadable(t *testing.T) {
+	bin := stub(t, `echo "Invalid data found when processing input" >&2; exit 1`)
+
+	_, err := (&audio.FFprobe{Bin: bin}).Probe(context.Background(), "/x")
+
+	assert.ErrorIs(t, err, uploads.ErrUnreadable)
+}
+
+func TestFFprobeProbe_MissingBinaryIsOurFaultNotAnUnreadableFile(t *testing.T) {
+	_, err := (&audio.FFprobe{Bin: filepath.Join(t.TempDir(), "no-such-ffprobe")}).Probe(context.Background(), "/x")
+
+	require.Error(t, err)
+	assert.False(t, errors.Is(err, uploads.ErrUnreadable),
+		"a missing ffprobe must not be reported to the user as their file being bad")
+}
+
+func TestFFprobeProbe_StopsWhenTheContextIsCancelled(t *testing.T) {
+	bin := stub(t, `sleep 30`)
+	ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+	defer cancel()
+
+	start := time.Now()
+	_, err := (&audio.FFprobe{Bin: bin}).Probe(ctx, "/x")
+
+	require.Error(t, err)
+	assert.Less(t, time.Since(start), 5*time.Second)
+	assert.False(t, errors.Is(err, uploads.ErrUnreadable), "a timeout is not a verdict on the file")
+}