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Audio and playback problems

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No audio output

Check these in order:

1. the correct output device is selected in Settings
2. the correct Stereo Channels setting is selected if your interface has more than two outputs
3. the system output device itself works outside Meiji Sampler
4. the relevant channel is not muted
5. another channel is not soloed
6. preview playback works from the browser with [SPACE]

If browser preview works but pad playback does not, the issue is usually session state, assignment, or mixer state rather than audio initialization. If a pad plays a different section than expected, check whether a per-channel override is active — see Per-Channel Playback.

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Crackling or dropouts

Usually caused by buffer underruns. Try:

• increase buffer size
• reduce other audio-app load
• wait for background processing such as stems to finish
• simplify the active session

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High latency

Try:

• smaller buffer size
• 44100 Hz sample rate
• system default output device
• the native macOS app or a better-supported terminal

For DJ controller latency, use Settings → DJ → Buffer Size, which is separate from Settings → Audio → Buffer Size and defaults to 128 samples. Lower it to 64 samples for the tightest controller-to-speaker path; the change applies the next time DJ audio opens, so leave and re-enter the DJ tab. DJ mode uses that configured size for both system and controller hardware outputs. Every controller report, platter included, dispatches with its input snapshot. The deck then smooths platter velocity across roughly the last 5 ms of reports, which prevents the REV7’s encoder quantization from becoming audible pitch warble without delaying the gesture.

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A REV7 does not appear after powering on

You can power a DDJ-REV7 on or off while Meiji Sampler is open. When its MIDI controls are ready, the status says Pioneer DDJ-REV7 connected — decks are live. The controller can expose MIDI before its four-channel audio interface or optional high-resolution HID display, so controls may work while audio remains on system output and the display is blank.

1. Let the REV7 finish its boot sequence. Meiji Sampler automatically keeps checking for its delayed audio interface and HID display while the controller is connected.
2. Check the USB connection and close other DJ software that could hold the controller. Open Settings → MIDI Monitor to confirm that messages are arriving.
3. If the controller is connected but the status still says DJ audio → system output, wait up to 20 seconds for the audio interface to appear. Meiji Sampler retries every 250 ms, then opens the four-channel deck route at the REV7’s current native sample rate.
4. If the optional high-resolution display remains blank, controls and audio can still work. Its HID endpoint is retried independently from audio; when it appears, loaded decks replay their complete waveform and readout state.
5. If the controller remains invisible after those checks, disconnect and reconnect its USB cable, then power-cycle it. Restart Meiji Sampler only as the final escalation.

The runtime add/remove workflow is covered through virtual CoreMIDI devices. That is hardware-independent verification, not physical REV7 boot-timing certification. See DJ Mode for the connection and safe-disconnection workflow.

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Input works poorly

If recording or sampling from input is unstable:

• re-check input device selection
• verify the input channel
• confirm another app is not already monopolizing the device

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Time-stretch sounds wrong or takes too long

If a stretched loop sounds distorted or artifacts are audible:

• Extreme ratios (below 0.5x or above 2.0x) can produce artifacts on any material. Try a ratio closer to 1.0x if possible.
• Percussive material may lose transient sharpness when stretched significantly. Consider layering an unprocessed copy for attack.

If time-stretch is unexpectedly slow:

• The first stretch after an update regenerates the cache (the old cache is purged automatically when the engine version changes). Subsequent plays are instant.
• Very long samples take proportionally longer to process. The stretch runs in a background thread and does not block the UI.
• If transport shows warming synced audio…, a cued loop or scene is waiting for synced stretched audio before playback starts. This prevents the transport from starting early and playing that channel late.

If stretched audio sounds stale or mismatched:

• The cache validates against the expected length, channel count, and sample rate. Mismatched entries are regenerated automatically. If you still hear stale audio, clearing the stretch cache directory manually will force a full rebuild on next play.

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Pad stops unexpectedly when another pad plays

This is usually a choke group. Channels in the same choke group cut each other off — triggering one stops the others. Check:

1. open Channel Detail (Enter on the affected pad)
2. look at the Choke control
3. if it shows a group number, other channels in that group will stop this pad when they trigger

To fix, change or remove the choke group assignment with Left and Right.

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A DJ platter BPM is implausible or stale

On the optional high-resolution jog surface, Meiji Sampler sends the REV7 platter the deck’s current beatgrid BPM after pitch. The active ±8%, ±16%, or ±50% range determines how far the current fader position can move that value. It can change after background beatgrid analysis completes or after a beatgrid edit. Setting dj.hi_res_jog to false in config.json returns the REV7 to the Pioneer surface, which keeps the controller’s own idle display.

1. Wait for analyzing beatgrid… to finish before judging the readout.
2. If the tempo is exactly half or double what you expect, press ; or ' in DJ Mode to correct the grid tempo.
3. If the beats drift while the tempo is plausible, press , or . to move the beatgrid anchor.
4. Reload the track if analysis or an edit did not refresh the deck state.

See DJ Mode for how pitch and the grid contribute to the readout.

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A REV7 platter waveform ends before the audio

An older build was observed to reset its platter playhead near -01:00.4 on an approximately 96.6-second track while audio continued. Current builds send waveform uploads and the remaining-time countdown on the same display timeline, which is intended to correct that boundary. The post-fix physical result awaits hardware confirmation. If you reproduce the symptom after updating, reconnect the REV7 so its HID display service reinitializes, then report the result.

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DJ playback or scratching crackles

DJ keylock and vinyl manipulation support 44.1, 48, 88.2, and 96 kHz source/output combinations. You do not need to resample a bounce merely because its rate differs from the active output. If playback is clean but platter manipulation crackles:

1. close other realtime audio applications, raise Settings → DJ → Buffer Size to 256 samples, then leave and re-enter the DJ tab so the new size takes effect
2. test once with keylock off, then on, and note whether the symptom follows keylock or all vinyl motion
3. temporarily kill PerformFX with [SHIFT+K] to distinguish the deck path from an active effect
4. note the source rate, output rate, buffer size, jog mode, keylock state, pitch percentage, and whether hardware output was active

A repeatable crackle at a supported rate is not expected behavior. Keep those details with the affected bounce so the callback path can be reproduced without guessing.

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A DJ command says audio queue busy

Deck A: … not applied — audio queue busy means Meiji Sampler kept the screen and deck audio consistent by rejecting a command that could not enter the bounded real-time mailbox. The rejected action is not silently shown as successful.

1. Release the platter or key that is generating repeated movement, then try the command again.
2. If the message follows a controller reconnect or output-device change, let the DJ output finish rebuilding before retrying.
3. If ordinary single presses reproduce it, note the command, output device, buffer size, and whether hardware output was active.

A single transport, cue, pitch, keylock, nudge, sync, or scratch action should normally be admitted immediately. Repeated messages during ordinary use indicate a control-path fault rather than expected latency. If the status instead says DJ audio source cleanup failed — restart Meiji Sampler, stop the set and restart the app before continuing. That message reports a source-lifecycle invariant failure, not a recoverable rejected control action.

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DJ master recording is missing hardware mixer controls

This is expected when using a REV7 hardware mixer. DJ master recording captures the safety-limited post-PerformFX software master, which is the unity-gain sum of both post-PerformFX deck stems before the physical mixer. The physical EQ, channel faders, crossfader, microphone or auxiliary input, and hardware master processing are excluded. If you need those physical controls in a recording, capture the REV7’s physical master externally. For Meiji Sampler’s software-master recording workflow and [R] shortcut, see DJ Mode. For input-device recording, use [CTRL+R] instead.

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Linked pad does not fire

If a channel has a linked pad configured but the secondary trigger does not sound:

1. confirm the target channel has an assigned sample
2. confirm the link target is not the same channel as the source
3. open Channel Detail and verify the Link control shows the expected target

The linked pad will not fire if the target channel is empty or if the source pad itself has no sound to play.

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Linux-specific host issues

On Linux, if Auto is unstable, explicitly try:

• ALSA
• JACK if your system is already set up for it

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Related pages

• Audio Setup
• Settings
• Effects And Parameters
• Time-Stretch A Loop To Tempo
• DJ Mode