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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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Autochop finds no hits or too many hits

If the status says analyzing transients, wait for analysis to finish and press [A] again. Raise sensitivity with [>] for softer attacks, or lower it with [<] for stronger ones. Check the active band with [B] and the trim start and end if expected hits are outside the selection. Autochop combines candidates less than 120 ms apart. It leaves existing chops unchanged when no candidates are available, rather than generating slices in silence or steady noise. Place markers manually when the source has no clear attacks. With more candidates than slots, Loudest selects the strongest following 500 ms windows, while First 10 keeps the earliest candidates. See Chopping And Slicing.

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Compressor edits do not apply

Open the sampler master compressor with [CTRL+K] or native [SHIFT+PAD 5]. Check that State is On, the ratio exceeds 1:1, and peaks exceed the threshold. Leave Makeup at 0 dB when comparing levels. See controls and signal order. An unavailable master output or failed control delivery leaves the displayed and saved settings unchanged. Restore the output in Settings if it is unavailable; retry after the control queue drains if it is busy. A disconnected output requires an audio-engine restart. A project load or new-project action rejected by the compressor control queue preserves the working project and playback; retry after recovering the output. Master bounces include compression, while channel exports keep their pre-master signal.

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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
On Linux with ALSA, playback and input capture resume after a buffer underrun or overrun while the device remains connected. An interruption can still produce an audible gap, and input samples lost during an overrun cannot be recovered. Repeated gaps indicate that the buffer or workload needs adjustment. If audio remains stopped, save your project and restart Meiji Sampler; check device selection and connections if the audio interface was disconnected.

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High latency

For finger drumming, check these in order:
  1. Use wired headphones or speakers. Bluetooth and external monitoring chains can add delay after the app has rendered the hit.
  2. Set Settings → Audio → Buffer Size to 128, exit Settings, and choose [Apply Now]. Try 64 if playback stays clean with your usual effects and recording workload. Move up one size if it crackles.
  3. Match Sample Rate to your audio interface. Lowering it to 44100 Hz increases the duration of a fixed-size buffer; it does not inherently improve latency.
  4. Check the sample’s leading silence and the channel’s Offset. A positive Offset deliberately delays every hit. See Effects And Parameters.
  5. Compare a loaded, unstretched one-shot with a pad that needs decoding, stretching, or stems. Wait for processing to finish before comparing repeated hits. A slow first hit and consistently late repeated hits point to different parts of the playback path.
  6. Compare the native macOS app or another supported terminal if response changes while the interface is busy.
The milliseconds beside Buffer Size describe one buffer, not measured key-to-speaker latency. At 48000 Hz, 64, 128, and 256 frames correspond to 1.33, 2.67, and 5.33 ms per buffer. See Audio Setup. If the cause is still unclear, use the latency diagnostic to separate input queue, preparation, and first-render delays. 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.
REV7 hardware has confirmed the live post-pitch BPM readout. Software tests additionally pin the outgoing BPM bytes and tempo-range slots. The physical range-indicator refresh still requires controller confirmation.
  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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Native musical MIDI is stopped or silent

Choose an explicit output and enable Output; pad notes follow successful assigned sample playback, including delayed decoding. A same-endpoint input/output is refused; duplicate stable identities cannot reconnect automatically. Clock Follower needs 24 stable intervals before joining phase (one minute at 1 BPM). Clock loss/invalid rate or overflow stops transport; output overflow needs a configuration toggle to rearm. After output replug, Stop/Play restarts Master. If the receiver sustains a note after cable loss, use its local panic: software can attempt releases but cannot deliver them across a disconnected cable. Physical Sync Out is refused until the actual controlling interface and electrical behavior are measured; MIDI Clock output does not validate the TS Sync socket.

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A selected stem is silent or reports a preparation error

Check the selected pad’s Stem value and status. Loading or Splitting means the background worker has not finished. If it fails, Meiji Sampler keeps the original sample but does not play it in place of the requested stem. Select All to hear the original. Stop cancels pending playback, so trigger the pad again after resolving the error. Existing validated cached audio can be used without the addon executable. Missing or damaged cached WAVs report a load error. See stem separation for setup and selection controls. On MPC Sample, a missing addon/model or checksum error requires a verified offline Stems Addon SD package and standalone restart. Existing completed stems can still load without the runtime. Worker disk loads and new inference validate source contents even when the path, audio format and length are unchanged. Externally replacing a file at the same path can leave already loaded original/stem audio in memory; restart Meiji Sampler to reload it. New output is normalized to the original frame coordinates so trim/chop positions stay valid. If memory pressure terminates inference, choose All or retry after reducing other memory use; physical performance is not yet qualified. Do not remove or export the SD card while the standalone session owns its addon image or background work.