An Android camcorder that films through a 1980s video chain.
Twelve tape formats, each modelled as a signal path rather than a colour grade with noise dropped on top.
MIT licence · Android 8.0+ · Kotlin + GLES 2.0
Download the APK · Try Tape Bench in your browser
- Record through the filter, live, with sound.
- Dub an existing video from your gallery through the same chain.
- Twelve formats, from a clean Hi8 to a tape that has been through 400 rentals.
- Period-correct audio — the microphone is band-limited, saturated, hissed and wobbled to match the machine. A linear VHS edge track sounds nothing like Hi-Fi AFM.
- Tape Bench, a browser tool for building your own format layer by layer.
Everything you see in the viewfinder is what lands in the file: the preview and the
encoder are drawn from the same filtered frame, in the same GL context. Output goes to
Movies/VHS-88/ as H.264 + AAC MP4.
| Format | Year | What makes it different | |
|---|---|---|---|
| 1 | VHS SP | 1983 | The reference. ~240 lines of luma, chroma smeared sideways, honest dot crawl. |
| 2 | VHS EP | 1987 | Six hours on one T-120. A third of the tape speed and it shows in everything. |
| 3 | Betamax | 1982 | Sony's better picture. Tighter luma, warmer, steadier transport. |
| 4 | VHS-C Cam | 1985 | Palmcorder with a single-chip CCD. Vertical smear off every highlight, date on every frame. |
| 5 | Video8 | 1987 | Metal particle tape. Cleaner, cooler, and the first one that sounded good. |
| 6 | Hi8 | 1989 | End-of-decade prosumer. 400 lines over S-video, so no dot crawl at all. |
| 7 | S-VHS | 1988 | Luma kept apart from chroma. Sharp, ringy, still tape. |
| 8 | U-matic | 1980 | Local news on a shoulder rig, shot on a pickup tube — highlights bloom and drag comet trails. |
| 9 | Tracking | 1986 | Nobody adjusted the tracking dial. Noise bands crawl up the picture and the colour drops out. |
| 10 | 3rd Gen | 1989 | Copy of a copy of a copy over an aerial lead. Ghosted, washed out, ringing on every edge. |
| 11 | Rental | 1986 | Be kind, rewind. Shed oxide, creased tape, a lifetime of other people's VCRs. |
| 12 | Security | 1984 | Lobby camera on a 24-hour time-lapse deck. Washed out, over-sharpened, always stamped. |
Three GL passes, in the order the signal actually travelled, all on GLES 2.0 at a fixed 640×480 working raster — the artefacts are tuned in pixels, so the look does not change with the output size.
 |
 |
| A frame as recorded — 640×480, filter baked in. | A 16:9 clip dubbed to tape, letterboxed into the 4:3 raster. |
| Effect | Why it is there |
|---|---|
| Vertical smear | An interline-transfer CCD leaking charge down the column under a specular highlight. The 80s camcorder signature nobody could avoid. |
| Comet trails | Pickup-tube lag: before CCDs, bright areas kept glowing for several frames. |
| Halation, softness, vignette | Cheap zoom lens and prism block. |
| Exposure / gamma / tint | Each machine's own colorimetry. |
| OSD burn-in | The character generator sat before the recording head, so the date stamp gets smeared and jittered by everything downstream — as it should. |
Done in YIQ, because that is where the losses happened.
| Effect | Why it is there |
|---|---|
| Luma bandwidth | VHS recorded luma as an FM carrier with roughly 3 MHz of usable bandwidth. |
| Chroma bandwidth and delay | Colour-under chroma had about 400 kHz — colour bleeds sideways for a dozen pixels and lands slightly to the right. |
| Pre-emphasis ringing | The recorder's boost that the player never quite undid: the bright fringe on the trailing edge of every hard transition. |
| Dot crawl | Chroma leaking into luma at the 3.58 MHz subcarrier, phase-flipped per line and per field, so it crawls. Absent on the S-video presets. |
| Cross-colour | Fine luma detail leaking the other way, into chroma: rainbows on striped shirts. |
| Time-base error | No consumer deck had a TBC. Per-line jitter plus a slow drift. |
| Head switching | The torn, noisy band at the bottom of every field. |
| Mistracking | A noise band that drifts up the picture and takes the colour with it. |
| Dropouts | Shed oxide — the head reads nothing for part of a line. |
| Tape noise | Luma grain that rises in the shadows; coarse, blocky chroma noise. |
| Interlace | Each field refreshes only every other line, so motion combs — driven off the previous frame, not faked. |
| RF ghost | Multipath, the giveaway of a dub made over an aerial lead. |
Barrel geometry, overscan (which is what hid the head-switching band in real life), scanlines, aperture-grille mask, halation bloom, vignette, screen glare, rounded corners.
The line structure and the phosphor mask are gated on output oversampling: rendering 480
scanlines into a 480-pixel-tall frame is not a CRT, it is a moiré pattern. They fade in
as the output gains the resolution to draw them — full strength in the viewfinder and at
High · 1280×960, off in a 1:1 Tape · 640×480 file, whose rows are the scanlines.
A linear VHS audio track ran past a fixed head at tape speed, so it lost everything above
~10 kHz (~5 kHz at EP), hissed, saturated early, and wobbled — wow at well under a hertz,
flutter at a few hertz. VhsAudioProcessor reproduces that with a modulated fractional
delay line, one-pole head response, soft saturation and level dropouts. The Hi-Fi AFM
presets (Video8, Hi8, S-VHS) get a genuinely good-sounding profile instead, in stereo.
A browser tool for building your own format — and for putting video through the filter
without an Android phone at all. Open tools/tape-bench.html:
one self-contained file, no build step, nothing to install, no server.
- The preview runs the app's own three shader stages, extracted from
VhsShaders.ktat build time, so the monitor cannot drift from what the camera records. - 23 layers in signal order — lens, tape, television. Add and remove them; order is physics, so it is fixed.
- Judge it against a built-in test pattern designed to expose every artefact at once, or load your own image or clip.
- Export the Kotlin and paste it into
VhsPreset.ALL, or export the filtered video.
Load a clip, choose a tape, press Export video. You get an MP4 with the picture filtered and the sound dragged through that machine's audio path. The file is one HTML document, so you can hand it to someone and they need nothing else.
What it needs: a recent Chrome or Edge for MP4 output. Firefox works but records WebM. Nothing is uploaded anywhere — the clip never leaves the machine it is opened on.
What to expect:
| Speed | Real time. A five minute clip takes five minutes. |
| Keep the tab visible | A hidden tab throttles rendering and drops frames. The tool warns you if that happened. |
| Shape | Everything lands on a 4:3 raster, because that is what these formats were. Fill crops to it, Letterbox keeps the whole frame and puts black either side. |
| Size | Set by the bitrate buttons. Saving from the hosted page is capped at 16 MB; the local file has no limit. |
| Audio | AAC is not available to browser recorders, so the sound is Opus in MP4. Players and ffmpeg are fine with it; if an editor objects, ffmpeg -i in.mp4 -c:v copy -c:a aac out.mp4. |
For long clips the phone app is the better tool — it writes H.264 + AAC and decodes as fast as the device allows rather than in real time.
Send them https://marcellomorettoni.github.io/vhs-filter/ — the tool runs straight
from the link, and it is rebuilt from tools/tape-bench.html on every push, so nobody
ends up holding a stale copy.
If you would rather hand over the file itself, tape-bench.html is attached to each
release, or use the download button on
tools/tape-bench.html. It is one document — mail it, drop it
in a chat, put it on a stick. It works offline and nothing it does leaves the machine.
Grab the APK from Releases, or build it:
echo "sdk.dir=/path/to/android-sdk" > local.properties
./gradlew :app:exportApk # signed release APK -> ./vhs-88.apk
adb install -r vhs-88.apkAndroid 8.0 (API 26) and up. Needs CAMERA, and RECORD_AUDIO for sound.
Release APKs are built by GitHub Actions straight from the tagged commit —
see .github/workflows/release.yml.
Android will not install an unsigned APK, so the release variant always gets a signing
config. By default it signs with the standard debug keystore, which is enough to
sideload. To sign with your own key, drop a keystore.properties next to
settings.gradle.kts:
storeFile=release.jks
storePassword=…
keyAlias=…
keyPassword=…That file and any *.jks / *.keystore are gitignored. A Play Store upload needs a key
you generate and keep — the debug key is not acceptable there.
The viewfinder is locked to landscape and the camera buffer is turned to match, which a few devices disagree about. There is a ROTATE button on the main rail: each press turns the picture a quarter turn, the fourth returns to automatic, and the choice is remembered. It applies to recordings, not just the viewfinder, and stays available while recording — if the framing is wrong mid-take you want to fix it, not lose the take.
Setup → Save debug report writes a text dump to Download/VHS-88/ and opens the
share sheet: device and build, display versus window rotation, every camera's
SENSOR_ORIENTATION, what CameraX asked for against what was applied, GL driver strings,
measured frame rate, and the SurfaceTexture transform matrix.
That last one matters more than it looks. An emulator hands back a matrix that swaps the axes, so it rotates the buffer itself, while a physical phone normally returns a plain vertical flip. Identical code lands 90° apart on the two — which is why a rotation bug can be invisible in an emulator and obvious on a real device.
vhs/ VhsShaders the three GLSL stages
VhsPreset the twelve machines, ~45 parameters each
VhsPipeline ping-pong buffers, one filtered frame per input frame
OsdRenderer the character generator, drawn at 320x240, sampled nearest
gl/ EglCore one context, many surfaces
GlUtil programs, FBOs, the fullscreen quad
render/ VhsRenderThread the GL thread: camera texture in, viewfinder and encoder out
camera/ CameraController CameraX preview feeding our SurfaceTexture
record/ VideoEncoderCore, AudioRecorderThread, VhsAudioProcessor, MuxerWrapper
media/ VideoFileProcessor, AudioFileTranscoder, MediaStoreSaver, DebugReport
ui/ MainActivity, CameraScreen, VhsPreviewView, Theme
tools/ tape-bench.html the format editor
Video timestamps come from the camera clock, zeroed on the first encoded frame. A
SurfaceTexture timestamp and System.nanoTime() are not guaranteed to share an epoch;
mixing them stretches the recorded duration.
The muxer holds samples until every track is registered. MediaMuxer will not accept a
sample before the audio encoder has registered, and the audio encoder cannot register
until the microphone produces its first buffer. Rather than discard the opening second of
the take, MuxerWrapper buffers and flushes.
- The tape stage always runs at 640×480.
High · 1280×960upscales in the CRT pass, so the picture keeps its 240-line character but the scanline structure is drawn sharply. - Imported video is letterboxed into the 4:3 raster by default. Turn off Setup → Letterbox imports to crop-to-fill instead.
- Front-camera capture is mirrored to match the viewfinder.
Built by Marcello Morettoni — https://github.com/MarcelloMorettoni/vhs-filter
Like the app? Buy me a coffee:
MIT — see LICENSE. Do what you like with it; a credit is welcome but not required.