baijum/record-clips

Record Clips for Video Project

Record per-scene video clips for a TOML video project. Each clip is a short screen recording of one scene's interactions on the Android emulator or iOS Simulator.

Prerequisites

Android

• ADB at ~/Library/Android/sdk/platform-tools/adb
• A running emulator (verify with adb devices)
• App installed on emulator (run ./gradlew installDebug if needed)
• Onboarding already dismissed

iOS

• Xcode with xcrun simctl available
• A booted iOS Simulator (verify with xcrun simctl list devices booted)
• App installed on simulator
• Onboarding already dismissed

Recommended Workflow (Audio-First)

Before recording clips, generate the voiceover audio first so you know exactly how long each clip needs to be:

source ~/.secrets
python3 scripts/assemble_video.py <android.toml or ios.toml> --audio-only

This prints a table showing the required min_clip_duration for each scene. Record clips at least that long.

Recording Process (Android)

Step 1: Read the project

Parse the android.toml to get the scene list. For each scene, note:

• name -- what the scene shows
• video -- where to save the clip (under clips/android/)
• min_clip_duration -- minimum recording length (or use 30s default)
• recording_notes -- step-by-step instructions for what to do on screen during recording. Follow these precisely to avoid navigating away from the target screen or triggering unwanted intents. If recording_notes is absent, infer interactions from the narration text.

Step 2: Prepare the app

ADB=~/Library/Android/sdk/platform-tools/adb
$ADB shell am force-stop com.baijum.ukufretboard
sleep 1
$ADB shell am start -n com.baijum.ukufretboard/.MainActivity
sleep 3

Step 3: Record each scene

For each scene:

1. Read the scene's recording_notes field for explicit interaction instructions
2. Navigate to the correct screen state (use drawer + uiautomator)
3. Set up the initial state described in recording_notes
4. Start recording with the scene's min_clip_duration as the time limit
5. Perform the interactions listed in recording_notes (respect any "Do NOT" warnings)
6. Stop recording and pull the file

# Navigate to screen (use uiautomator to find coordinates)
$ADB shell input tap 80 200    # hamburger menu
sleep 1
$ADB shell uiautomator dump /sdcard/ui.xml 2>/dev/null
$ADB shell cat /sdcard/ui.xml | tr '>' '\n' | grep 'text="<ScreenName>"'
$ADB shell input tap <x> <y>
sleep 2

# Record clip
$ADB shell screenrecord --time-limit <min_clip_duration> --size 1080x2424 /sdcard/scene.mp4 &
PID=$!
sleep 2

# Perform interactions for this scene
# ...
sleep <remaining_time>

# Stop and pull
kill $PID 2>/dev/null
sleep 3
$ADB pull /sdcard/scene.mp4 <project_dir>/clips/android/<scene_file>.mp4
$ADB shell rm /sdcard/scene.mp4

Step 4: Validate all clips

After recording all clips, check that every one has a valid duration:

for clip in <project_dir>/clips/android/*.mp4; do
  dur=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$clip")
  echo "$(basename $clip): ${dur}s"
done

Any clip showing N/A is corrupt and must be re-recorded. Common causes:

• Recording was too short (under ~3s) -- the moov atom wasn't written
• Static screens with no pixel changes -- add a touch interaction to generate frames

Recording Process (iOS)

Step 1: Read the project

Parse the ios.toml to get the scene list. For each scene, note:

• name -- what the scene shows
• video -- where to save the clip (under clips/ios/)
• min_clip_duration -- minimum recording length (or use 30s default)
• recording_notes -- step-by-step instructions for iOS-specific interactions

Step 2: Prepare the app

SIM_UUID=$(xcrun simctl list devices booted -j | python3 -c "import sys,json; devs=json.load(sys.stdin)['devices']; print([d['udid'] for ds in devs.values() for d in ds if d['state']=='Booted'][0])")
xcrun simctl terminate $SIM_UUID com.baijum.ukufretboard.ios
sleep 1
xcrun simctl launch $SIM_UUID com.baijum.ukufretboard.ios
sleep 3

Step 3: Record each scene

# Start recording
xcrun simctl io $SIM_UUID recordVideo --codec=h264 /tmp/scene.mp4 &
PID=$!
sleep 2

# Perform interactions (navigate manually or via accessibility automation)
# ...
sleep <remaining_time>

# Stop and move
kill -INT $PID 2>/dev/null
sleep 3
mv /tmp/scene.mp4 <project_dir>/clips/ios/<scene_file>.mp4

Step 4: Validate all clips

for clip in <project_dir>/clips/ios/*.mp4; do
  dur=$(ffprobe -v error -show_entries format=duration -of csv=p=0 "$clip")
  echo "$(basename $clip): ${dur}s"
done

Navigation Reference (Android)

Use uiautomator dump for precise coordinates. See android-screenshot-capture for details.

Drawer items: Open drawer with input tap 80 200, then find items by text.

Collapsible sections: If a drawer section is collapsed, expand it first:

$ADB shell cat /sdcard/ui.xml | tr '>' '\n' | grep 'content-desc="Expand'

Below the fold: Scroll down in the drawer for Reference section items:

$ADB shell input swipe 400 1800 400 400 500

Settings: Tap the gear icon (top-right, not in drawer):

$ADB shell input tap 1007 200

Tips

• Follow recording_notes precisely -- These instructions prevent common errors like accidentally navigating away from the screen, tapping share buttons that launch intent pickers, or ending up on the home screen.
• Always record longer than needed -- the assembler pads clips with tpad if they're short, but clips that are too short (< 3s) may be corrupt.
• Add interaction to static screens -- Screens like the Tuner or Pitch Monitor at rest produce very few frames. Touch the screen or scroll slightly to ensure the recording is valid.
• Use --time-limit generously (Android) -- Set it to min_clip_duration + 5 for safety. You can always kill the recording early if the interactions finish sooner.
• Re-record individual scenes -- One of the key benefits of the TOML project system. Just re-record the one clip and re-run python3 scripts/assemble_video.py <toml-file>.
• Respect "Do NOT" warnings -- Some scenes warn against tapping specific buttons (e.g., share buttons that launch Android intent pickers). Ignoring these will navigate away from the app.