Documentation Index
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NuvioTV gives you granular control over both subtitle rendering and audio output. Subtitle settings live in PlaybackSubtitleSettings.kt and are backed by the subtitleStyle object inside PlayerSettings. Audio settings live in PlaybackAudioSettings.kt. Both sections are accessible in Settings → Playback in Advanced mode; Essential mode surfaces a minimal subset for quick setup.
Subtitle Settings
Preferred Subtitle Language
Essential + Advanced. Selects the language NuvioTV tries to activate automatically when a stream loads. The value is a BCP-47 language code or the special string "none" to disable subtitles by default.Set via viewModel.setSubtitlePreferredLanguage(language). Displayed using AVAILABLE_SUBTITLE_LANGUAGES sorted by display name.Secondary Subtitle Language
Advanced only. A fallback language used when the preferred language track is not available. Set via viewModel.setSubtitleSecondaryLanguage(language).Forced Subtitles
Essential + Advanced. When useForcedSubtitles is enabled, only tracks flagged as forced (typically foreign-language segments) are shown automatically. Useful for watching content where subtitles appear only for non-primary-language dialogue.Show Only Preferred Languages
Advanced only. When enabled (subtitleStyle.showOnlyPreferredLanguages), the subtitle selector in the player filters out tracks that do not match the preferred or secondary language. Useful for content with many subtitle tracks.Subtitle Startup Mode
Advanced only. Controls which subtitle tracks are loaded and active when a stream starts. The AddonSubtitleStartupMode enum values are surfaced as a single-choice dialog:// Values from AddonSubtitleStartupMode, displayed in PlaybackSubtitleSettings
subtitleStartupModeLabel(playerSettings.addonSubtitleStartupMode)
Subtitle Size
Advanced only. A percentage slider from 50% to 200% in steps of 10. Stored as subtitleStyle.size. Displayed in the player using the active renderer.SliderSettingsItem(
minValue = 50,
maxValue = 200,
step = 10,
value = playerSettings.subtitleStyle.size
)
Subtitle Vertical Offset
Advanced only. Moves subtitles up or down relative to their default position. Range: −20 to +50, step 1. Stored as subtitleStyle.verticalOffset.Subtitle Style: Colors, Bold, and Outline
Advanced only. These settings control the visual appearance of subtitle text:| Setting | Type | Description |
|---|
subtitleStyle.textColor | Color (ARGB) | Foreground text color; supports transparency via alpha slider |
subtitleStyle.backgroundColor | Color (ARGB) | Box background behind text; Transparent is a valid option |
subtitleStyle.bold | Boolean | Renders subtitle text in bold weight |
subtitleStyle.outlineEnabled | Boolean | Enables a colored outline around text characters |
subtitleStyle.outlineColor | Color (ARGB) | Color of the outline when enabled |
libass Subtitle Renderer
Advanced only.libass is strongly recommended for anime content or any .ass/.ssa subtitle files. These formats use complex per-line positioning, karaoke effects, and custom fonts that the platform’s built-in subtitle renderer does not support correctly. Enable libass whenever subtitles appear misaligned or unstyled.
useLibass enables the native libass renderer, which is bundled with NuvioTV (not a system dependency). When enabled, a render type must also be selected:LibassRenderType | Description |
|---|
OVERLAY_OPEN_GL | Renders subtitles via an OpenGL overlay; best performance on modern hardware |
OVERLAY_CANVAS | Renders subtitles via a Canvas overlay; more compatible but may be slower |
EFFECTS_OPEN_GL | OpenGL-based effects renderer; supports advanced ASS effects and animations |
EFFECTS_CANVAS | Canvas-based effects renderer; broader device compatibility for effects |
CUES | Standard platform cue renderer via libass; most compatible fallback |
viewModel.setUseLibass(enabled)
viewModel.setLibassRenderType(renderType)
Subtitle Timing Offset
Player UI (both modes). A per-session subtitle delay can be adjusted directly from the player’s subtitle side panel (SubtitleStyleSidePanel). This is a runtime offset and is not persisted to PlayerSettings unless the user saves it. The underlying delay configuration is managed by SubtitleDelayConfig.Audio Settings
Preferred Audio Language
Essential + Advanced. Selects the audio track language NuvioTV activates at stream start. The field accepts:
- A BCP-47 language code (e.g.,
"en", "ja")
AudioLanguageOption.DEFAULT — use the stream’s default trackAudioLanguageOption.DEVICE — match the device localeAudioLanguageOption.ORIGINAL — prefer the original production language
Set via viewModel.setPreferredAudioLanguage(language).Secondary Audio Language
Advanced only. Fallback language when the preferred audio track is unavailable. Set via viewModel.setSecondaryPreferredAudioLanguage(language).Decoder Priority
Essential + Advanced. Controls whether NuvioTV prefers the device’s hardware decoder or ExoPlayer’s software decoder. The value is an integer index:| Value | Label |
|---|
0 | Device only (hardware decoder required; falls back to no audio if unavailable) |
1 | Prefer device (hardware first, then software) |
2 | Prefer app (software first, then hardware) |
viewModel.setDecoderPriority(priority). Note: Force optical passthrough is disabled when decoder priority is 0.Skip Silence
Advanced only. ExoPlayer engine only. When skipSilence is true, ExoPlayer automatically trims periods of silence from the audio timeline. Useful for podcasts or talk content. Not available when MPV is the active engine.Audio Downmix
Advanced only. ExoPlayer engine only. downmixEnabled forces multi-channel audio to be mixed down to a configurable channel count. When enabled:
- Output channels (
AudioOutputChannels): sets the target channel layout (e.g., Stereo, 5.1).
- Maintain original audio on downmix (
maintainOriginalAudioOnDownmix): preserves the original loudness level rather than normalizing after downmix.
Tunneling
Advanced only. ExoPlayer engine only. tunnelingEnabled enables Android TV’s tunneled playback path. Tunneling bypasses the audio framework and routes PCM/compressed audio directly to the output device, which can improve A/V sync accuracy and enable hardware-accelerated decode on certain SoCs. Requires device support.Force Optical Passthrough
Advanced only. When forceOpticalPassthrough is true, NuvioTV forces bitstream passthrough over S/PDIF optical output. Only effective when decoder priority is not set to Device only (decoderPriority != 0).Dolby Vision P7 Fallback Profile
Advanced only. ExoPlayer engine only. The Dv7HandlingMode enum controls how Dolby Vision Profile 7 streams are processed on devices that do not have a DV7 display pipeline:| Mode | Description |
|---|
AUTO | App decides based on device capabilities |
HDR10_BASE_LAYER | Decodes only the HDR10 base layer |
DV81_LIBDOVI | Converts to DV 8.1 using libdovi |
STRIP_DV | Strips the enhancement layer entirely |
OFF | No special handling; pass DV7 to the decoder as-is |
dv5ToDv81Enabled converts DV5 streams to DV 8.1, and dv7ToDv81PreserveMappingEnabled preserves the color mapping during that conversion.MPV Hardware Decode Mode
Advanced only. MPV engine only. When the MPV engine is active, MpvHardwareDecodeMode controls the hardware acceleration method MPV uses. This setting is only meaningful when internalPlayerEngine is MVP_PLAYER or AUTO.Audio Delay
Player UI (both modes). An audio delay offset can be adjusted at runtime from the player controls via AudioDelayMediaSource and GainAudioProcessor. This offset is session-scoped. When rememberAudioDelayPerDevice is true (Advanced), the delay value is persisted per output device so it is automatically re-applied on the same TV or audio receiver.Audio Output Route Detection
AudioOutputRouteDetector monitors the active audio output route (built-in speakers, HDMI, optical, Bluetooth) and can surface this information in diagnostics. This is used internally by the player to decide whether passthrough is viable.Essential Mode Surface
In Essential mode, EssentialPlaybackSettingsContent shows a Subtitles and Audio group with the following rows:
- Preferred subtitle language (opens
LanguageSelectionDialog with a None option)
- Use forced subtitles toggle
- Preferred audio language (opens
LanguageSelectionDialog with Default, Device, and Original options)
- Decoder priority (opens
DecoderPriorityDialog)
All other subtitle and audio settings on this page are hidden until the user switches to Advanced mode.
Advanced Mode Surface
In Advanced mode, PlaybackSettingsSections renders the full Subtitles and Audio & Video collapsible sections within PlaybackSettingsScreen. Both sections are collapsed by default and can be expanded independently. The player also exposes a SubtitleStyleSidePanel for live subtitle style adjustment without leaving playback.