YTUHD

YTUHD unlocks 1440p (2K) and 2160p (4K) options in the iOS YouTube app by expanding codec/media capability paths (VP9/AV1) that YouTube may otherwise gate by device, codec support, or app behavior.

What It Does

• Raises VP9/AV1 stream capability limits to 4K/60.
• Preserves 1440p/2160p VP9 and AV1 formats during format filtering.
• Routes VP9/AV1 decoding to a compatible path depending on device and YouTube version.
• Hooks codec support checks so software decode paths can be used correctly.

Compatibility

• iOS 11+

Decoder Paths

VP9

• As of YouTube 20.47.3, the built-in software VP9 decoder (HAMVPXVideoDecoder) was removed.
• YTUHD provides YTUHDVPXVideoDecoder (libvpx-backed) and replaces the original HAMVPXVideoDecoder on app versions that still have it.
• On devices with hardware VP9 decode support, VideoToolbox hardware decode is used.
• On older devices, VP9 can still run through software decode (YTUHDVPXVideoDecoder).

AV1

• As of YouTube 19.28.1, YouTube adds a software AV1 decoder path (HAMDav1dVideoDecoder) for devices that do not provide native AV1 hardware decode.
• If hardware AV1 decode is unavailable and YouTube does not provide HAMDav1dVideoDecoder, YTUHD provides YTUHDDav1dVideoDecoder (dav1d-backed).
• YTUHDDav1dVideoDecoder replaces the original HAMDav1dVideoDecoder on app versions that have it.
• Apply film grain and decode thread controls are forwarded into the dav1d config.

Server ABR

YTUHD can run with server-driven ABR disabled so format filtering is handled by the client ABR hooks.

• This mode is intended as a fallback/compatibility path.
• Client-ABR-only behavior is reliable only on iOS 14+ and YouTube versions that include PoToken (Proof of Origin) implementation.
• On older environments or app builds without PoToken support, server ABR should remain enabled.

Settings (In-App)

These options are shown in the YTUHD section inside YouTube settings:

• Use VP9/AV1: Enables the codec capability path used by YTUHD. Restart the app after changing.
• VP9 for all: Keeps VP9 across all resolutions. If off, non-4K VP9/AV1 streams are filtered out.
• Disable server ABR: Forces the client ABR path. Keep this off unless you need compatibility fallback behavior.
• Use AV1 (dav1d): Shows only when hardware AV1 is unavailable.
• Apply film grain: Shows with Use AV1 (dav1d) and controls AV1 grain synthesis.
• Decode threads: Software decode thread count (default: 2).
• Skip loop filter, Loop filter optimization, Row threading: VP9 software decode tuning options.

Sideloading Notes

Sideloaded apps often lose private entitlements required for hardware VP9 decode, so software decode will be used instead (higher battery cost).

YTUHD uses libundirect. For sideload builds, use this command to build the tweak with the trimmed down version of libundirect:

make SIDELOAD=1

As package:

make package SIDELOAD=1

Using TrollStore can help preserve entitlements for sideloaded YouTube builds.

Build

YTUHD requires Theos. Static libraries are built automatically on first make:

• VP9: libvpx
• AV1: dav1d

Install build tools for dav1d first:

brew install meson ninja

Build:

make package

Rebuild third-party static libraries explicitly:

make libvpx   # vendor/libvpx_ios/libvpx.a
make dav1d    # vendor/dav1d_ios/libdav1d.a

Updating Vendor Libraries

vendor/libvpx and vendor/dav1d are git submodules.

To pull newer upstream revisions:

git submodule update --remote

Then rebuild the static libraries:

make libvpx
make dav1d

Optional (recommended) sanity step before packaging:

make package

Licenses

Third-party notices are documented in NOTICES.