How We Measure APE Viewer’s Speed

From A New Picture To A Decoded Picture

The clock starts when the sharing PC has a new picture of the screen and stops when the viewer has decoded it, drawn it and handed it to Windows to show. In between: hardware video encoding, encryption, sending the packets, receiving and putting them back together, and hardware decoding.

The sharing PC stamps each picture with the time it was ready. The viewer compares that with its own clock when the picture is shown. On one PC both use the same Windows clock. Between two PCs, APE Viewer works out the difference between their clocks from its own pings.

What It Leaves Out

• The network. Both ends ran on one PC and talked over 127.0.0.1, so no packet crossed a cable or Wi-Fi.
• Grabbing the screen. A built-in test picture stood in for the screen, so the clock starts when the picture is ready, not when a game draws it.
• Your monitor. The time your display takes to refresh and switch its pixels isn’t counted.
• Your mouse and keyboard. The trip from your input to the sharing PC, and the time the game takes to react and draw, aren’t part of this number.

Over A Real Network

Your connection adds its own delay on top. For the picture alone, add the one-way trip to your PC. From pressing a key to seeing the result, add your full ping (the round trip) to the sharing PC, plus the time the game takes to draw. The stream’s stats show your ping, so you can add it up for your own setup.

The PC

• Windows 11 Pro with an NVIDIA GeForce RTX 3080 and 2560 × 1440 monitors.
• APE Viewer 0.6.0 sharing a 2560 × 1440 test picture (color bars with a moving square), and a second copy of APE Viewer on the same PC watching it without a window: it decodes and draws each picture off screen.
• Video encoded on the RTX 3080 with NVENC, using APE Viewer’s low-latency settings (fastest preset, low-latency tuning, no B-frames), and decoded on the same card.
• 60 Mbps of bandwidth and V-Sync off, which are the app’s defaults. Sound and clipboard sharing were off.
• Nothing else used the graphics card’s video encoder during the runs; we checked with NVIDIA’s own tools.

The Runs

For each codec and frame rate we ran 5 sessions of 12 seconds. Each second, the viewer prints its stats, including its running average of the latency; we skipped the first 3 readings of each session (connecting and the first full picture) and took the median of the rest. The figure in the table is the median of the 5 sessions, and the range shows the lowest and highest session.

Frame Rates And Your Monitor

The test picture changes at whatever frame rate the viewer asks for, so the 120 and 144 fps runs didn’t depend on the monitors’ refresh rate. On a real screen, APE Viewer gets a new picture from Windows each time the screen changes, so the stream can’t go faster than the sharing PC’s monitor refreshes: 144 fps needs a 144 Hz monitor, and 240 fps a 240 Hz one. The PC’s owner can also cap the frame rate in Hosting.

The rest of APE Viewer’s column on our comparison describes APE Viewer 0.6.0:

• Frame rate: choices of 30, 60, 90, 120, 144 and 240 fps, up to the sharing PC’s monitor refresh rate.
• Video: H.264 or HEVC. Hardware encoding with NVENC on NVIDIA graphics, and with the hardware encoder the graphics driver installs on AMD and Intel. Hardware decoding on the viewing PC; HEVC needs the HEVC Video Extensions from the Microsoft Store there.
• Bandwidth: 10 to 200 Mbps for a PC’s screens together (60 by default), and 5 to 150 Mbps for one screen from the stream toolbar.
• Controllers: Xbox-style controllers become virtual Xbox 360 controllers on the sharing PC, and the game’s rumble comes back. 1 on Free, up to 4 with the PC owner’s Premium. The sharing PC needs the free controller driver.
• Mouse for games: when a game hides and locks the pointer, the stream window locks your mouse too and sends raw movement. You can also keep it locked or free.
• Monitors: Free shows 1 screen at a time. Premium opens every screen at once, each in its own window or full screen on a display you choose.
• Sound: 48 kHz stereo, sent uncompressed, so there’s no audio codec delay.

In a stream, open Picture on the toolbar and turn on Show stats, or press Ctrl+Alt+Shift+S. The line under the toolbar shows latency, frames per second, Mbps, decode time, ping and lost frames. Your numbers will depend on your PCs, the game and your network.

Spotted a mistake? Email support@apeviewer.com.