Technology & formats
Mirroring runs your phone flat-out. Slides don’t.
Both put your phone's content on a big screen, but they work completely differently under the hood — and one of them keeps your battery working hard even while a slide just sits there.
6 min read
Jun 2026
Every claim sourced · 2 references
Halfway through the workshop your phone is hot and the battery's dropping fast. If you're mirroring your screen to the projector, that's not a surprise — mirroring is closer to live-streaming video than to "showing a slide," and it never stops working, even when nothing on screen is moving.
✕ The myth
"Mirroring or streaming slides — same thing for the battery."
Both show your screen on the TV, so they must cost about the same.
✓ The reality
They're built completely differently.
Mirroring captures, encodes and transmits video continuously. Slide-streaming sends one image, then goes essentially idle until you click.
The costly parts of a phone are well established: the display and connectivity are among the biggest power draws, and live video capture/streaming drains a battery quickly because the camera pipeline and video encoder run non-stop.1 During video streaming the display alone can account for roughly 15–22% of total power2 — and mirroring keeps the display, the encoder and the radio all pinned, even on a static slide. Sending a single slide, by contrast, is a brief burst followed by near-silence.
Where the energy actually goes
Mirroring's cost is duty cycle. To keep a live video feed going it must grab the framebuffer, compress it, and push a stream over Wi-Fi many times per second — whether the slide changed or not. Slide-streaming spends energy only at the transitions: encode one frame, send it, then let the encoder and radio rest. Over a 45-minute talk with a slide change every minute or two, that's the difference between running a marathon and taking a stroll with occasional sprints.
0%
Share of phone power the display alone can take during video streaming — one of several always-on costs in mirroring.
2
Encoder
Continuous video encoding is a documented fast-drain activity; mirroring runs it the whole time.
1
Bursty
Slide-streaming works only at each transition, then idles — far less duty cycle.
⚖ The honest bit — this is a mechanism, not a benchmark
We won't invent an "X% longer" number.
The direction is well-grounded: continuous capture-encode-transmit costs more than an occasional single-frame send, and display plus connectivity are top consumers.12 But the exact gap depends on your device, screen brightness, codec, and network — so we're not going to fabricate a precise figure. And honestly: if you're plugged into power, or your talk is ten minutes, none of this matters. Mirroring also has a real edge we won't hide — it can show anything on your phone, including live apps and video, which static slide-streaming can't.
Where SyncBy!App fits
SyncBy streams slides, not a live screen: it sends each slide as an image and then goes quiet, which is the low-duty-cycle side of this trade — gentler on the battery across a long session, and lighter on the network too. If what you need to show is genuinely live (a running app, a video, a real-time demo), that's a mirroring job, and we'll happily point you at a cable or a cast device instead. For slides, streaming is the calmer choice.
TL;DR
- Mirroring ≈ live video: continuous capture, encode and transmit — even on a still slide.
- Slide-streaming sends one image, then idles until the next click.
- Display and connectivity are top power draws; continuous encoding drains fast.12
- Honest caveat: direction is clear, exact numbers aren't — and mirroring wins when you must show live content.