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fegger e82e7853d1 feat(app): adaptive quality, frame rate capping, and tighter VBV
Three changes to make the stream survive constrained links:

Adaptive quality: the sender pipeline now tracks the PLI rate from
the receiver. Every 5 seconds it evaluates: >0.5 PLI/s means the
link is saturated (the receiver is dropping frames), so the CRF
increases by 2 (lower quality, fewer bits) and the encoder restarts
with a keyframe. <0.1 PLI/s means the link is stable, so the CRF
decreases by 1 (better quality) and the encoder probes upward.
Clamped to [user CRF, user CRF + 10] so quality never degrades
below what the link can handle, and never exceeds what the user
asked for. The adaptation is logged to stderr for visibility.

Frame rate capping (--fps N): throttles the capture loop to N
frames per second (0 = no cap; monitor rate). At 15fps instead of
60fps, the bandwidth requirement drops 4x at the same quality
level. Desktop content is still smooth at 15-20fps.

Tighter VBV: one frame period of buffer instead of two. A two-frame
buffer lets a keyframe spike to twice the target rate in one burst,
which overflows any constrained hop (Wi-Fi hotspot, slow switch)
and cascades into PLI storms. One frame period keeps bursts
within what the link can absorb in real time.
2026-09-09 13:00:03 +02:00

42 lines
1.2 KiB
C++

#pragma once
#include <cstdint>
#include <optional>
#include <string_view>
#include <variant>
namespace sc {
struct SendCommand {
std::string_view target = "monitor"; // monitor, window
std::string_view peer_address; // optional; empty means auto-discover
int bitrate_kbps = 4000; // VBV max bitrate
int crf = 22; // constant rate factor (quality)
int fps = 0; // 0 = no cap (capture rate)
};
struct ReceiveCommand {
std::string_view peer_address; // optional, informational
int local_rtp_port = 5004;
int signaling_port = 5005;
bool fullscreen = false;
bool software_decode = false; // --swdecode disables the hardware probe
};
struct DiscoverCommand {
int timeout_seconds = 3;
};
struct WaybarCommand {
bool toggle = false; // toggle streaming instead of printing status
};
using Command = std::variant<SendCommand, ReceiveCommand, DiscoverCommand, WaybarCommand>;
// Parse command line arguments. Prints usage and returns std::nullopt on error.
// `argv` is `char const* const*` so both `main`'s `char**` and const arrays
// convert implicitly.
std::optional<Command> parse_cli(int argc, const char* const argv[]);
} // namespace sc