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api: h.264 video stream (#876)

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## Link to GitHub Issue or related Pull Request, if one exists
fixes #875

## Description of change
Adds `-apistream`, an optional HTTP video stream of the mirrored screen.
It listens on the API port +2.

Two endpoints, sharing the same `screen`, `fps` and `q` parameters:

    /stream.mjpg    JPEG frames, for clients with no container support
/stream.h264 H.264 annex-b, for an app driving MediaCodec or
VideoToolbox itself

One encoder per connection, fed by a per-screen pump that always hands
over the newest frame, so a slow reader drops frames instead of building
a backlog. `capture.get_jpg` behaviour is unchanged.

Additional documentation for developers:
https://github.com/spice2x/spice2x.github.io/wiki/Video-Stream

## Testing
This commit is contained in:
bicarus
2026-08-19 03:10:02 -07:00
committed by GitHub
parent 7c50fcc79e
commit 0934cce225
18 changed files with 1089 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/spice2x/api/stream_server.cpp
+427
View File
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#include <winsock2.h>
#include <ws2tcpip.h>
#include "stream_server.h"
#include <algorithm>
#include <cctype>
#include <chrono>
#include <map>
#include <string>
#include <thread>
#include <vector>
#include "capture_pump.h"
#include "hooks/graphics/graphics.h"
#include "stream_format.h"
#include "util/logging.h"
#include "util/utils.h"
namespace api {
namespace {
struct HttpRequest {
std::string method;
std::string path;
std::map<std::string, std::string> query;
};
bool send_all(SOCKET socket, const void *data, size_t size) {
auto cursor = reinterpret_cast<const char *>(data);
size_t remaining = size;
while (remaining > 0) {
const int sent = send(socket, cursor, static_cast<int>(remaining), 0);
if (sent <= 0) {
return false;
}
cursor += sent;
remaining -= static_cast<size_t>(sent);
}
return true;
}
bool send_all(SOCKET socket, const std::string &text) {
return send_all(socket, text.data(), text.size());
}
std::string url_decode(const std::string &input) {
std::string out;
out.reserve(input.size());
for (size_t i = 0; i < input.size(); i++) {
if (input[i] == '+') {
out.push_back(' ');
} else if (input[i] == '%' && i + 2 < input.size()
&& isxdigit(static_cast<unsigned char>(input[i + 1]))
&& isxdigit(static_cast<unsigned char>(input[i + 2]))) {
out.push_back(static_cast<char>(
std::stoi(input.substr(i + 1, 2), nullptr, 16)));
i += 2;
} else {
out.push_back(input[i]);
}
}
return out;
}
void parse_query(const std::string &query, HttpRequest &request) {
size_t pos = 0;
while (pos < query.size()) {
auto end = query.find('&', pos);
if (end == std::string::npos) {
end = query.size();
}
const auto pair = query.substr(pos, end - pos);
const auto split = pair.find('=');
if (split != std::string::npos && split > 0) {
request.query[url_decode(pair.substr(0, split))] =
url_decode(pair.substr(split + 1));
}
pos = end + 1;
}
}
// reads the request head only; anything oversized or malformed is refused
bool read_request(SOCKET socket, size_t size_limit, HttpRequest &request) {
std::string head;
char buffer[1024];
while (head.find("\r\n\r\n") == std::string::npos) {
if (head.size() >= size_limit) {
return false;
}
// read no further than the limit, so the head cannot overshoot it
const size_t budget = std::min(sizeof(buffer), size_limit - head.size());
const int received = recv(socket, buffer, static_cast<int>(budget), 0);
if (received <= 0) {
return false;
}
head.append(buffer, static_cast<size_t>(received));
}
const auto line_end = head.find("\r\n");
const auto line = head.substr(0, line_end);
const auto method_end = line.find(' ');
if (method_end == std::string::npos) {
return false;
}
const auto target_end = line.find(' ', method_end + 1);
if (target_end == std::string::npos) {
return false;
}
request.method = line.substr(0, method_end);
auto target = line.substr(method_end + 1, target_end - method_end - 1);
const auto query_start = target.find('?');
if (query_start != std::string::npos) {
parse_query(target.substr(query_start + 1), request);
target = target.substr(0, query_start);
}
request.path = url_decode(target);
return true;
}
int query_int(const HttpRequest &request, const std::string &name, int fallback,
int min, int max) {
const auto pos = request.query.find(name);
if (pos == request.query.end()) {
return fallback;
}
try {
return std::clamp(std::stoi(pos->second), min, max);
} catch (const std::exception &) {
return fallback;
}
}
void send_error(SOCKET socket, const char *status) {
const std::string response =
std::string("HTTP/1.0 ") + status + "\r\n"
"Content-Length: 0\r\n"
"Connection: close\r\n"
"\r\n";
send_all(socket, response);
}
}
StreamServer::StreamServer(unsigned short port)
: port(port)
{
if (!this->open_listener()) {
// the stream was asked for explicitly, so say plainly that it is not there
log_warning("api::stream",
"the video stream is not available on port {}", this->port);
return;
}
this->running = true;
this->acceptor = std::thread([this] {
this->accept_worker();
});
// deliberately not logging a full URL; local IPs would leak into shared logs
log_info("api::stream", "video stream is listening on port: {}", this->port);
log_warning("api::stream",
"the video stream is unauthenticated - anyone who can reach port {} can watch "
"the game screen", this->port);
}
bool StreamServer::open_listener() {
WSADATA wsa_data;
const int error = WSAStartup(MAKEWORD(2, 2), &wsa_data);
if (error != 0) {
log_warning("api::stream", "WSAStartup() returned {}", error);
return false;
}
this->wsa_started = true;
this->listener = socket(AF_INET, SOCK_STREAM, 0);
if (this->listener == INVALID_SOCKET) {
log_warning("api::stream", "could not create listener socket: {}",
get_last_error_string());
return false;
}
int opt_enable = 1;
if (setsockopt(this->listener, SOL_SOCKET, SO_REUSEADDR,
reinterpret_cast<const char *>(&opt_enable), sizeof(int)) == -1) {
log_warning("api::stream", "could not set socket option SO_REUSEADDR: {}",
get_last_error_string());
}
sockaddr_in server_address {};
server_address.sin_family = AF_INET;
server_address.sin_port = htons(this->port);
server_address.sin_addr.s_addr = INADDR_ANY;
if (bind(this->listener, (sockaddr *) &server_address, sizeof(sockaddr)) == -1) {
log_warning("api::stream", "could not bind socket on port {}: {}",
this->port, get_last_error_string());
closesocket(this->listener);
this->listener = INVALID_SOCKET;
return false;
}
if (listen(this->listener, server_backlog) == -1) {
log_warning("api::stream", "could not listen on port {}: {}",
this->port, get_last_error_string());
closesocket(this->listener);
this->listener = INVALID_SOCKET;
return false;
}
return true;
}
StreamServer::~StreamServer() {
this->running = false;
if (this->listener != INVALID_SOCKET) {
closesocket(this->listener);
this->listener = INVALID_SOCKET;
}
// drops the client threads out of their blocking send/recv
{
std::lock_guard<std::mutex> lock(this->clients_m);
for (auto &client : this->clients) {
if (client.socket != INVALID_SOCKET) {
::shutdown(client.socket, SD_BOTH);
}
}
}
if (this->acceptor.joinable()) {
this->acceptor.join();
}
// joining is what guarantees no client thread outlives this object
for (auto &client : this->clients) {
if (client.thread.joinable()) {
client.thread.join();
}
}
if (this->wsa_started) {
WSACleanup();
}
}
void StreamServer::accept_worker() {
while (this->running) {
sockaddr_in client_address {};
int client_address_size = sizeof(sockaddr_in);
const SOCKET client = accept(
this->listener, (sockaddr *) &client_address, &client_address_size);
if (client == INVALID_SOCKET) {
// on shutdown the listener is closed under us; otherwise do not spin
if (this->running) {
std::this_thread::sleep_for(std::chrono::milliseconds(10));
}
continue;
}
if (!this->running) {
closesocket(client);
break;
}
char address_data[INET_ADDRSTRLEN] {};
inet_ntop(AF_INET, &client_address.sin_addr, address_data, INET_ADDRSTRLEN);
std::string address(address_data);
// every client costs an encode and real bandwidth, so the cap protects the game
int slot = -1;
{
std::lock_guard<std::mutex> lock(this->clients_m);
for (size_t i = 0; i < this->clients.size(); i++) {
if (!this->clients[i].active) {
this->clients[i].active = true;
this->clients[i].socket = client;
slot = static_cast<int>(i);
break;
}
}
}
if (slot < 0) {
log_warning("api::stream", "client limit of {} hit", client_limit);
send_error(client, "503 Service Unavailable");
closesocket(client);
continue;
}
// this thread is the only one that touches the thread objects, so the slot's
// previous occupant gets reaped here rather than being detached
if (this->clients[slot].thread.joinable()) {
this->clients[slot].thread.join();
}
this->clients[slot].thread = std::thread([this, slot, client, address] {
this->client_worker(slot, client, address);
});
}
}
void StreamServer::client_worker(int slot, SOCKET socket, std::string address) {
DWORD timeout = request_timeout_ms;
setsockopt(socket, SOL_SOCKET, SO_RCVTIMEO,
reinterpret_cast<const char *>(&timeout), sizeof(timeout));
timeout = send_timeout_ms;
setsockopt(socket, SOL_SOCKET, SO_SNDTIMEO,
reinterpret_cast<const char *>(&timeout), sizeof(timeout));
int opt_enable = 1;
setsockopt(socket, IPPROTO_TCP, TCP_NODELAY,
reinterpret_cast<const char *>(&opt_enable), sizeof(int));
// whatever sits in the send buffer is already stale, and the default holds about a
// third of a second of H.264 because the bitrate is so low. keeping it small makes a
// slow reader block the sender, which then skips to the newest frame instead of
// handing over a backlog
int send_buffer = send_buffer_bytes;
setsockopt(socket, SOL_SOCKET, SO_SNDBUF,
reinterpret_cast<const char *>(&send_buffer), sizeof(send_buffer));
HttpRequest request;
if (read_request(socket, request_size_limit, request)) {
if (request.method != "GET") {
send_error(socket, "405 Method Not Allowed");
} else {
const int fps = query_int(request, "fps", 30, 1, fps_limit);
const int quality = query_int(request, "q", 70, 1, 100);
auto writer = make_stream_writer(request.path, quality, fps);
if (!writer) {
send_error(socket, "404 Not Found");
} else {
// screen 1 is the subscreen in every game that has one; single-screen games
// only ever register screen 0, so resolve the default against what exists
int screen = query_int(request, "screen", -1, 0,
static_cast<int>(GRAPHICS_CAPTURE_SCREEN_NO) - 1);
if (screen < 0) {
std::vector<int> screens;
graphics_screens_get(screens);
screen = std::find(screens.begin(), screens.end(), 1) != screens.end()
? 1 : 0;
}
if (!capture_pump::claim_screen(screen)) {
log_warning("api::stream",
"screen {} is already being streamed, refusing {}",
screen, address);
send_error(socket, "503 Service Unavailable");
} else {
log_info("api::stream",
"client connected: {} ({}, screen={}, fps={}, quality={})",
address, request.path, screen, fps, quality);
const std::string header =
"HTTP/1.0 200 OK\r\n"
"Connection: close\r\n"
"Cache-Control: no-store, no-cache, must-revalidate\r\n"
"Pragma: no-cache\r\n"
"Content-Type: " + writer->content_type() + "\r\n"
"\r\n";
const StreamSend stream_send = [socket](const void *data, size_t size) {
return send_all(socket, data, size);
};
if (send_all(socket, header) && writer->begin(stream_send)) {
const auto interval = std::chrono::microseconds(1000000 / fps);
while (this->running) {
const auto started = std::chrono::steady_clock::now();
capture_pump::Frame frame;
const bool ok = capture_pump::capture_direct(
screen, frame.pixels, 1,
&frame.timestamp, &frame.width, &frame.height);
if (ok && frame.pixels
&& !writer->write(stream_send, frame)) {
break;
}
// a failed capture still paces, or a stalled game spins this
std::this_thread::sleep_until(started + interval);
}
}
capture_pump::release_screen(screen);
log_info("api::stream", "client disconnected: {}", address);
}
}
}
}
{
std::lock_guard<std::mutex> lock(this->clients_m);
this->clients[slot].socket = INVALID_SOCKET;
this->clients[slot].active = false;
}
closesocket(socket);
}
}