WIP: Add V4L2

src/airplaywindow.cpp

@@ -1,11 +1,22 @@
 #include "airplaywindow.h"
 #include <QApplication>
+#include <QCheckBox>
 #include <QDebug>
 #include <QHBoxLayout>
+#include <QLabel>
+#include <QMessageBox>
 #include <QPixmap>
 #include <QPushButton>
 #include <QVBoxLayout>
 
+// V4L2 includes
+#include <cstring>
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/videodev2.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
 // Include the rpiplay server functions
 extern "C" {
 int start_server_qt(const char *name);
@@ -17,12 +28,18 @@ std::function<void(uint8_t *, int, int)> qt_video_callback;
 
 AirPlayWindow::AirPlayWindow(QWidget *parent)
     : QMainWindow(parent), m_videoLabel(nullptr), m_statusLabel(nullptr),
-      m_serverThread(nullptr), m_serverRunning(false)
+      m_serverThread(nullptr), m_serverRunning(false), m_v4l2_fd(-1),
+      m_v4l2_width(0), m_v4l2_height(0), m_v4l2_enabled(false)
 {
     setupUI();
 
     // Setup video callback
     qt_video_callback = [this](uint8_t *data, int width, int height) {
+        // V4L2 output if enabled
+        if (m_v4l2_enabled) {
+            writeFrameToV4L2(data, width, height);
+        }
+
         QByteArray frameData((const char *)data, width * height * 3);
         QMetaObject::invokeMethod(this, "updateVideoFrame",
                                   Qt::QueuedConnection,
@@ -34,6 +51,7 @@ AirPlayWindow::AirPlayWindow(QWidget *parent)
 AirPlayWindow::~AirPlayWindow()
 {
     stopAirPlayServer();
+    closeV4L2();
     qt_video_callback = nullptr;
 }
 
@@ -63,6 +81,24 @@ void AirPlayWindow::setupUI()
 
     statusLayout->addWidget(m_statusLabel);
     statusLayout->addStretch();
+
+    // V4L2 controls
+    QCheckBox *v4l2CheckBox = new QCheckBox("Enable V4L2 Output");
+    connect(v4l2CheckBox, &QCheckBox::toggled, this, [this](bool enabled) {
+        m_v4l2_enabled = enabled;
+        if (!enabled) {
+            closeV4L2();
+        }
+        qDebug() << "V4L2 output" << (enabled ? "enabled" : "disabled");
+    });
+
+    QPushButton *testV4L2Btn = new QPushButton("Test V4L2");
+    testV4L2Btn->setToolTip("Test V4L2 loopback device availability");
+    connect(testV4L2Btn, &QPushButton::clicked, this,
+            [this]() { testV4L2Device(); });
+
+    statusLayout->addWidget(v4l2CheckBox);
+    statusLayout->addWidget(testV4L2Btn);
     statusLayout->addWidget(startBtn);
     statusLayout->addWidget(stopBtn);
 
@@ -153,3 +189,122 @@ void AirPlayServerThread::run()
     stop_server_qt();
     emit statusChanged(false);
 }
+
+// V4L2 Implementation
+void AirPlayWindow::initV4L2(int width, int height, const char *device)
+{
+    closeV4L2(); // Close previous device if any
+
+    m_v4l2_fd = open(device, O_WRONLY);
+    if (m_v4l2_fd < 0) {
+        qWarning("Failed to open V4L2 device %s: %s", device, strerror(errno));
+        QMessageBox::warning(
+            this, "V4L2 Error",
+            QString("Failed to open V4L2 device %1.\n"
+                    "Make sure v4l2loopback module is loaded:\n"
+                    "sudo modprobe v4l2loopback")
+                .arg(device));
+        return;
+    }
+
+    struct v4l2_format fmt;
+    memset(&fmt, 0, sizeof(fmt));
+    fmt.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+    fmt.fmt.pix.width = width;
+    fmt.fmt.pix.height = height;
+    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
+    fmt.fmt.pix.field = V4L2_FIELD_NONE;
+    fmt.fmt.pix.bytesperline = width * 3;
+    fmt.fmt.pix.sizeimage = (unsigned int)width * height * 3;
+
+    if (ioctl(m_v4l2_fd, VIDIOC_S_FMT, &fmt) < 0) {
+        qWarning("Failed to set V4L2 format: %s", strerror(errno));
+        ::close(m_v4l2_fd);
+        m_v4l2_fd = -1;
+        QMessageBox::warning(
+            this, "V4L2 Error",
+            "Failed to set V4L2 video format. Device may not support RGB24.");
+        return;
+    }
+
+    m_v4l2_width = width;
+    m_v4l2_height = height;
+    qDebug("V4L2 device %s initialized to %dx%d", device, width, height);
+}
+
+void AirPlayWindow::closeV4L2()
+{
+    if (m_v4l2_fd >= 0) {
+        ::close(m_v4l2_fd);
+        m_v4l2_fd = -1;
+        qDebug("V4L2 device closed.");
+    }
+}
+
+void AirPlayWindow::writeFrameToV4L2(uint8_t *data, int width, int height)
+{
+    // Check if V4L2 device needs to be initialized or re-initialized
+    if (m_v4l2_fd < 0 || m_v4l2_width != width || m_v4l2_height != height) {
+        initV4L2(width, height, "/dev/video0"); // Use your v4l2loopback device
+    }
+
+    // Write frame to V4L2 device if it's open
+    if (m_v4l2_fd >= 0) {
+        ssize_t bytes_written =
+            write(m_v4l2_fd, data, (size_t)width * height * 3);
+        if (bytes_written < 0) {
+            qWarning("Failed to write frame to V4L2 device: %s",
+                     strerror(errno));
+            closeV4L2(); // Close on error to retry initialization
+        }
+    }
+}
+
+void AirPlayWindow::testV4L2Device()
+{
+    const char *device = "/dev/video0";
+    int fd = open(device, O_WRONLY);
+
+    if (fd < 0) {
+        QMessageBox::critical(this, "V4L2 Test",
+                              QString("Failed to open V4L2 device %1.\n"
+                                      "Error: %2\n\n"
+                                      "To fix this, run:\n"
+                                      "sudo modprobe v4l2loopback video_nr=0")
+                                  .arg(device)
+                                  .arg(strerror(errno)));
+        return;
+    }
+
+    // Test if device supports V4L2_PIX_FMT_RGB24
+    struct v4l2_format fmt;
+    memset(&fmt, 0, sizeof(fmt));
+    fmt.type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+    fmt.fmt.pix.width = 1280;
+    fmt.fmt.pix.height = 720;
+    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
+    fmt.fmt.pix.field = V4L2_FIELD_NONE;
+    fmt.fmt.pix.bytesperline = 1280 * 3;
+    fmt.fmt.pix.sizeimage = 1280 * 720 * 3;
+
+    if (ioctl(fd, VIDIOC_S_FMT, &fmt) < 0) {
+        ::close(fd);
+        QMessageBox::warning(
+            this, "V4L2 Test",
+            QString("V4L2 device %1 exists but doesn't support RGB24 format.\n"
+                    "Error: %2")
+                .arg(device)
+                .arg(strerror(errno)));
+        return;
+    }
+
+    ::close(fd);
+    QMessageBox::information(
+        this, "V4L2 Test",
+        QString("✓ V4L2 device %1 is working correctly!\n\n"
+                "You can now:\n"
+                "• View output with: ffplay %1\n"
+                "• Use in OBS as Video Capture Device\n"
+                "• Record with: ffmpeg -f v4l2 -i %1 output.mp4")
+            .arg(device));
+}