User Guide Capture and Record

April 5, 2026 at 5:50 PM Edit on GitHub

Capture and Record

WinDV’s main interface is a single resizable dialog with a tab control that switches between Capture and Record modes.

Dialog Layout

CDVToolsDlg is the application’s only top-level window, derived from CDialog. There is no document/view pattern and no frame window. The dialog is resizable; the initial size sets the minimum size constraint.

The dialog contains one instance of CDV (the m_video member) mapped to the IDC_VIDEO picture control. CDV inherits CStatic, so it is a legitimate child window that can host the preview renderer as a grandchild window.

Key Controls

Control ID Type Purpose
IDC_VIDEO CDV (CStatic) Preview window host
IDC_TOOL_TAB CToolTab Owner-draw tab control
IDC_VSRC Static text Current capture source device name
IDC_VSRC_SEL Button Opens device selection dialog
IDC_FDST CDropFilesEdit Capture destination filename base
IDC_FDST_SEL Button Opens file browse dialog
IDC_FSRC CDropFilesEdit Record source file list
IDC_FSRC_SEL Button Opens multi-file browse dialog
IDC_VDST Static text Current record destination device name
IDC_VDST_SEL Button Opens device selection dialog
IDC_CAPTURE Button Toggle capture start/pause
IDC_RECORD Button Toggle record start/pause
IDCANCEL Button Cancel / reset to idle
IDC_CONFIG Button Opens configuration property sheet
IDC_DVCTRL Checkbox Enable/disable tape transport control
IDC_STATUS Static text Primary status message
IDC_STATUS2 Static text DV recording timestamp display
IDC_STATUS3 Static text Queue fill level display
IDC_COUNTER Static text Elapsed capture/record time
IDC_PICTURE Button Logo (clicking opens About dialog)

CDropFilesEdit is a CEdit subclass that accepts file-drop events. For IDC_FSRC (multi-file record source) a " | " separator is used between filenames. For IDC_FDST (single-file capture destination) a transform callback CaptureFilenameExtractBase() strips the extension so the field always shows only the base name.

Tab Control and Mode Switching

IDC_TOOL_TAB is a CToolTab (owner-draw) with two items:

Tab index Label Mode
0 “Video Capture” Capture (FireWire to AVI)
1 “Video Recording” Record (AVI to FireWire)

Tab-change Mechanics

TCN_SELCHANGE on the tab control routes to OnSelchangeToolTab(), which:

  1. Reads m_toolTab.GetCurSel().
  2. For each control in ctrlProperties[], calls ShowWindow(SW_SHOW or SW_HIDE) based on whether (1 << sel) & tabMask is non-zero.
  3. Calls InitVideo() to rebuild the pipeline for the newly active tab.

InitVideo() for tab 0 calls CDV::BuildCapturing() (live preview begins immediately). InitVideo() for tab 1 calls CDV::Destroy() and displays a prompt.

Pressing the Cancel button or Escape also calls InitVideo(), which resets the pipeline to the idle/paused state for the active tab rather than closing the dialog. The default CDialog::OnCancel() behaviour (close dialog) is suppressed.

Tab Item Sizing

SetToolTabItemSize() recalculates the width of each tab item so that all items together fill the tab control width with a half-item gutter on each side:

itemWidth = tabControlWidth * 2 / (itemCount * 2 + 1)

This is called from both OnInitDialog() and OnSize() so the tabs resize with the dialog.

Proportional Resize System

All controls in the dialog resize proportionally as the user drags the window borders. The system uses a static array of CtrlProperties structures defined at the top of DVToolsDlg.cpp:

static struct CtrlProperties {
    int id;             // control resource ID
    int dx, dw;         // horizontal left-edge and right-edge percentage anchors
    int dy, dh;         // vertical top-edge and bottom-edge percentage anchors
    int tabMask;        // which tabs show this control
} ctrlProperties[] = { ... };

How the Percentages Work

When OnSize(cx, cy) fires:

deltaX = cx - m_originalRect.right    (change from initial width)
deltaY = cy - m_originalRect.bottom   (change from initial height)

For each control, the new position is computed as:

new_left   = originalLeft   + (dx  * deltaX) / 100
new_top    = originalTop    + (dy  * deltaY) / 100
new_width  = originalWidth  + ((dw - dx) * deltaX) / 100
new_height = originalHeight + ((dh - dy) * deltaY) / 100

dx and dy anchor the control’s leading edges; dw and dh anchor the trailing edges.

  • dx = 0: left edge is fixed (left-anchored).
  • dx = 100: left edge tracks the right side (right-anchored, fixed width).
  • dw = 100, dx = 0: control stretches full width.
  • dy = 100, dh = 100: control is anchored to the bottom.

Two named percentage constants are defined to describe the layout zones:

#define XL 25   // left zone boundary (25% from left)
#define XR 75   // right zone boundary (75% from left, or 25% from right)

Layout Table (Selected Controls)

Control dx dw Behaviour
IDC_VIDEO 0 100 Fills entire client area width
IDC_TOOL_TAB XL=25 XR=75 Centred band; narrows as dialog widens
Device/file labels XL XL Fixed-width, pinned to 25% mark
Device/file edits XL XR Stretch between 25% and 75% marks
Buttons (sel, cfg, action) XR XR Pinned to 75% mark, fixed width
IDC_STATUS XL XR Full-width status stretches with dialog
IDC_COUNTER, status2/3 XR XR Pinned to right

All controls use dy = 100, dh = 100 so their vertical positions track 100% of the height change, keeping them pinned to the bottom of the dialog.

Status Display and Timer Updates

A 200 ms WM_TIMER (timer ID 1) is started by SetTimer(1, 200, NULL) when the pipeline becomes active and stopped by KillTimer(1) in InitVideo().

OnTimer() performs two jobs:

Auto-exit check: If m_exitOnFinish is set (from the -exit command-line flag) and the pipeline has reached CDV::Finished, OnClose() is called immediately.

Status label updates (only when the text changes to avoid repaints):

Label Content
m_status (IDC_STATUS) Pipeline state; appends dropped-frame count
m_status2 (IDC_STATUS2) DV timestamp as DD.MM.'YY HH:MM:SS
m_counter (IDC_COUNTER) Elapsed time as H:MM:SS.t
m_status3 (IDC_STATUS3) Queue fill level; during capture also shows DV error count and percentage

During active capture (CDV::Capturing), m_status3 shows the queue load together with the current DV error statistics:

Q:N E:N/X.X%

where N (first) is the queue slot count, N (second) is the number of frames with at least one video error, and X.X% is the error rate. The error portion is omitted when no errors have been detected yet.

The elapsed time conversion:

REFERENCE_TIME t = m_video.GetTime();  // 100-ns units
t /= 1000000;       // -> tenths of a second
int ss = (int)(t % 10); t /= 10;
int s  = (int)(t % 60); t /= 60;
int m  = (int)(t % 60); t /= 60;
txt2.Format("%d:%02d:%02d.%01d", (int)t, m, s, ss);

SetThreadExecutionState(ES_DISPLAY_REQUIRED) is called in OnTimer() to prevent the monitor from blanking during active capture or recording sessions.

Custom Window Messages

WinDV defines several WM_USER-based messages for cross-thread notification. All are declared in DShow.h and routed via ON_MESSAGE entries in CDVToolsDlg’s message map.

Message Value Sender Handler
WM_DV_TIMECHANGE +201 Capturing OnDVTimeChange
WM_DV_LOWDISKSPACE +202 Capturing OnDVLowDiskSpace
WM_DV_SIGNALLOST +203 Capturing OnDVSignalLost
WM_DV_CHECK_COMPLETE +204 Capturing (post-capture) OnDVCheckComplete

OnDVTimeChange

Reads lParam as a time_t DV recording timestamp and updates the m_status2 label.

OnDVLowDiskSpace (v1.2.6)

Posted by CapturingThread when GetDiskFreeSpaceEx() reports fewer than 500 MB free on the capture destination drive. lParam carries the remaining free space in megabytes.

The handler:

  1. Formats the string "WARNING: Low disk space! X MB remaining" into m_status.
  2. Calls MessageBeep(MB_ICONEXCLAMATION) to produce an audible alert.

Capture continues; the handler does not stop or pause the pipeline. The warning is informational, allowing the user to decide whether to stop early.

OnDVSignalLost (v1.2.7)

Posted by CapturingThread when CDVQueue::GetWithTimeout() times out without receiving a frame or an EOS marker, indicating the FireWire signal was lost.

The handler:

  1. Sets m_status to "Signal lost - capture stopped.".
  2. Calls MessageBeep(MB_ICONEXCLAMATION).

The thread has already set the pipeline state to Finished before posting the message, so no additional stop call is required from the dialog.

OnDVCheckComplete (v1.6.0)

Posted by CapturingThread after the post-capture phase (AVI integrity check + SHA-256 + CSV log) completes. wParam is non-zero if the AVI check passed, zero if problems were found.

The handler reads CDV::GetLastCheckResult() and CDV::GetErrorStats() to build an extended status bar message:

AVI OK: N frames, PAL | DV: error-free
AVI OK: N frames, NTSC | DV errors: M frames (X.X%), worst: #F (N STA),
    audio: A frames [C CRITICAL]
AVI problem: <reason> | DV errors: ...

If the AVI check failed, MessageBeep(MB_ICONWARNING) is called. The full check result is available via CDV::GetLastCheckResult() for programmatic access (e.g., from the CLI check command).

Configuration Dialogs

The configuration button (IDC_CONFIG) opens a CPropertySheet with two pages:

CCaptureCfg

Exposes:

  • AVI type radio button (Type 1 / Type 2)
  • Discontinuity threshold (seconds)
  • Maximum frames per file
  • Frame decimation factor (EveryNth)
  • Date/time format string (with history combo)
  • Sequence digit count
  • Auto-stop on signal loss (IDC_CHK_AUTOSTOP, timeout in seconds)
  • SHA-256 checksum (IDC_CHK_SHA256) – when checked, a sha256sum-compatible sidecar file (.sha256) is written next to each captured AVI file after the post-capture phase completes. Controls CDV::m_enableSHA256.

CRecordCfg

Exposes:

  • AVI prefix list (pipe-delimited paths played before main file list)
  • AVI suffix list (pipe-delimited paths played after main file list)
  • Preview checkbox (enable/disable preview during recording)

The property sheet is created with PSH_NOAPPLYNOW because settings take effect only when a new pipeline is built. Live application would require a graph rebuild, which is not implemented. Changes made in the dialog are copied back to CDV and the CDVToolsDlg member variables only when the user confirms with OK.

Supporting Controls

CToolTab

CToolTab is a CTabCtrl subclass that overrides DrawItem() to draw tab items using the owner-draw style. It provides consistent styling across Windows versions without requiring visual styles.

CDropFilesEdit

CDropFilesEdit is a CEdit subclass that registers as a drop target and handles WM_DROPFILES. It accepts a separator string (for multi-file mode) and an optional transform callback.

For IDC_FSRC (Record source):

  • Separator: " | "
  • Transform: none
  • Multiple files dropped are joined with the separator.

For IDC_FDST (Capture destination):

  • Separator: "" (single file)
  • Transform: CaptureFilenameExtractBase strips the extension so only the base path is stored.

CVideoDeviceSel

A simple CDialog subclass that shows a list box populated with device friendly names returned by GetVideoSrcList() or GetVideoDstList(). Returns the selected index via GetSelection().