IAMTimecodeReader::GetTimecode method (strmif.h)
[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]
The GetTimecode method retrieves the most recent timecode, userbit, and flag values available in the stream.
Syntax
HRESULT GetTimecode(
[out] PTIMECODE_SAMPLE pTimecodeSample
);
Parameters
[out] pTimecodeSample
Pointer to a TIMECODE_SAMPLE structure.
Return value
Returns an HRESULT value that depends on the implementation of the interface.
Remarks
Use this method to monitor the timecode and to parse duplicates and discontinuities.
The timecode contains undefined bits, called userbits. Applications can use these bits to store synchronization information or other custom information.
DV and MPEG Camcorder Implementation
The MSDV driver supports reading SMPTE timecode or absolute track numbers (ATN). The MSTape driver supports reading the relative time counter (RTC). To read time information on these devices, do the following:Set the dwFlags member of the TIMECODE_SAMPLE structure to one of the following values.
| Constant | Description |
|---|---|
| ED_DEVCAP_TIMECODE_READ | Timecode (DV) |
| ED_DEVCAP_ATN_READ | Absolute track number (DV) |
| ED_DEVCAP_RTC_READ | Relative time counter (MPEG tape) |
The timecode member of the TIMECODE_SAMPLE structure is a TIMECODE structure. Initialize that structure's dwFrames member to zero.
All other structure members are ignored.
When the method returns, the dwFrames member contains the time information, in the following format.
| Time Information | Format |
|---|---|
| Timecode | Hours, minutes, seconds, and frames, as a binary coded decimal (BCD) value: 0xhhmmssff. |
| ATN | Track number. |
| RTC | Hours, minutes, seconds, and frames, as a BCD value: 0xhhmmssff. The most significant bit of the frames byte is a sign bit. If the frame count is not available, the remaining frame bits are set to 0x7F. |
Also, the dwUser member receives the blank flag bit from the device, which has one of the following values.
| Value | Description |
|---|---|
| 0x00 | Not a discontinuity. |
| 0x01 | Discontinuity. |
Requirements
| Requirement | Value |
|---|---|
| Minimum supported client | Windows 2000 Professional [desktop apps only] |
| Minimum supported server | Windows 2000 Server [desktop apps only] |
| Target Platform | Windows |
| Header | strmif.h (include Dshow.h) |
| Library | Strmiids.lib |