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This SDK only works with devices released within the past 3 years. We regularly optimize and update the SDK to ensure compatibility and performance. We do not guarantee compatibility or provide technical support for devices older than 3 years.

# NET_SDK_PlayBackByTimeSync

### Interface Definition

C++C#

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    int NET_SDK_PlayBackByTimeSync(
        LONG lUserID,
        LONG* pChannels,
        LONG channelNum,
        DD_TIME* lpStartTime,
        DD_TIME* lpStopTime,
        HWND* hWnds,
        BOOL bFirstStream);

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    public static extern Int32 NET_SDK_PlayBackByTimeSync(
        Int32 lUserID,
        uint[] pChannels,
        Int32 channelNum,
        ref DD_TIME lpStartTime,
        ref DD_TIME lpStopTime,
        IntPtr[] hWnds,
        Boolean bFirstStream);

### Function Description

Different channels of the same device request synchronous playback, supporting switching between main stream and sub stream (synchronous playback is exclusive, and only synchronous playback or asynchronous playback can be selected during playback).

### Parameter Description

Parameters | Type | Remark
--- | --- | ---
lUserIDin | LONG | User ID, the return value of `NET_SDK_Login` or `NET_SDK_LoginEx`.
pChannelsin | LONG* | The channel number array to be played back. The channel number starts from 0.
channelNumin | LONG | The number of channels in the array pChannels.
lpStartTimein | `DD_TIME`* | The start time pointer of the file, refer to `DD_TIME`.
lpStopTimein | `DD_TIME`* | File end time pointer, refer to `DD_TIME`.
hWndsin | HWND* | The playback window handle (only supported on Windows platform). If it is set to null, the SDK can still receive the stream data but will not decode and display it.
bFirstStreamin | BOOL | Whether to play the main stream, false means the sub-stream.

### Return Value

- Type：unsigned int

- Remark：0 means failure, and a value greater than 0 means successful playback. For example, if 4 streams are played back simultaneously, the third one fails to play, and the others succeed, the return value is 11, which is 1011 in binary.

### Remarks

Synchronous playback does not support fast rewind function.

Error Code