IAMAsyncReaderTimestampScaling interface

Enables a pull-mode source filter to support larger file sizes.

When to implement

Filters that implement the IAsyncReader interface can implement IAMAsyncReaderTimestampScaling on their output pins. The File Source (Async) and File Source (URL) filters implement this interface.

When to use

Parser filters that connect to pull-mode source filters can use this interface to support very large media files. Query the source filter's output pin for the interface.

Applications should not use this interface.


The IAMAsyncReaderTimestampScaling interface inherits from the IUnknown interface. IAMAsyncReaderTimestampScaling also has these types of members:


The IAMAsyncReaderTimestampScaling interface has these methods.


Gets the filter's time-stamping mode.


Sets the filter's time-stamping mode.



In the pull model, the parser filter requests data from the source filter by calling IAsyncReader::Request. The input to this method is a media sample. The time stamp on the sample specifies the location to read in the stream, as a byte offset.

By default, the time stamp uses the following formula: Time = byte offset × 10000000. This scaling factor limits the effective file size to about 860 GB. To support larger file sizes, call SetTimestampMode with the value TRUE. This call sets the scaling factor to 1, so the formula becomes: Time = byte offset.


Minimum supported client

Windows 7 [desktop apps only]

Minimum supported server

Windows Server 2008 R2 [desktop apps only]


Strmif.h (include Dshow.h)

See also

Pull Model