在C＃中使用DirectShow AsyncReader

Question

I am running an AsyncReader to open a shared MPG file that is being downloaded by another application (progressive download). The shared MPG file is created with FILE-SHARE-READ | FILE-SHARE-DELETE | FILE-SHARE-WRITE FILE-SHARE-READ | FILE-SHARE-DELETE | FILE-SHARE-WRITE FILE-SHARE-READ | FILE-SHARE-DELETE | FILE-SHARE-WRITE shared permissions. I have even tried every combination of those flags.

Here's the problem: within C# the AsyncReader.Load method returns a error:

file in use

Within C++ it does not. C++ opens the file just fine.

Any idea why this is?

Answer 1

Any idea why this is?

This is because File Source (Async) Filter is opening file exclusively, without allowing others to progressively write to the file in the same time.

Code for same/similar asynchronous reader from old SDK, where it was available as a sample, contains:

// Open the requested file
HANDLE hFile = CreateFile(lpszFileName,
                          GENERIC_READ,
                          FILE_SHARE_READ,
                          NULL,
                          OPEN_EXISTING,
                          0,
                          NULL);

Note FILE_SHARE_READ . Your options are:

1. Complete progressive download before opening for playback
2. Build a custom reader from SDK sample and change the file opening mode to allow writing as you play it