how to use async IMFTransform?

mc 4,436

how to use IMFTransform for async? I want to encode nv12 to h264.

I have to use while and again and again .

Is there is way to do nothing .and do not need to start thread.

If I need to ProcessInput then it will call my asynccallback?

1 answer

Jeanine Zhang-MSFT 9,666 Reputation points Microsoft Vendor

2024-08-21T01:56:33.71+00:00

I suggest you could refer to the Doc: Asynchronous MFTs

You need to implement IMFMediaEventGenerator interface. An MFT sends out-of-band events through the IMFMediaEventGenerator interface. During streaming, the MFT requests data by sending an METransformNeedInput event. For each METransformNeedInput event, the client calls ProcessInput for the specified stream.

You needn't to call this function, but only respond to the events you receive.
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mc 4,436 Reputation points

2024-08-21T15:41:27.6533333+00:00

how to get IMFMediaEventGenerator please give me an demo. I tried asy your article. but failed.

Jeanine Zhang-MSFT 9,666 Reputation points Microsoft Vendor

2024-08-22T03:11:32.8+00:00

For more details about how to implement the IMFMediaEventGenerator interface, I suggest you could refer to the Doc: Implementing IMFMediaEventGenerator

mc 4,436 Reputation points

2024-08-22T15:50:44.2266667+00:00

then how to use it? which is implemented?

Jeanine Zhang-MSFT 9,666 Reputation points Microsoft Vendor

2024-08-23T05:30:30.2533333+00:00

The client calls IMFMediaEventGenerator::BeginGetEvent and IMFMediaEventGenerator::EndGetEvent to receive out-of-band events from the MFT.

When streaming starts, the client sends the MFT_MESSAGE_NOTIFY_START_OF_STREAM message.

During streaming, the MFT requests data by sending an METransformNeedInput event.

For each METransformNeedInput event, the client calls ProcessInput for the specified stream.

mc 4,436 Reputation points

2024-08-23T07:41:46.5266667+00:00

then how to use it? I have IMFTransform.

IMFTransform *transform=NULL;

how to use transform to use IMFMediaEventGenerator?

Jeanine Zhang-MSFT 9,666 Reputation points Microsoft Vendor

2024-08-28T08:46:58.46+00:00

Whether you want to know how to call IMFTransform::ProcessInput?

An object can use events to signal the completion of an asynchronous method. Whenever the object sends a new event, the event is placed in a queue. The application can request the next event from the queue by calling BeginGetEvent. Create the event queue by calling the MFCreateEventQueue function.

The events tell you when it is time to do ProcessInput and ProcessOutput, you are not supposed to call this randomly or in a poll fashion, only in response to events you receive.

Refer to the thread: https://stackoverflow.com/a/78893471

The MFT requests data by sending an METransformNeedInput event. For each METransformNeedInput event, the client calls ProcessInput for the specified stream. For each METransformHaveOutput event, the client calls ProcessOutput.

mc 4,436 Reputation points

2024-08-28T09:12:16.5733333+00:00

I still do not know how to use it. I have implemented it then how to use it? please give me an example.
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