Changing format of media stream during playback for media source

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Changing format of media stream during playback for media source

Hello to all.


I have problem with changing of format of my source during playback, i.e. without
reconnect it's stream and creating new presentation descriptor.


I need to change width and height of image, so I need to make a new media type with new parametres and I need to tell about new type to my media stream. There is the event MEStreamFormatChanged in Media Foundation, that is raised by media stream. I call it when commit changes inside my source:


hr = QueueEventWithIUnknown(m_pStream, MEStreamFormatChanged, S_OK, pMediaType);

where m_pStream - pointer to my stream, pMediaType - pointer to new media type.

It's returnes S_OK; but after application deliver a control to the player, that
render source, it hang on and the image doesn't displayed.
Tell me please, maybe, there are some errors in usage with this event, or there are
another methods to change stream format during playback, without stopping



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Changing format of media stream during playback for media source

  • Yeshia

    Queueing an MEStreamFormatChanged event on the IMFMediaStream in question is indeed the right way to do this. The fact that it's not working might be due to a couple things:

    • Did you make sure that the MEStreamFormatChanged event gets queued exactly between the last MEMediaSample event for the old width/height and the first MEMediaSample for the new width/height
    • It's possible that there's a component downstream that is not equipped to handle your new pMediaType. Double-check all the attributes on your new pMediaType to make sure they're right.
      • Are you using any custom MFTs (transforms) in the topology Did you make sure they can handle a media type change like this

    If you're also writing the application, then you should pay attention to the status codes on the events you get back from the Media Session. Are any of them failures Are you getting any MEError events

    Hope this helps...



  • Dual Cortex

    • Yes, I'm sure that MEStreamFormatChanged event gets queued exactly between the last MEMediaSample event for the old width/height and the first MEMediaSample for the new width/height
    • I use MFT Grayscale. It supports all widths\heights I offer him. But I couldn't change width\height during playback.

    I have next questions: who have to perfome source's events My application Or they are perfomed automatically by media session, for example Need I to restart session in case of changing media type of my source And how do new parametres, width and height, come into force I mean, how does stream descriptor get know about them

    Thanks.
  • Changing format of media stream during playback for media source
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