How to Play a Sequence of Files

[MFPlay is available for use in the operating systems specified in the Requirements section. It may be altered or unavailable in subsequent versions. ]

This topic describes how to play a sequence of audio/video files using MFPlay.

The topic Getting Started with MFPlay shows how to play a single media file. You can also use MFPlay to play a sequence of files.

Synchronous (Blocking) Method

  1. Call the IMFPMediaPlayer::CreateMediaItemFromURL method. The method creates a media item.
  2. Call IMFPMediaPlayer::SetMediaItem to queue the media item for playback.
  3. Call IMFPMediaPlayer::Play to start playback.

These steps are shown in the following code.


HRESULT OpenMediaFile(IMFPMediaPlayer *pPlayer, PCWSTR pwszURL)
{
    HRESULT hr = S_OK;
    
    IMFPMediaItem *pItem = NULL;

    hr = pPlayer->CreateMediaItemFromURL(
        sURL, 
        TRUE,  // Blocking call
        0,     // User data.
        &pItem
        );

    if (SUCCEEDED(hr))
    {
        hr = pPlayer->SetMediaItem(pItem);
    }

    if (SUCCEEDED(hr))
    {
       hr = pPlayer->Play();
    }

    if (pItem)
    {
        pItem->Release();
    }
    return hr;
}


The CreateMediaItemFromURL method takes the following parameters:

  • The first parameter is the URL of the file.
  • The second parameter specifies whether the method blocks. Specifying the value TRUE, as shown here, causes the method to block until the media item is created.
  • The third parameter associates an arbitrary DWORD_PTR value with the media item. You can get this value later by calling IMFPMediaItem::GetUserData.
  • The fourth parameter receives a pointer to the IMFPMediaItem interface of the media item.

Asynchronous (Non-Blocking) Method

Avoid the blocking option if you call CreateMediaItemFromURL from your UI thread, because it can take a noticeable amount of time to complete. The method typically opens a file or network connection and reads enough data to parse the file headers, all of which can take time. Therefore, it is generally better to set the second parameter to FALSE. This option causes the method to perform asynchronously. When the asynchronous option is used, the last parameter must be NULL:


    hr = pPlayer->CreateMediaItemFromURL(
        sURL, 
        FALSE,  // Non-blocking call.
        0,      // User data.
        NULL    // Must be NULL for the non-blocking call.
        );


When the media item is created, your application receives an MFP_EVENT_TYPE_MEDIAITEM_CREATED event. The data structure for this event contains a pointer to the media item. Pass this pointer to the SetMediaItem method to queue the item for playback.


void OnMediaItemCreated(MFP_MEDIAITEM_CREATED_EVENT *pEvent)
{
    HRESULT hr = S_OK;
    if (FAILED(pEvent->header.hrEvent))
    {
        // Handle error. (Not shown.)
    }
    else
    {
        hr = g_pPlayer->SetMediaItem(pEvent->pMediaItem);
    }
}


Requirements

MFPlay requires Windows 7.

Related topics

Using MFPlay for Audio/Video Playback

 

 

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