我已经实现了两个IMFByteStream
接口,其中一个称为MediaByteStream,用于非存储内存流,另一个称为StoreByteStream(是的,我知道),用于内存存储。
将以下代码放置在您的IMFByteStream
实现中将消除您的可寻址错误,并且不会影响您的流式传输能力。
/// <summary>
/// Retrieves the characteristics of the byte stream.
/// </summary>
/// <param name="pdwCapabilities">Receives a bitwise OR of zero or more flags. The following flags are defined. [out]</param>
/// <returns>The result of the operation.</returns>
HRESULT MediaByteStream::GetCapabilities(
DWORD *pdwCapabilities)
{
HRESULT hr = S_OK;
// Stream can read, can write, can seek.
*pdwCapabilities = MFBYTESTREAM_IS_READABLE | MFBYTESTREAM_IS_WRITABLE | MFBYTESTREAM_IS_SEEKABLE;
// Return the result.
return hr;
}
你可以,如果你想实现IMFByteStream
接口的Seek
方法,但在你的情况下(网络流),你可以只返回搜索位置。
/// <summary>
/// Moves the current position in the stream by a specified offset.
/// </summary>
/// <param name="SeekOrigin">Specifies the origin of the seek as a member of the MFBYTESTREAM_SEEK_ORIGIN enumeration. The offset is calculated relative to this position. [in]</param>
/// <param name="qwSeekOffset">Specifies the new position, as a byte offset from the seek origin. [in]</param>
/// <param name="dwSeekFlags">Specifies zero or more flags. The following flags are defined. [in]</param>
/// <param name="pqwCurrentPosition">Receives the new position after the seek. [out]</param>
/// <returns>The result of the operation.</returns>
HRESULT MediaByteStream::Seek(
MFBYTESTREAM_SEEK_ORIGIN SeekOrigin,
LONGLONG qwSeekOffset,
DWORD dwSeekFlags,
QWORD *pqwCurrentPosition)
{
HRESULT hr = S_OK;
_seekRequest = true;
// Select the seek origin.
switch (SeekOrigin)
{
case MFBYTESTREAM_SEEK_ORIGIN::msoCurrent:
// If the buffer is less or same.
if ((qwSeekOffset + _position) < size)
_position += qwSeekOffset;
else
_position = size;
break;
case MFBYTESTREAM_SEEK_ORIGIN::msoBegin:
default:
// If the buffer is less or same.
if (qwSeekOffset < size)
_position = qwSeekOffset;
else
_position = size;
break;
}
// Get the current position in the stream.
*pqwCurrentPosition = _position;
// Return the result.
return hr;
}
您需要一个媒体源,对于不可查找的流很好。一些消息来源需要寻找的是整个观点,并且他们检查这些上限以确保寻求可用。 –
我的目标媒体源的内容类型是ASF。可以创建不需要可查找字节流的ASF媒体源? – pawel
我认为所有的寻求都是“前进”的,所以最有可能实现一个简单的寻找流(只是读取不需要的数据) –