I’m trying to come up with an AVStream minidriver for audio / video
capture. I’m using AVSHWS as my reference and trying to add audio capture
functionality.
Towards this, I have added an additional pin and pin info to filter
descriptor -
const
KSPIN_DESCRIPTOR_EX
CaptureFilterPinDescriptors [CAPTURE_FILTER_PIN_COUNT] = {
//
// Video Capture Pin
//
{
&CapturePinDispatch,
NULL,
{
0, // Interfaces (NULL, 0 ==
default)
NULL,
0, // Mediums (NULL, 0 == default)
NULL,
SIZEOF_ARRAY(CapturePinDataRanges),// Range Count
CapturePinDataRanges, // Ranges
KSPIN_DATAFLOW_OUT, // Dataflow
KSPIN_COMMUNICATION_BOTH, // Communication
&PIN_CATEGORY_CAPTURE, // Category
&g_PINNAME_VIDEO_CAPTURE, // Name
0 // Reserved
},
#ifdef _X86_
KSPIN_FLAG_GENERATE_MAPPINGS | // Pin Flags
#endif
KSPIN_FLAG_PROCESS_IN_RUN_STATE_ONLY,
1, // Instances Possible
1, // Instances Necessary
&CapturePinAllocatorFraming, // Allocator Framing
reinterpret_cast <PFNKSINTERSECTHANDLEREX>
(CCapturePin::IntersectHandler)
},
//
// Audio Capture Pin
//
{
&AudioCapturePinDispatch,
NULL,
{
0, // Interfaces (NULL, 0 == default)
NULL,
0, // Mediums (NULL, 0 == default)
NULL,
SIZEOF_ARRAY(AudioCapturePinDataRanges),// Range Count
AudioCapturePinDataRanges, // Ranges
KSPIN_DATAFLOW_OUT, // Dataflow
KSPIN_COMMUNICATION_BOTH, // Communication
&KSCATEGORY_AUDIO, // Category
&g_PINNAME_AUDIO_CAPTURE, // Name
0 // Reserved
},
KSPIN_FLAG_DO_NOT_INITIATE_PROCESSING | // Flags
KSPIN_FLAG_PROCESS_IN_RUN_STATE_ONLY |
KSPIN_FLAG_FIXED_FORMAT,
1, // Instances Possible
0, // Instances Necessary
&AudCapturePinAllocatorFraming, // Allocator Framing
reinterpret_cast <PFNKSINTERSECTHANDLEREX>
(CAudioCapturePin::AudioIntersectHandler)
}
};
As a first step, I'm trying to see if this audio pin can be connected to
any standard render pin. But I get the following error in graphEdit -
Return code 0x80040274 (No Video port hardware is available or hardware is
not responding). However, the video capture pin is working fine
I checked what is happening through debugView. Looks like a whole lot of
IntersectHandler callbacks are being made. There are no errors caught
either.
Here's a snippet of my intersectHandler implementation -
...
const GUID AudioInfoSpecifier =
{ STATICGUIDOF(KSDATAFORMAT_SPECIFIER_WAVEFORMATEX) };
NT_ASSERT(Filter);
NT_ASSERT(Irp);
NT_ASSERT(PinInstance);
NT_ASSERT(CallerDataRange);
NT_ASSERT(DescriptorDataRange);
NT_ASSERT(DataSize);
ULONG DataFormatSize;
//
// Specifier FORMAT_VideoInfo for VIDEOINFOHEADER
//
if (IsEqualGUID(CallerDataRange->Specifier, AudioInfoSpecifier) &&
CallerDataRange->FormatSize >= sizeof(KSDATARANGE_AUDIO)) {
PKSDATARANGE_AUDIO callerDataRange =
reinterpret_cast <PKSDATARANGE_AUDIO> (CallerDataRange);
PKSDATARANGE_AUDIO descriptorDataRange =
reinterpret_cast <PKSDATARANGE_AUDIO> (DescriptorDataRange);
//
// If the passed buffer size is 0, it indicates that this is a size
// only query. Return the size of the intersecting data format and
// pass back STATUS_BUFFER_OVERFLOW.
//
if (BufferSize == 0) {
*DataSize = sizeof(KSDATAFORMAT_WAVEFORMATEX);
return STATUS_BUFFER_OVERFLOW;
}
//
// Check that the other fields match
//
if ((callerDataRange->MaximumBitsPerSample !=
descriptorDataRange->MaximumBitsPerSample) ||
(callerDataRange->MaximumChannels !=
descriptorDataRange->MaximumChannels) ||
(callerDataRange->MaximumSampleFrequency !=
descriptorDataRange->MaximumSampleFrequency) ||
(callerDataRange->MinimumBitsPerSample !=
descriptorDataRange->MinimumBitsPerSample) ||
(callerDataRange->MinimumSampleFrequency !=
descriptorDataRange->MinimumSampleFrequency))
{
return STATUS_NO_MATCH;
}
PKSDATAFORMAT_WAVEFORMATEX WaveFormat =
reinterpret_cast <PKSDATAFORMAT_WAVEFORMATEX> (Data);
DataFormatSize =
sizeof(KSDATAFORMAT_WAVEFORMATEX);
RtlCopyMemory(
&WaveFormat->DataFormat,
&descriptorDataRange->DataRange,
sizeof(KSDATAFORMAT)
);
//
// Verify that the provided structure is large enough to
// accept the result.
//
if (BufferSize < DataFormatSize)
{
return STATUS_BUFFER_TOO_SMALL;
}
WaveFormat->WaveFormatEx.wFormatTag = WAVE_FORMAT_PCM;
WaveFormat->WaveFormatEx.nChannels =
(WORD)descriptorDataRange->MaximumChannels;
WaveFormat->WaveFormatEx.nSamplesPerSec =
descriptorDataRange->MaximumSampleFrequency;
WaveFormat->WaveFormatEx.wBitsPerSample =
(WORD)descriptorDataRange->MaximumBitsPerSample;
WaveFormat->WaveFormatEx.nBlockAlign =
(WaveFormat->WaveFormatEx.wBitsPerSample / 8) *
WaveFormat->WaveFormatEx.nChannels;
WaveFormat->WaveFormatEx.nAvgBytesPerSec =
WaveFormat->WaveFormatEx.nSamplesPerSec *
WaveFormat->WaveFormatEx.nBlockAlign;
WaveFormat->WaveFormatEx.cbSize = 0;
WaveFormat->DataFormat.SampleSize =
WaveFormat->WaveFormatEx.nBlockAlign;
//
// Copy over the KSDATAFORMAT, followed by the actual VideoInfoHeader
//
*DataSize = DataFormatSize;
//
// REVIEW - Perform other validation such as cropping and scaling checks
//
return STATUS_SUCCESS;
} // End of AudioInfoSpecifier
...
Please help me out here !!
--
Manu.
