Re: Video Capture Performance with directshow

I'm not familiar with any of the specific filters OEM's add to the devices,
sorry I can't be more help.

As for your question about video encoding, that is similar what we're doing
today. The "Buffering" filter is inserted just before the WMV encoder and
buffers up unencoded video into RAM. The output pin on the filter is running
at below normal priority, so it slowly feeds data into the WMV encoder as
CPU is available. When the filter runs out of RAM it drops the oldest sample
that hasn't been delivered to the encoder.

If you have an algorithm you'd like to use, it would be fairly simple to
replace the Microsoft buffering filter with your own implementation. Your
filter would have to have one input and one output. The input pin would need
to accept MEDIATYPE_Video/Audio, and the output pin would need to output
MEDIATYPE_VideoBuffered/AudioBuffered. When you go to build your capture
graph you'd cocreate two instances of the filter, one for video and one for
audio. When you render the encoding portion of the graph your buffering
filter would be automatically inserted instead of the Microsoft buffering
filter.

Gary Daniels
Windows CE Multimedia and Graphics

This posting is provided "AS IS" with no warranties, and confers no rights.
You assume all risk for your use.

"SkyWaLKer" <shantanu.goel@xxxxxxxxx> wrote in message
news:1181242078.227759.317760@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Just found out that HTC devices ship with a filter named "HTC Source
Filter". Somewhere on directx.audio group I found out that someone had
delved into it a bit and found that it was a capture filter from HTC
(both audio and video). I checked in registry and that is true. So, it
must be some optimized filter that we can use for capture.
Now, I tried to enumerate the pins on this capture filter, for which I
have to first query for an IPersistPropertyBag interface on this
filter (used the clsid of the filter from the registry and
CoCreateInstance for it returns S_OK). But the QueryInterface returns
E_NOINTERFACE. Any opinions/suggestions here? Because the registry
clearyly shows that this is a capture filter. Is there any other way I
can use this filter?
---My Code---
HRESULT hResult = S_OK;
IGraphBuilder *pFilterGraph;
ICaptureGraphBuilder2 *pCaptureGraphBuilder;
htcDDR.Data1 = 0xA06DF275;
htcDDR.Data2 = 0xC4F3;
htcDDR.Data3 = 0x46C7;
htcDDR.Data4[0] = 0xB5;
htcDDR.Data4[1] = 0x20;
htcDDR.Data4[2] = 0x3A;
htcDDR.Data4[3] = 0x16;
htcDDR.Data4[4] = 0xB3;
htcDDR.Data4[5] = 0xD1;
htcDDR.Data4[6] = 0xB8;
htcDDR.Data4[7] = 0xC2;
hResult = CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC,
IID_IGraphBuilder,(void**)&pFilterGraph);
hResult = CoCreateInstance(CLSID_CaptureGraphBuilder, NULL,
CLSCTX_INPROC, IID_ICaptureGraphBuilder2,
(void**)& pCaptureGraphBuilder);

hResult = pCaptureGraphBuilder->SetFiltergraph( pFilterGraph );

IBaseFilter *pVideoCaptureFilter;
hResult=CoCreateInstance(htcDDR, NULL, CLSCTX_INPROC,
IID_IBaseFilter,
(void**)&pVideoCaptureFilter);

IPersistPropertyBag *pPropertyBag;

hResult=pVideoCaptureFilter->QueryInterface( IID_IPersistPropertyBag,
(void**) &pPropertyBag );
/* This is where I get the E_NOINTERFACE*/
---------------

Regards
Shantanu
On Jun 6, 10:11 pm, SkyWaLKer <shantanu.g...@xxxxxxxxx> wrote:
So I enumerated the filters present on my device (HTC Wizard/Qtek9100/
i-mate KJAM/T-Mobile MDA). Got 4 extra filters (i.e. not microsoft).
These filters were from HTC as the names suggested. 3 out of them were
for rendering video/audio and one mp3 decoder. The last one was named
"HTC DDR". Anyone knows what this does? Anyways, I tried to use the
CLSID of this filter in my IDMOWrapperFilter. A query interface on HTC
DDR for IDMOWrapperFilter return S_OK but when I tried to call the
Init method of IDMOWrapperFilter, it reurned E_NOINTERFACE. Any
suggestion??

On Jun 6, 3:31 pm, SkyWaLKer <shantanu.g...@xxxxxxxxx> wrote:

On Jun 6, 6:58 am, "Gary Daniels [MS]" <gary...@xxxxxxxxxxxxxxxxxxxx>
wrote:

Just as a follow up, depending on your device the manufacturer may
have put
in a third party video encoder, multiplexer, and file writer which
are
compatible with the DirectShow video capture pipeline. Most of these
are a
3GPP encoder for mms. You could try enumerating the filters available
in the
system (or look in the registry), to see if you can find one. If
there is
one available it will work exactly the same as the WMV encoder and
ASF
multiplexer, it'll just have different GUID's and potentially there
will be
an audio encoder also. As a starting point i'd recommend checking out
the
pictures and video's registry keys for the Windows Mobile camera
application
if the application that ships on the device supports a format other
than
WMV.

Hi Gary
Thnx for the reply. I'm at office right now and will try enumerating
the available filters when I go back. However I looked through the
registry for the filters (using keywords like video, encoder, DMO,
filter etc) and found out a few interesting things:
1. Found that only WMV9 is registered as a DMO video encoder.
2. Also found a complete list of filters (subkeys within a subkey
called "filters"). It listed all the known filters (GUIds as subkeys
and name given in description) like WMV9 encoder, audio encoder,
MPEG-1 decoder, Audio Capture, Video Capture etc, but there was no
other "encoder" listed. HOWEVER, the thing is that this list also
contained 3-4 other keys (GUIDs) which didn't have any description
given. Can these be the encoder GUIDs used by the OEM camera app? But
these dont have any corresponding DMO entries in the registry.
3. I also had smthing else in mind. If we can make the graph in such a
way that it buffers some samples and then encodes them, then buffers
the next samples and then encodes them, and write these directly to
the disk, then maybe we can alleviate this problem of encoding
delay..Any thoughts on that?
Regards
Shantanu

This posting is provided "AS IS" with no warranties, and confers no
rights.
You assume all risk for your use.

"GaryDaniels[MS]" <gary...@xxxxxxxxxxxxxxxxxxxx> wrote in
messagenews:466612e9$1@xxxxxxxxxxxxxxxxxxxxx

I suspect you're using the WMV encoder?

The memory usage spike you're seeing is the buffering filter
storing up as
much video as it can that's on it's way into the WMV encoder, once
it runs
out of ram it starts dropping samples. The app shouldn't stop
running
though, everything should continue to run (but probably very
slowly). Once
you stop the capture the samples will continue flow out of the
buffering
filter on the low priority thread which the video encoding happens
on.
Once encoding is completely finished (which may take many minutes
depending on the resolution, how much was buffered, and how fast
the CPU
is) you'll receive the stream control stopped event. Don't stop the
graph
until you receive that event, otherwise the buffered video will be
discarded.

To fix the problem you'll need to decrease the resolution of the
video
you're trying to capture. The root of the problem is the WMV
encoder just
can't encode the video fast enough for the resolution and quality
you've
selected, so it tries it's best and ends up with a few second long
slideshow. The WMV encoder provided in windows mobile is optimized
for
ARM, but WMV was primarily designed for the desktop and struggles
to
perform on low end devices. When it's running well, in my opinion
the
quality of the encoded video is better than MPEG at an equivalant
resolution, however it has a much higher CPU utilization at that
resolution which reduces its maximum resolution possible on mobile
devices
(well below what MPEG is capable of on the same CPU).

GaryDaniels
Windows CE Multimedia and Graphics

This posting is provided "AS IS" with no warranties, and confers no
rights.
You assume all risk for your use.

"SkyWaLKer" <shantanu.g...@xxxxxxxxx> wrote in message
news:1180796687.257341.166210@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi
I'm writing a directshow based solution for capturing window
(target
is WM 5.0). Its in native code.
Now, I've been able to get it all together after reading through
sample code on msdn and bits of info scattered here and there. But
my
problem is:
1. When I run it on my Pocket PC, the available RAM (Program
Memory)
diminshes rapidly irrespective of the time for which capturing is
done. It drops down to alarmingly low level (to around just 2 MB
free
ram remaining) and then the app conks out. BTW, the output file
size
is always a few KBs, so dont kjnow why so much ram is eaten.
2. No matter how long I wait between starting and stopping the
control
stream, the recorded video comes out to be juse a couple of
seconds at
max.

Basically what I'm doing in my code for starting stopping capture
is:
________________CODE________________
hResult=pFilterGraph->QueryInterface(&pMediaControl);
hResult =pMediaControl->Run();
OAFilterState state = State_Stopped;
while(state != State_Running)
pMediaControl->GetState(100, &state);

LONGLONG dwStart = 0, dwEnd = 0;
WORD wStartCookie = 1, wEndCookie = 2;
dwEnd=MAXLONGLONG;
//start capturing
hResult=pCaptureGraphBuilder->ControlStream(
&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video, pVideoCaptureFilter,
&dwStart, &dwEnd, 0, 0 );
Sleep(30000);
//Stop capturing
dwStart=0;
IMediaSeeking *pMediaSeeking;
hResult=pFilterGraph->QueryInterface(&pMediaSeeking );
hResult=pMediaSeeking->GetCurrentPosition( &dwEnd );
hResult= pCaptureGraphBuilder->ControlStream(
&PIN_CATEGORY_CAPTURE, &MEDIATYPE_Video, pVideoCaptureFilter,
&dwStart, &dwEnd, wStartCookie, wEndCookie );
long leventCode, param1, param2;

hResult =pFilterGraph->QueryInterface( IID_IMediaEventEx,
(void**)
&pMediaEvent );
hResult = pMediaControl->Stop();
_________________CODE______________________

So, please help me out as to :
1. How to avoid the memory loss while recording?
2. How to record for a longer length?

Regards
Shantz




.

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