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Onscreen Preview Video Size (Osprey2000 OPI)

Message by John Reilly on Tuesday, February 11, 2003 at 18:51
Location: United States Joined: Friday, February 07, 2003 Posts: 3 Profile Search www Quote

Ah, it's as we suspected then. We'll have to find a workaround.

Thanks for the response, smeek!

-John Reilly

Message by smeek on Tuesday, February 11, 2003 at 14:56
Location: United States Joined: Tuesday, February 05, 2002 Posts: 60 Profile Search www Quote

The beginning stages of the OPI pipeline specify what size to capture video. Later stages of the OPI pipeline such as MPEG compression and video window display must use the video captured from the preceeding stages. So if you capture the uncompressed video at 640x480 then you must specify the same size in the MPEG compression stage. It is possible to tell OPI to make a video display window of a different size but since it will still recieve video data from the capture stage the window would only show a part of the full image instead of scaling it to the specified size. You can see this behavior if you run the MpegEncode example program that comes with the OPI SDK with the following command line:

encode -t 2 -r 3000000 -o -s 5 -w 2

This encodes an MPEG2 file at FULL 640x480 resolution and displays a 320x240 window as it encodes. The video in the window is the upper left portion of the full resolution and not scaled to fit the window. So after this long winded explantion the answer is no, OPI will not support this. This same functionality is working correctly using the DirectShow EncodeDemo. (Source also provided as part of the SDK).

Message by John Reilly on Friday, February 07, 2003 at 16:00
Location: United States Joined: Friday, February 07, 2003 Posts: 3 Profile Search www Quote

We are working on an app to encode MPEG2 video using the Osprey2000 card.

The app itself is written in C# using Microsoft VisualStudio.NET, and we wrote a little COM object wrapper class (in VisualC++) to allow .NET to access the functions available in the Osprey OPI.

Things are working very well with the exception of one problem. We'd like to encode the mpeg2 video to disk at the full frame size, and at the same time preview the video to the screen at half size (320x240). The problem is, we can't get it to do both. If we encode to disk at full size, the preview is full size as well. If we code the preview to be 320x240, the encoded video on disk is 320x240 also.

Will the OPI allow us to have both sizes at once? If so, what are the correct parameters that need to be set in order to get this to work? What should their values be?

Like I said, we can get full size *or* 320x240 to work, but not both. Any help would be greatly appreciated.

Thank you!

-John Reilly

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