Try to understand your request, do you want to use decode only, input an interlaced stream and output a output stream with the same frame rate but each frame has a double line number? (duplicate each line as the next line to it in output)
You might use the argument "-di <bob or adi>" for sample_decode to do this. Refer to the following document about how to use sample_decode:
Some DVD are encoded as 23.976 progressive and special flags inserted so decoders do telecine to generate 29.97 interlaced frames. Does the mfx encoder support this? Can the mfx decoder ignore the flags and return the original 23.976 progressive frames?
So you want this special video of progressive with interlaced flag set in the stream? In this case, your app should prefer not to do deinterlacing.
Normally the configuration sequence in the decode app is:
1. Set the initial parameters
2. Read the stream header and overwrite the parameters in #1 with the new parameters from stream.
I think you might to check you code to make sure, the progressive parameter is set between #2 and #3.
You can download our tutorial 0.0.4 at the following page:
You can get the initial parameters example from simple_decode project. In general, any parameter is fine because they will be overwrite by the input from the stream header.