in our company we want to live encode a HD1080-videostream from a "Decklink HD Extreme 2" to MPEG-4 while parallel showing a small preview window. This should be done on an Intel Q9650 (QuadCore 3,0GHz/core), 2 GB RAM and Windows XP SP3.
Unfortunately, the resulting videos in all of our tests aren't really good; the preview and the video both have visible frameloss (about 18-20 fps instead of 25 fps). While encoding, the cpu usage is about 65-70%, so this can't be the reason.
Our DirectShow-filtergraph contains two "Avi decompressors", which we suspect of being the main reason for the frameloss; the codec is very good and very fast (see graph below). The "Avi decompressor"s are inserted behind the capture source and convert the HDYC colorspace coming from the card to a color format the encoder and the video renderer understand (UYVY or something else).
Is there any way to bypass the "Avi decompressor"s? What about the "Blackmagic Design Decoder (DMO)"-filter, it understands HDYC too, but if we insert it in our graph, we only get a black screen and the encoded video's size remains at 64 KB... what are we doing wrong? (The video renderer is not connectable to the "Blackmagic Design Decoder (DMO)" either).