I'm using MPEG Streamclip in order to convert .mkv (720p) to .mp4. I never convert the whole movie, just part of it. I prefer it unscaled, keeping the original frame rate. Consequently, I never check "frame blending" or "better downscaling". I check only "B-Frames". As far as it concerns the sound, MPEG-4 AAC, Stereo, 48kHz, 256 kbps. The only problem are the options "interlaced scaling" and "deinterlace video". For now I check only "deinterlace video". What's the difference between them and which one of two should I prefer? Which settings do you suggest for the best possible results? Thank you!