Decomb parameter overview

Below you can find a detailed overview over all the parameters of Decomb.

Telecide parameters

Telecide(reverse, swap, firstlast, guide, gtresh, post, treshold, dthreshold, blend, chroma, y0, y1, debug). Using the default parameters you'd get Telecide(reverse=false, swap=false, firstlast=false, guide=0, gtresh=15, post=true, treshold=15, dthreshold=9,blend=true, chroma=false, y0=0, y1=0, debug=false). Or, if you're lazy as I am you just write Telecide(). In fact you only have to specify parameters that are different from the default parameters.

reverse (true/false) can be used to swap the order of the field matching. The default is reverse=false

swap (true/false) can be used to swap the field order. Very few DVD sources but also some captured sources can have the field order switched and you'll get interlaced output even though the source is progressive. You can actually test for that in DVD2AVI by selecting Video -> Field Operation -> Swap Field order and then preview the movie. The default is swap=false, if you want to swap field write swap=true.

firstlast (true/false) can be used to blend the first and last frame of a video if they have a missing field which would cause the field matching to fail. The default is firstlast=false.

guide (0-2) can be used to improve field matching when the source type is known. guide can be a number between 0 and 2 where the default guide=0 doesn't tell decomb anything about the source, guide=1 is to be used when the source is NTSC 3:2 pulldown material and guide=2 for PAL material. If in doubt about the source type leave it at zero.

gtresh (0-100) gives a threshold for the discrepancy between predicted and calculated field matches to reset a found IVTC pattern. The default is gtresh=15.

post (true/false) indicates whether telecide will perform postprocessing (deinterlace or blend according to a setting we'll see later on) on the frames that could not be reconstructed. The default is post=true but you can use post=false if you have a really clean source.

threshold (0-255) sets a threshold for the interlacing detection in postprocessing. The lower the value the less it takes for a frame to be considered to be interlaced. The default is threshold=15.

dthreshold (0-255) sets a threshold for the detection sensitivity of interlaced areas when a frame has been detected as being combed (you can change that detection sensitivity using the treshold parameter). This setting corresponds to the treshold parameter of most deinterlacing algorithms. The default setting is dthreshold=9.

blend (true/false) will indicate whether interlaced frames will be blended (smoother image and better motion but slight ghosting) or interpolated (sharper, but a little jumpier). The default is blend=true and normally gives better results.

chroma (true/false) includes chrominance in the deinterlacing calculations along with the luminance values that are considered by default. Especially Anime sources may look better using this option. The default is chroma=false which means that chroma values are not considered.

y0 and y1 (0-4095, 0-4095) define an exclusion band for the field matching. Lines between y0 (starting line) and y1 (ending line) will not be used in the field matching calculations. This can be useful to exclude overlayed data like subtitles from the calculations. The default is y0=0,y1=0.

debug (true/false) enables or disables debug output (use dbgview from sysinternals to capture that output). The default is debug=false which turns of debug output.

FieldDeinterlace parameters

FieldDeinterlace(full, threshold, dthreshold, blend, chroma, debug). The default parameters correspond to FieldDeinterlace(full=false, threshold=15, dthreshold=9, blend=true, chroma=false, debug=false) or simply FieldDeinterlace().

full (true/false) selects whether to process all frames or only frames that have been detected as being combed. The default is full=false which will only treat frames detected as being combed.

threshold (0-255), dthreshold (0-255), blend (true/false), chroma (true/false) and debug (true/false) correspond to the respective functions in telecide.

Decimate parameters

Decimate(cycle, mode, threshold, debug). The default settings correspond to Decimate(cycle=5, mode=0, threshold=0, debug=false) or simply Telecide().

cycle (0-25) indicates to remove 1 frame in n frames where n is the number you enter as parameter. The default is cycle=5 and removes one frame in 5 which is what we need to restore a telecined 29.97fps source to 23.976fps.

mode (0-1) determines what to do with frames determined to be most similar to their preceding frame in each cycle. The default mode=0 discards that frame, mode=1 the frame would be blended with the previous frame. This can be useful if you have a hybrid 30/24fps source and don't want the 30fps parts to be jerky by discarding some of the frames. Usually, movies/series that contain both live action and CG stuff are hybrid (for instance Andromeda and Babylon5).

threshold (0-99) can help prevent blended frames on 30fps content when using mode=1. If the difference between frames is larger than this threshold a frame will be be passed through untouched whereas if the threshold is lower than the value you've set the frame will be blended. The default threshold=0 will let all frames pass through untouched. This parameter has no influence when you use mode=0, and if you use mode=1 a value between 25 and 50 is reasonable.

debug (true/false) corresponds to the debug function in telecide.