The debug window of Comskip.

When ComSkip is started with the –w or --debugwindow switch a graphics window will appear. Once finished Comskip will NOT automatically exit but has to be closed manually by killing the console window or by hitting ESCAPE. Do not use the debug window when Comskip is called automatically from GBPVR or other PVR software.

This window will show the decoded mpeg in black and white.
Next to this it will show some information to debug the settings of Comskip.

Another use of the debugwindow is when Comskip is used to review the output of  a previous run of Comskip. This is done by starting Comskip with the name of the previously generated .txt file as its single parameter. The detailed analysis information is not available in this mode but it provides some additional keys for modifying the commercial locations and writing out the resulting information.


Frame number

At the top the frame four numbers are shown. The first number is the frame number of the current frame. The second number is the brightness. A letter ‘B’ after the brightness indicates the current frame is Black. The third number is the volume. A letter ‘S’ after the volume indicates the current frame is regarded as Silent. The fourth number is the uniformity of the frame. A letter ‘U’ after the uniformity indicates the frame is regarded as uniform.


Aspect Ratio information
Two blue lines are drawn at the border between the black bars at the bottom and the top and the active video.
This will allow to check if the detection settings for  max_brightness, test_brightness and max_avg_brightness are correct because these are use to detect the black parts of the screen
The blue lines will always stay minimally the border size from the top and bottom of the video size.

Logo information
A rectangle will be draw around the logo position as soon as it  is found.  As soon as the detection level is above the logo_threshold the logo detection mask will overlay the logo to indicate the tested pixels. If no logo is detected the frame is red.


Frame bar information
At the top a frame bar is shown indicating information detected for each frame.
The bottom 5 pixels of the bar signal the detection of silence. Any sound volume level below max_volume will be show as green upon white background. Speech without music should give a lot of silence.
The next 5 pixels on the bar signal the detection of black frames. A red line on a white background signals a black frame or any other frame that is signaling an equally relevant scene change.

When silence is detected on a black frame both above bars will be drawn in black. These lines are the principle cut points for Comskip
The next 5 pixels of the bar signal the presence of logo. The presence of logo is signaled by black, the absence by white. When logo is disabled its presence is signaled by gray bars in stead of black.
The next 10 pixels of the bar signal the aspect ratio. A blue line on a white background depicts the detected aspect ratio where the height of the line above the logo bar is proportional to the detected aspect ratio. When the detection is finished or when live_tv=1 this bar is also used to show the position of commercials. A gray bar signals commercial and a white bar signals show.

When cut_on_ar_change=1 in the ini file (default) changes in the aspect ratio will create additional cut points when sufficient logo is found.
The next 5 pixels are used to show the position of the commercials as indicated in an optional reference file as soon as detection is finished. Black depicts where commercial are expected, white depicts where show is expected.


Graph on video information

The colored graphs enabled/disabled by pressing the ‘g’ key show detailed information about the recording.
From the bottom to the top it shows brightness, sound, non_uniformity, scene change, logo match, aspect ratio and black bar positions.
Through zooming (‘z’) and unzooming (‘u’) of the timeline you can have both a good overview and see on a per frame basis the transitions. The parts of the graphs that reach a value below the Blackframe limits (max_avg_brightness, max_volume, non_uniformity) get a white color.

The bottom four graphs have an additional white/red line showing the block average value that is red when above the “total average times punish_threshold” and that is white otherwise.



When decoding of the mpeg is finished or when the .csv file is loaded it is possible to navigate through the mpeg file. Navigation can be done with the cursor keys and with page up/down. Look at the frame number to see the step taken for each of the keys. A red vertical line in the frame bar shows the current position. Left clicking with the mouse in the frame bar repositions the current frame to the click position. This can be used to quickly review the correctness of the commercial detection.

Pressing ‘n’ skips to just before the next black frame, pressing ‘p’ skips to just after the previous next black frame. Pressing ‘e’ skips to just before the end of the next block, pressing ‘b’ skips to just after the beginning of the previous block

Video and frame position is not always 100% aligned, the actual error depends on the mpeg file being used.


Commercial reviewing mode

When started with the .txt file as its single parameter the frame number is shown and in the debug bar l black bars show the location of the detected commercials.

The navigation is identical except the letter keys.

The ‘n’ key jumps to the next end of a detected commercial.

The ‘p’ key jumps to the previous beginning of a commercial.

The ‘b’ key sets the beginning of the commercial that ends after the current frame position

The ‘e’ key sets the end of the commercial that begins before the current frame position.

The ‘i’ key inserts a short commercial at the current location

The ‘d’ key deletes the commercial around the current frame position

The ‘w’ key writes the current commercial list to the .txt file.


To stop the session, close the console window or hit the ESCAPE key