signalstats

Evaluate various visual metrics that assist in determining issues associated with the digitization of analog video media.

By default the filter will log these metadata values:

YMIN

Display the minimal Y value contained within the input frame. Expressed in range of [0-255].

YLOW

Display the Y value at the 10% percentile within the input frame. Expressed in range of [0-255].

YAVG

Display the average Y value within the input frame. Expressed in range of [0-255].

YHIGH

Display the Y value at the 90% percentile within the input frame. Expressed in range of [0-255].

YMAX

Display the maximum Y value contained within the input frame. Expressed in range of [0-255].

UMIN

Display the minimal U value contained within the input frame. Expressed in range of [0-255].

ULOW

Display the U value at the 10% percentile within the input frame. Expressed in range of [0-255].

UAVG

Display the average U value within the input frame. Expressed in range of [0-255].

UHIGH

Display the U value at the 90% percentile within the input frame. Expressed in range of [0-255].

UMAX

Display the maximum U value contained within the input frame. Expressed in range of [0-255].

VMIN

Display the minimal V value contained within the input frame. Expressed in range of [0-255].

VLOW

Display the V value at the 10% percentile within the input frame. Expressed in range of [0-255].

VAVG

Display the average V value within the input frame. Expressed in range of [0-255].

VHIGH

Display the V value at the 90% percentile within the input frame. Expressed in range of [0-255].

VMAX

Display the maximum V value contained within the input frame. Expressed in range of [0-255].

SATMIN

Display the minimal saturation value contained within the input frame. Expressed in range of [0-~181.02].

SATLOW

Display the saturation value at the 10% percentile within the input frame. Expressed in range of [0-~181.02].

SATAVG

Display the average saturation value within the input frame. Expressed in range of [0-~181.02].

SATHIGH

Display the saturation value at the 90% percentile within the input frame. Expressed in range of [0-~181.02].

SATMAX

Display the maximum saturation value contained within the input frame. Expressed in range of [0-~181.02].

HUEMED

Display the median value for hue within the input frame. Expressed in range of [0-360].

HUEAVG

Display the average value for hue within the input frame. Expressed in range of [0-360].

YDIF

Display the average of sample value difference between all values of the Y plane in the current frame and corresponding values of the previous input frame. Expressed in range of [0-255].

UDIF

Display the average of sample value difference between all values of the U plane in the current frame and corresponding values of the previous input frame. Expressed in range of [0-255].

VDIF

Display the average of sample value difference between all values of the V plane in the current frame and corresponding values of the previous input frame. Expressed in range of [0-255].

YBITDEPTH

Display bit depth of Y plane in current frame. Expressed in range of [0-16].

UBITDEPTH

Display bit depth of U plane in current frame. Expressed in range of [0-16].

VBITDEPTH

Display bit depth of V plane in current frame. Expressed in range of [0-16].

The filter accepts the following options:

stat

out

stat specify an additional form of image analysis. out output video with the specified type of pixel highlighted.

Both options accept the following values:

‘tout’

Identify temporal outliers pixels. A temporal outlier is a pixel unlike the neighboring pixels of the same field. Examples of temporal outliers include the results of video dropouts, head clogs, or tape tracking issues.

‘vrep’

Identify vertical line repetition. Vertical line repetition includes similar rows of pixels within a frame. In born-digital video vertical line repetition is common, but this pattern is uncommon in video digitized from an analog source. When it occurs in video that results from the digitization of an analog source it can indicate concealment from a dropout compensator.

‘brng’

Identify pixels that fall outside of legal broadcast range.

color, c

Set the highlight color for the out option. The default color is yellow.

Examples

• Output data of various video metrics:

  ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames
  

• Output specific data about the minimum and maximum values of the Y plane per frame:

  ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN
  

• Playback video while highlighting pixels that are outside of broadcast range in red.

  ffplay example.mov -vf signalstats="out=brng:color=red"
  

• Playback video with signalstats metadata drawn over the frame.

  ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt
  

  The contents of signalstat_drawtext.txt used in the command are:

  time %{pts:hms}
  Y (%{metadata:lavfi.signalstats.YMIN}-%{metadata:lavfi.signalstats.YMAX})
  U (%{metadata:lavfi.signalstats.UMIN}-%{metadata:lavfi.signalstats.UMAX})
  V (%{metadata:lavfi.signalstats.VMIN}-%{metadata:lavfi.signalstats.VMAX})
  saturation maximum: %{metadata:lavfi.signalstats.SATMAX}