Reading a QCTools Document

The QCTools Document is designed to be a self-descriptive metadata document that stores analytical metadata about video and audio frames and may be quickly rendered in QCTools version 0.5 or later. The QCTools Document is an XML expression of FFprobe's XML expression as defined by the ffprobe schema at http://www.ffmpeg.org/schema/ffprobe.xsd. For more information about FFprobe's XML expression please visit: http://www.ffmpeg.org/schema/ffprobe.xsd; for additional information about FFprobe's XML expression: http://ffmpeg.org/ffprobe.html#xml.

In addition to frame metadata, the QCTools Document stores metadata values output from four evaluative filters: signalstats, cropdetect, psnr, and ebur128.

• signal stats
  The signalstats filter is a project of the QCTools project. Signalstats outputs information about the range of values used in luminance and chrominance video planes as well as details of hue and saturation and pixel labeling tests such as vertical line repetition, temporal outliers, and broadcast range adherence. More info: http://ffmpeg.org/ffmpeg-filters.html#signalstats.

• crop detect
  The cropdetect filter detects how a given frame may be cropped to remove black (or nearly black) borders from the edges of the video. It can detect if video has been letterboxed or pillarboxed or other bordering rows or columns of black pixels. More info: http://ffmpeg.org/ffmpeg-filters.html#cropdetect.

• psnr
  Within the QCTools Document the psnr filter is used specifically to visually compare field 1 and field 2. The filter accepts field 1 and field 2 as two separate inputs and provides quantification of the visual difference between those two images for each plane (Y, U, and V) as well as for the overall image. This data is presented in both Peak Signal to Noise Ratio (PSNR) and Mean Square Error (MSE). More info: ffmpeg.org/ffmpeg-filters.html#psnr.

• ebur128
  The ebur128 filter is a volume detection filter that measures perceived loudness according to the EBU standard. More info: http://ffmpeg.org/ffmpeg-filters.html#ebur128.

1. Library Versions
2. Frames and Tags