Render Profile Parameters Explained

Property Presets

Kdenlive now makes use of property presets delivered by the melt project (see MLT Presets). These presets are referenced by the properties= <preset> syntax. In the example illustrated, the render profile is referencing lossless/H.264. This refers to a property preset found in file H.264 found on the system at

Windows:

C:\Program Files\kdenlive\share\mlt\presets\consumer\avformat\lossless

Linux:

/usr/share/mlt/presets/consumer/avformat/lossless

On a default install, all the < presets> referenced in the render settings in Kdenlive will be referring to presets found in

Windows:

C:\Program Files\kdenlive\share\mlt\presets\consumer\avformat\

Linux:

/usr/share/mlt/presets/consumer/avformat/

You reference presets found in subdirectories of this folder using a <subdirname>/<profile> syntax as shown in the example above. [code] properties=lossless/H.264 g=120 crf=%quality ab=%audiobitrate+'k'

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The preset files found at /usr/share/mlt/presets/consumer/avformat/ and C:\Program Files\kdenlive\share\mlt\presets\consumer\avformat\, respectively, are simple text files that contain the melt parameters that define the rendering. An example is shown below. These are the same parameters that were used in earlier versions of Kdenlive.

Contents of lossless/H.264: [code] f=mp4 acodec=aac ab=384k vcodec=libx264 intra=1 vb=0 g=0 bf=0 preset=medium qscale=1 qp=0 coder=ac

meta.preset.extension=mp4 meta.preset.note=Intra-frame only, lossless compressed MPEG-4 AVC with AAC audio

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How to Read Them

Essentially, the parameters are instructions for ffmpeg which is used for encoding the video and audio streams. Hence it should not come as a surprise that the parameters are well documented by the ffmpeg project.

In the example above the parameters are: [code] f=mp4 acodec=aac ab=384k vcodec=libx264 intra=1 vb=0 g=0 bf=0 preset=medium qscale=1 qp=0 coder=ac

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Another example for DVD output: [code] f=dvd vcodec=mpeg2video acodec=mp2 b=5000k maxrate=8000k minrate=0 bufsize=1835008 mux_packet_s=2048 mux_rate=10080000 ab=192k ar=48000 s=720x576 g=15 me_range=63 trellis=1 profile=dv_pal_wide pass=2

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Looking up the ffmpeg options translates these parameters as follows:

Main option is: [code] -f fmt force format

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Video options are: [code] -vcodec codec force video codec ('copy' to copy stream) -pass n select the pass number (1 or 2) -b bitrate set bitrate (in bits/s) -vb bitrate set video bitrate (in bits/s) -s size set frame size (WxH or abbreviation) -me_range limit motion vectors range (1023 for DivX player) -trellis rate-distortion optimal quantization

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Audio options are: [code] -acodec codec force audio codec ('copy' to copy stream) -ab bitrate set audio bitrate (in bits/s) -ar rate set audio sampling rate (in Hz)

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The AVCodecContext AVOptions include: [code] -b set bitrate (in bits/s) -maxrate set max video bitrate tolerance (in bits/s) -minrate set min video bitrate tolerance (in bits/s) -g set the group of picture size

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All the render profile options are documented in the ffmpeg documentation.

See also MLT Presets for more details on the MLT preset property. *[RGB]: Red Green Blue *[VFX]: Visual Effects *[feathering]: Smoothing or blurring the edges of a feature *[LFO]: Low-Frequency Oscillation *[dB]: decibel *[LUFS]: Loudness Units Full Scale *[AI]: Artificial Intelligence *[LLM]: Large Language Model *[HSV]: Hue, Saturation, Value *[SOP/Sat]: S(lope), O(ffset), P(ower) / SATuration *[CDL]: Color Decision List *[HSL]: Hue, Saturation, Lightness - Using HSL color space is useful for subtle color changes *[px]: pixel *[hh:mm:ss:ff]: hours:minutes:seconds:frames *[Hz]: Hertz *[CIE]: Commission internationale de l'éclairage, French for International Commission on Illumination *[DCI]: Digital Cinema Initiative *[nadir]: direction pointing directly below a particular location *[OS]: Operating System *[decibel]: Unit of measurement (dB) for sound levels *[clipping]: A form of distortion that limits a signal once it exceeds a threshold *[Spectrogram]: Visual representation of the spectrum of frequencies of a signal as it varies with time *[prevent clipping]: Dynamic range compression (DRC)is an audio signal processing operation that reduces the volume of loud sounds or amplifies quiet sounds, thus reducing or compressing an audio signal's dynamic range. *[SNR]: Signal-to-Noise Ratio *[dbFS]: Decibels relative to full scale *[QHD]: Quad-HD *[UHD]: Ultra High Definition *[XML]: Extensible Markup Language *[fps]: frames per second *[NTSC]: National Television Standard Committee - defined the TV system used in the United States, Japan and many other countries *[PAL]: Phase Alternating Line - a colour encoding system for analogue television *[LFE]: Low Frequency Effects *[RAW]: The RAW file format is digital photography's equivalent of a negative in film photography: it contains untouched, raw pixel information straight from the digital camera's sensor *[DSLR]: Digital Single Lens Reflex *[DOF]: Depth of Field *[NDF]: Neutral Density Filter *[AVI]: Audio Video Interleave *[BT.601]: A standard from 1982 defining how RGB color primaries get turned into the YCbCr channels used by modern codecs *[BT.709]: A standard from 1990 which does the same at BT.601 but the transfer coefficients are slightly different *[grep]: A Unix command-line utility for searching plain-text data sets for lines that match a regular expression *[MLT]: Media Lovin' Toolkit - An open source software multimedia framework designed and developed for tv broadcasting