MLT Multimedia Framework

Recent News

v7.40.0 released

Jun 24, 2026

You can download it from GitHub.

The highlights of this version are expanded compatibility and capabilities for OpenFX plugins and a new audio noise reduction filter and link.

Framework

• Some fixes for win32_fopen().
• Security fixes for time formatting in mlt_properties.
• Security fix to disable deprecated ante & post properties in mlc_consumer.
• Added more properties to metaschema.yaml (new version 7.2):
  • audio_formats
  • video_formats
  • layout-hint
  • hide-label
  • normalized_default

Modules

• Added audio_formats and image_formats properties to all service metadata.
• Many improvements to the openfx module:
  • fixed potential overflows in snprintf() calls
  • multi-threading: frame- and slice-based
  • many compatibility fixes
  • added support for 2D and 3D numeric parameters (uses mlt_rect)
  • fixed preview scaling
  • fixed the default for choice (values in metaschema.yaml) parameters
  • fixed some effects rendering upside-down.
• Added rnnoise module for background audio noise reduction (depends on librnnoise).
• Added HDR10 SMPTE ST 2084 (PQ) properties to the decklink consumer:
  • hdr_red_x
  • hdr_red_y
  • hdr_green_x
  • hdr_green_y
  • hdr_blue_x
  • hdr_blue_y
  • hdr_white_x
  • hdr_white_y
  • hdr_max_luminance
  • hdr_min_luminance
  • hdr_max_cll
  • hdr_max_fall
• Added the .lot file name extension for the loader producer to use glaxnimate.
• Visual quality improvements for animations in the qtblend filter and transition.
• Updated spatialaudio module to the libspatialaudio 0.4.0 API.
• Fixed a signed int overflow in pgm producer.
• MSVC compatibility fixes for kdenlivetitle producer and frei0r, plusgpl, jackrack, openfx, rtaudio, & resample modules.
• Fixed choppy playback and deadlocks in the decklink consumer.
• Fixed libopus audio encoder warning about frame_duration in avformat consumer.
• Fixed crash in avformat consumer with unsupported attached_pic format.
• Fixed plugin bundles for vst2 filters on macOS.
• Fixed the frame position in the consumer producer.
• Hardened string formatting for metadata properties in the vorbis producer.
• Fixed typewriter in qtext filter lags when rate properties changed.

Other

• Skip Qt preflight for XML-only consumers in melt.

v7.38.0 released

Apr 22, 2026

You can download it from GitHub.

The highlights of this version are basic, minimal support for OpenFX plugins and hardware scaling for preview scaling with hwaccel decoding.

Framework

• Added dynamic hash table for mlt_properties for better performance.
• Fixed memory corruption in mlt_pool.
• Added warning on file open failure when parsing in mlt_properties.

Modules

• Added basic support for OpenFX filter plugins. OpenFX has many features. This is a summary of what is NOT yet included:
  • GPU rendering
  • exotic parameter types: Integer2D, Integer3D, Double3D, Custom, Bytes, Page, PushButton
  • plugin-driven keyframe animation; but MLT-driven does work
  • tile-, slice-, or frame-based multi-threading (only plugin internal threading)
  • multi-resolution
  • temporal clip access
  • overlays & dialogs
  • timeline queries (e.g. getTime())
  • generator, transition, retimer
  • parametric curves
• Added hwaccel_scale filter with preview scaling (scale_vaapi, scale_vulkan, scale_d3d11, scale_vt (macOS)).
• Added an environment variable MLT_AVFORMAT_HWACCEL_PPS to provide a limiter to hwaccel because transfering uncompressed video between memory CPU and GPU memory is heavy. PPS = maximum pixels per second. Anything over it skips hwaccel.
• Added lut parameter to avformat producer.
• Added attached_pic property to avformat consumer.
• Added movit.overlay_blend video filter.
• Added compositing property to movit.overlay transition.
• Added constant-power crossfade to mix audio transition.
• Added rounded corner support for rect in kdenlivetitle.
• Added typewriter properties to subtitle filter.
• Added underline and strikethrough to the text and qtext filters.
• Changed qtext style property to support family named styles.
• Added anchor point support for arbitrary rotations in qtblend.
• Allow relative paths for images in kdenlivetitle.
• Updated Glaxnimate module to version 0.6.0.
• Switched to QImage scaling when downscaling in qtblend.
• Deprecated obscure and watermark filters.
• Install the jackrack module’s blacklist files.
• Fixed subtitle stream type metadata.
• Fixed mutex initialization in avformat no-validate mode.
• Fixed crash when using linearblend deinterlacer.
• Fixed black bar with HEVC hwaccel decode and scale on Windows.
• Fixed crash with hardware scaler and interlaced video.
• Fixed converting 8-bit full to limited range with hwaccel.
• Fixed alpha in 12-bit ProRes with alpha.
• Fixed movit linear color not matching CPU filters.
• Fixed multi consumer making extra linear color conversions.
• Fixed regression writing raw FLAC.
• Fixed qtblend filter returning unexpectedly large frames.
• Fixed qtext outline encroaching on fill color.
• Fixed wrong last+ frame when eof=loop in Glaxnimate.
• Fixed brightness filter on track below a clip with transparency.

Other

• Fixed crash during exit cleanup in melt.
• Continued build improvements for MSVC.
• A lot of metadata fixes and improvements.
• Many fixes to API documentation.
• Added C++ and Python to the API docs.
• Added two 10-bit VP9 encoding presets.

v7.36.0 released

Dec 29, 2025

You can download it from GitHub.

This version adds image processing in linear color on the CPU (previously only Movit). Plus, it extends 10-bit video processing on the CPU to many more services.

Framework

• Added mlt_image_default_colorspace()
• Added mlt_image_default_trc()
• Added mlt_image_default_primaries()
• Added mlt_color_convert_trc()
• Added the mlt_consumer property mlt_color_trc to drive a new color_transform normalizer filter. This sets the color transfer function to use for image/video effects. It is beneficial and correct to use linear color for any pixel mixing whether for blending or interpolation.
• Removed atexit(mlt_factory_close) in mlt_factory_init(). Close the factory yourself if you feel the need to (not generally needed when exiting a process).
• Prevent possible crash in mlt_service_connect_producer().
• Added mlt_profile_is_valid() and Mlt::Profile::is_valid().
• Fixed crash on invalid profile (CVE-2025-65834) in:
  • mlt_consumer_start()
  • mlt_factory_producer()
  • xml producer

Modules

• Drop support for Qt 5.
• Fixed bad color in luma transition’s dissolve (regression in v7.34.0).
• Fixed HLG HDR broken in decklink consumer (regression in v7.34.0).
• Fixed warnings when flushing audio in the avformat consumer.
• Added support for hwaccel=vulkan to the avformat producer.
• Added a color_transform normalizer filter to the core module to convert all image/video producers to and from linear color. It is abstract in the core module and drives the following filters:
  • avfilter.zscale
  • sws_colortransform
  • avfilter.scale
• Added filter sws_colortransform that is more efficient than avfilter.swscale but requires FFmpeg 8.
• Changed the default property values of the null consumer:
  • real_time: -1
  • terminate_on_pause: 1
• Changed the luma and movit.luma transitions to progress linearly with linear color_trc.
• Fixed the alpha channel dropped by the xml-clip producer.
• Added mlt_image_rgba64 format to:
  • avcolor_space filter
  • avdeinterlace filter
  • affine filter and transition
  • audiolevelgraph filter
  • audiospectrum filter
  • audiowaveform filter
  • autofade filter
  • avformat producer and consumers
  • box_blur filter
  • brightness filter
  • pillar_echo filter
  • color producer
  • dropshadow filter
  • dynamictext filter (when used with qtext)
  • frei0r.alpha0ps filter
  • frei0r.alphagrad filter
  • frei0r.alphaspot filter
  • frei0r.bluescreen0r filter
  • frei0r.select0r filter
  • frei0r.transparency filter
  • gpsgraphic filter
  • gpstext filter
  • gradientmap filter
  • hslprimaries filter
  • hslrange filter
  • kdenlivetitle producer
  • lift_gamma_gain filter
  • lightshow filter
  • mask_apply (when used with qtblend)
  • movit.convert filter
  • outline filter
  • qtblend filter and transition
  • qtcrop filter
  • qtext producer
  • shape filter
  • spot_remover filter
  • strobe filter
  • subtitle filter (when used with qtext)
  • swscale filter
  • text filter (when used with qtext)
  • timeremap link
  • timer filter (when used with qtext)
  • vqm transition
• Changed the mask_apply filter default transition to qtblend.
• Removed the maximum for the alpha property on the brightness filter so that you can increase the opacity of an existing alpha channel.
• Fixed background image scaling in the gpsgraphic filter.
• Fix audio artifacts with pcm_s24le in mkv in avformat producer.

Other

• Removed bitrate and quality limits in the vp9 and webm avformat presets.
• Fixed melt on Windows not reading file path/name with extended characters (regression in v7.34.0).
• Fixed building the ruby bindings with Ruby 3.0.
• More fixes for MSVC.
• Removed win32/strptime.c and replaced with Qt functions.
• Stop showing melt usage on error exit.

v7.34.0 released

Nov 3, 2025

You can download it from GitHub.

This versions adds 10-bit video processing on the CPU, but you must ensure you are using compatible filters and transitions.

Framework

• Added mlt_image_rgba64 format. This change touched core, avformat, and qt modules as well.
• Added mlt_color_trc, mlt_color_primaries, and more mlt_colorspaces along with functions:
  • mlt_image_color_trc_name
  • mlt_image_color_trc_id
  • mlt_image_colorspace_name
  • mlt_image_colorspace_id
  • mlt_image_color_pri_name
  • mlt_image_color_pri_id
• Fixed some minor memory leaks with cppcheck.

Modules

• Added rgba and rgba64 formats to the luma transition.
• Added rgba64 format to affine filter and transition.
• Added rgba64 format to the qtblend transition.
• Added support for FFmpeg 8 to the avformat module.
• Fixed audio panner filter for 5.1 channel layout.
• Fixed converting 10-bit full to limited range in avformat producer (regression in v7.30.0).
• Fixed shadow not working for multi-line template titles in kdenlivetitle producer.
• Fixed mask_apply filter with custom transition.
• Added input_chmask & output_chmask properties to mono filter.
• Added channel_mask property to LADSPA/LV2/VST2 filters.
• Added channel_mask to the volume filter.
• Added an outline video filter.
• Fixed a deadlock on image with a % in the name in qimage producer.
• Added scrubbing to the decklink consumer.
• Fixed & not decoded to & in the xml producer.
• Fixed converting BT.709 to BT.2020 in the avformat module.
• Fixed building a ladspa module without JACK as dependency.
• Deprecate a JACK Rack XML file in the jackrack and ladspa modules.
• Added filter qtblend_mode.
• Fixed incorrect alpha channel breaking optimization of qtblend.
• Fixed pixel format gbrap (Ut Video with alpha channel) in the avformat producer.
• Fixed opencv_tracker filter on cut playlist clips.
• Fixed warning about missing color range for avfilters that use it (e.g. avfilter.colorspace).
• Added typewriter properties to the qtext filter.
• Fixed color distortion or a crash if using hwaccel with orientation rotation in avformat producer.

Other

• Enable Qt 6 and disable Qt 5 modules in CMake by default.
• Disable the SDL1 module in CMake by default.
• Changed melt now exits with 1 if the producer is invalid.
• Various changes to work with MSVC compiler.
• Changed SVT-AV1 encode presets to VBR for Opus audio.
• Fixed initializing Qt on the main thread in melt.
• Documented the -progress2 option for melt.
• Increased the minimum C++ version to C++20.
• Converted many modules to use CMake find_package().
• Added libgen.c and libgen.h for MSVC.

v7.32.0 released

May 7, 2025

You can download it from GitHub.

Framework

• Added mlt_service_set_consumer() and `Mlt::Service::set_consumer().
• Optimized mlt_multitrack to not request a frame from a producer that is both hidden and muted.

Modules

• Fixed pixel format for VP8/VP9 streams in avformat producer.
• Fixed yuva422p pixel format in avformat producer.
• Added MLT_AVFORMAT_HWACCEL & MLT_AVFORMAT_HWACCEL_DEVICE environment variables to avformat producer.
• Updated decklink module for recent hardware and drivers.
• Added colorspace and color_trc (including HDR) properties to the decklink consumer.
• Fixed silencing extra audio channel (e.g. 6 => 8) in decklink consumer.
• Fixed 5.1 C/LFE channels swapped over HDMI in decklink consumer.
• Fixed text outline had sharp angles in kdenlivetitle producer.
• Fixed default gamma to be Rec. 709 for 10-bit Y’CbCr from movit module.
• Added support for HLG gamma to movit module (requires ddennedy/movit fork).
• Fixed opencv_tracker filter should require multiple keyframes to be ready.
• Fixed OpenCV crash on rect <= 1 pixel in opencv_tracker filter.
• Fixed aspect ratio in qtblend filter and transition.
• Fixed QT_QPA_PLATFORM=offscreen not working in qt and glaxnimate modules.
• Improved preview scaling in qtblend filter.
• Fixed requesting huge images on multiple qtblend filters or transitions.
• Fixed sdl2 consumer on macOS.
• Fixed the strobe filter not working with movit.
• Fixed color and gamma using timeremap link with movit.
• Fixed consumer properties (e.g. channels) missing on qglsl consumer injected by the xml producer.

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