What's Changed

Framework

• Added list-based image-conversion callback dispatch on mlt_frame.
  Use mlt_frame_append_convert_image() to register a converter instead of
  setting frame->convert_image directly. Multiple converters are tried in
  registration order; the first that succeeds wins. New public API:
  • mlt_frame_prepend_convert_image()
  • mlt_frame_append_convert_image()
  • mlt_frame_convert_image()
  • mlt_frame_next_convert_image()
  • mlt_frame_has_convert_image()
  • mlt_frame_copy_convert_image()
• API behavior change: mlt_frame_s::convert_image is now read-only after
  init and is permanently set to the dispatcher mlt_frame_convert_image().
  External code that set this field directly to a custom function will no
  longer have that function called. If you really need that (never heard of
  someone who does), clear the frame's "_convert_image_callbacks" property
  and use mlt_frame_append_convert_image() instead.
• fx_cut (Adjustment Clip) now applies its filters only to tracks
  below it. Higher tracks composite on top of the filtered result.
  New image-stack helpers used by tractor stacking and this path:
  • mlt_frame_prepend_image_from_service()
  • mlt_frame_push_image_with_fx_cut()
• Fixed crash applying a Movit (OpenGL) filter to an fx_cut (Adjustment Clip).
  Cross-producer image sharing (including the reverse fx_cut share) finalizes
  an in-progress Movit chain to rgba64 and does not copy producer-keyed
  _movit chain state. Same-producer prepends keep the GPU chain. Playlist
  fx_cut frames now set _producer so Movit can key the chain.
• Copy meta. and set. properties from the producer onto fx_cut frames
  so producer annotations reach tractor output. New public API:
  • mlt_producer_pass_frame_properties()
  • Mlt::Producer::pass_frame_properties()
• Changed the default audio sample format to float32 (mlt_audio_f32le).
  Added mlt_audio_format_id() and an mlt_audio_format property on the
  multi consumer. Integer/float conversion is lossless and symmetric
  (s16 and u8 round-trips are exact).
• Deprecated audio services that only support integer samples.
• Propagate per-track audio-level metadata to output frames (meta.audio.*).
• Improved mlt_property_is_anim() so strings that merely contain =
  (for example URLs) are not treated as animation.
• mlt_properties_get_data() no longer returns a data pointer for rect
  properties.
• Fixed signed integer overflow in mlt_luma_map_from_pgm.
• Fixed fx_cut in-point handling in mlt_transition.
• Fixed Android mlt++ builds by disabling ELF symbol versioning.
• Fixed a macOS crash in numeric property conversion caused by setlocale.
  Parsing and formatting no longer change the process LC_NUMERIC.

Modules

• Image converters (movit.convert, avcolor_space, imageconvert) are
  now attached data-driven via loader.ini key image_convert.
• Movit rgba64 is now a valid input as well as output: FlatInput is
  created with GL_UNSIGNED_SHORT and set_pixel_data() uses the 16-bit
  overload. Previously rgba64 was uploaded as 8-bit, which distorted the
  image when an OpenGL filter ran on an fx_cut.
• Added placebo GPU module (placebo.render, placebo.shader) using
  libplacebo for scaling, debanding, dithering, tonemapping, and mpv-style
  .hook shaders (D3D11 / Vulkan / OpenGL).
• Fixed deadlock in the decklink consumer when pausing, seeking, and
  resuming playback.
• Added ducking to the mix transition (duck_threshold, duck_attenuation,
  duck_level, duck_fade_in, duck_fade_out, and an optional prefix for
  duck_level on the frame).
• Added #frame+1# keyword in dynamictext (1-based frame number).
• Added more audio formats to the audiolevel filter.
• FFmpeg 9 support in avformat.
• Fixed 10-bit hevc_vaapi encoding.
• Log when the avformat consumer finishes.
• Fixed rnnoise only working with 48 kHz audio.
• frei0r.kaleid0sc0pe and frei0r.squigglevision report internal threading.
• Fixed frei0r.camerashake (and its blur) with preview scaling.
• Skip duplicate OpenFX plugins.
• USE_LV2 and USE_VST2 require USE_LADSPA; install LADSPA
  blacklist.txt without JACK; expand LV2_PATH correctly on Windows.
• Fixed affine and qtblend inside mask_apply.
• qtblend: flag to avoid double PAR normalization.
• Fixed luma transition alpha scaling, alpha when using a luma file, and
  documented the invert property.
• Fixed shape filter alpha subtraction for rgba.
• Fixed motion-tracker shapes clipping outside the frame.
• Fixed colorspace and range of cached images in qimage and pixbuf.
• Fixed crop with hardware decode+scale plus preview scale.
• Fixed subtitle filter rendering one frame past the end time, and
  subtitle_feed end-frame calculation.
• Fixed file-name buffer overflows in gpsgraphic and gpstext.
• Fixed the sdl2 consumer freezing on Windows after a few seconds.
• Fixed sdl2_audio hanging in consumer_stop() when stopped while paused.
• Added s32, float, s32le, f32le, and u8 to the noise producer,
  and s16, s32, s32le, f32le, and u8 to tone. Fixed tone
  integer conversion to match audioconvert.
• Fixed a double-free in the xml producer when a filter, transition,
  link, or producer fails to load.
• Fixed movit.convert leaking a Movit input on every frame when an
  effect chain is reused.
• Fixed the heart-rate keyword in gpstext (#gps_hr#).
• gpsgraphic no longer sets time_offset when a GPS file is first loaded.

Other

• melt prints progress at the end and exits non-zero when interrupted
  by a signal.
• Fixed melt on Windows ignoring window resize and keyboard transport.
• Fixed melt -jack option not working with PipeWire.

New Contributors

• @Magnussmari made their first contribution in #1270
• @doruphin made their first contribution in #1279
• @michaeljtbrooks made their first contribution in #1286
• @zhuowei made their first contribution in #1293
• @klg90 made their first contribution in #1307
• @darkdi made their first contribution in #1309
• @iDoMeteor made their first contribution in #1323

Full Changelog: v7.40.0...v7.42.0

What's Changed

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.

New Contributors

• @dirkmueller made their first contribution in #1226
• @Komzpa made their first contribution in #1231
• @guiodic made their first contribution in #1229
• @orbisai0security made their first contribution in #1250

Full Changelog: v7.38.0...v7.40.0

What's Changed

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.

New Contributors

• @oedmilsonfernandes made their first contribution in #1196
• @chocolateimage made their first contribution in #1211
• @balooii made their first contribution in #1110
• @guchangx made their first contribution in #1223

Full Changelog: v7.36.1...v7.38.0

This version fixes a regression creating a xml-clip producer or producer with a null profile. This broke, for example, nesting a MLT XML project file within another project in Shotcut.

Full Changelog: v7.36.0...v7.36.1

What's Changed

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

• Fixed melt on Windows not reading file path/name with extended characters (regression in v7.34.0).
• Removed bitrate and quality limits in the vp9 and webm avformat presets.
• 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.

New Contributors

• @gnampf1 made their first contribution in #1179

Full Changelog: v7.34.1...v7.36.0

Fixed compiling with Qt 5.

Full Changelog: v7.34.0...v7.34.1

What's Changed

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.

New Contributors

• @sammiler made their first contribution in #1141

Full Changelog: v7.32.0...v7.34.0

What's Changed

Framework

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

New Contributors

• @evertvorster made their first contribution in #1066

Full Changelog: v7.30.0...v7.32.0

What's Changed

Framework

• Fixed Mlt::Producer::set_creation_time() not exported on i686.
• Fixed Mlt::Properties::set(int64_t) symbol version.
• Fixed mlt_factory_init() on Linux/BSD may fail to initialize when compiled with -DRELOCATABLE.
• Added generic non-drop-frame timecode in mlt_property.c.
  Previously, it was only done for 30000/1001 and 60000/1001 frame rates, but 24000/1001 is especially important as well.
• Added support for MLT XML embedded in chains.
  This, along with xml-clip producer handles mismatching frame rate between parent and child producers and facilites time-affecting links on the child.
• Added mlt_image_full_range(const char *color_range) where any of the following strings return true (1): full, jpeg, pc.

Modules

• Added xml-clip producer.
• Fixed link in and out properties arenot serialized in the xml consumer.
• Added hslprimaries and hslrange filters to the plus module.
• Added a gradientmap filter to the plus module.
• Fixed avfilter audio filters with FFmpeg 7.
• Fixed incorrect frame rate for AVCHD (and possibly others) in avformat.
• Fixed window_id property in consumer sdl2 by using SDL_CreateWindowFrom(), especially important for embedding in GTK+ or Qt.
• Fixed text not rendering in transition vqm since Qt 6.
• Added decimals keyword to gpstext filter and move RAW keyword check.
• Fixed time_offset property handling in gpstext filter.
• Fixed reading and writing SRT files with unicode in the path.
• Fixed subtitle_feed filter on producers with an in point > 0.
• Fixed opaque alpha channels become translucent in luma transition.
• Fixed a crash in the mix transition with consumer producer.
• Fixed freeze filter freezing too much.
• Fixed avfilter.fillborders with preview scaling.
• Fixed non-proportional scaling in qtblend transition and filter.
• Fixed avfilter color distortion with mlt_image_rgb and mlt_image_rgba.
• Extended support for colorspace=2020 consumer property and the BT.2020 colorspace in the avformat producer and consumer.
  This does not imply HDR, which is signaled through a color_trc property.
• Added support for mlt_image_yuv420p10, mlt_image_yuv444p10, and mlt_image_yuv422p16 in avfilter, swscale, and rescale filters.
  This facilitates using these pixel formats end-to-end when using only FFmpeg producers, certain avfilters, and avformat consumer. This means it is possible to do 10-bit end-to-end on the CPU when being careful to select compatible components and options to avoid conversions. One can pass-through HDR; however, you must set the color_trc and pix_fmt properties on the avformat consumer (see ffmpeg -h full for these values). The avformat consumer automatically converts MLT colorspace (integer value) to FFmpeg's colorspace and color_primaries (unless explicit) options.

Other

• Cleaned up the examples in src/swig.
• Changed the x264-medium preset to a higher quality.

New Contributors

• @jonata made their first contribution in #1033
• @Integral-Tech made their first contribution in #1048
• @YakoYakoYokuYoku made their first contribution in #1046

Full Changelog: v7.28.0...v7.30.0

What's Changed

This fixes a couple of major regressions in the previous version 7.26.0:

• Fixed seeking and frozen video due by reverting "Improved performance with intra-only video and reducing the frame rate."
• Fixed using melt to render MLT XML with OpenGL effects from movit.

Other fixes and changes:

• Deprecated the composite transition and the sdl and ndi modules.
• Fixed Android camera video has the wrong frame rate (broken in v7.26.0).
• Fixed audio not playing for audio-only DTS WMA.
• Fixed using "https:" URLs in the xml producer.
• Fixed crash on exit when running melt -query or melt -query links.
• Added a transition property to the watermark filter. Now, it defaults to using affine.
• Changed affine transition argument to set rect property if supplied.