MLT Multimedia Framework

Author, manage, and run multitrack audio/video compositions.
The engine of a non-linear video editor that can be used in all sorts of apps, not just desktop video editors.
MLT is an open source multimedia framework, designed and developed for television broadcasting. It provides a toolkit for broadcasters, video editors, media players, transcoders, web streamers and many more types of applications. The functionality of the system is provided via an assortment of ready to use tools, XML authoring components, and an extensible plug-in based API.
Download source code. The easiest way to try out and learn MLT is by downloading Shotcut.

Recent News

v7.18.0 released

Jul 28, 2023

You can download it from GitHub.

Framework

  • Added mlt_audio_free_data().
  • Added meta.playlist.clip_position and meta.playlist.clip_length properties to mlt_playlist.
  • Fixed mlt_frame_get_audio fails on mlt_audio_none.

Modules

  • Added two audio filters to core module to be used on a playlist/track:
    • audioseam
    • autofade
  • Fixed a crash in vidstab filter on image format change.
  • Fixed font weight in qtext filter on Qt 6.
  • Fixed yuv420p not working in rescale filter.
  • Fixed text shadow outline in kdenlivetitle producer.
  • Fixed crash when changing the profile with count producer.
  • Fixed constructor corruption in frei0r module.
  • Fixed deinterlace link was added to invalid producer in xml producer.
  • Fixed producers not indicating progressive scan video:
    • kdenlivetitle
    • pango
    • qimage
    • qtext
  • Fixed video scan mode detection in avformat producers that only indicate on their container format and not on frames such as Ut Video in Matroska.
  • Fixed very large images in qimage producer on Qt 6.
  • Fixed seeking on clips that use speed_map in timeremap link.
  • Fixed a color level problem with sRGB inputs in the movit module.
  • Fixed avformat producer’s deallocation function for AVCodecContext.
  • Fixed field order of qtblend and frei0r.cairoblend transitions.
  • Changed the avformat producer seek_threshold default to 64.
  • Updated ebur128 filter to version 1.2.6.

v7.16.0 released

May 7, 2023

You can download it from GitHub.

Framework

  • Added a chain_normalizers.ini to the data directory.
  • Added New C functions to support deinterlacer links:
    • mlt_deinterlacer_name()
    • mlt_deinterlacer_id()
    • mlt_link_filter_init()
    • mlt_link_filter_metadata()
    • mlt_cache_put_frame_audio()
    • mlt_cache_put_frame_image()
    • mlt_frame_clone_audio()
    • mlt_frame_clone_image()
  • Added support for loading a filter as a link via mlt_link_filter_init().
  • Added enum mlt_deinterlacer with:
    • mlt_deinterlacer_none
    • mlt_deinterlacer_onefield
    • mlt_deinterlacer_linearblend
    • mlt_deinterlacer_weave
    • mlt_deinterlacer_bob
    • mlt_deinterlacer_greedy
    • mlt_deinterlacer_yadif_nospatial
    • mlt_deinterlacer_yadif
    • mlt_deinterlacer_bwdif
    • mlt_deinterlacer_estdif
    • mlt_deinterlacer_invalid
  • Added new 10-bit YUV members to enum mlt_image_format:
    • mlt_image_yuv420p10
    • mlt_image_yuv444p10
  • Fixed a deadlock and improved quality of start of playback when mlt_consumer property prefill is greater than 1.
  • Fixed a couple of data races in mlt_events and mlt_consumer.
  • Fixed a crash in mlt_frame_clone() with movit and the mask_start filter.

Modules

  • Fixed regressions in version 7.14.0:
    • memory and thread count usage in swresample and resample links
    • automatic profile support in melt
    • crash in count producer
  • Upgraded the glaxnimate git submodule to version 0.5.3.
  • Added avformat/avdeinterlace (default) and xine/deinterlace links.
  • Fixed deinterlacing in the multi and qglsl consumers.
  • Added 10-bit video support to movit.convert filter.
  • Several things in the avformat producer:
    • Fixed artifacts decoding raw FLAC audio.
    • Fixed a potential crash on mlt_producer_probe().
    • Fixed seeking on music with album art.
    • Fixed possible infinite loop on end-of-file.
    • Fixed a potential deadlock.
    • Fixed chroma bleeding on interlaced yuv420p.
    • Fixed color_range or force_full_range sometimes not working.
    • Fixed autorotate property not working with a chain.
    • Added audio caching.
    • Deprecated the mute_on_pause property.
  • Fixed FFmpeg version 6 compilation error.
  • Fixed rendering the text outline in kdenlivetitle producer.
  • Fixed 'movit.rect property animation.
  • Fixed corrupt video in crop filter when mlt_image_yuv420p requested.
  • Fixed possible null pointer crashes in some audio filters:
    • audiolevel
    • volume
    • loudness
  • Fixed a possible roi assert crash in opencv.tracker filter.
  • Added support for “Nano” algo to the opencv.tracker filter.
  • Added the property fix_background_alpha to the luma transition.

Other

  • Added -query links to melt command line.
  • Added avformat consumer presets for 10-bit video:
    • AV1
    • DNxHR-HQ
    • FFV1
    • ProRes 422
    • ProRes 444
    • ProRes HQ
    • x264-high10
    • x265-main10
  • Added a clang-format target to CMake and reformatted all code.
  • Added warnings as errors with some exceptions to CMake with Debug build type and gcc.
  • Fixed numerous warnings throughout the code.

v7.14.0 released

Mar 6, 2023

You can download it from GitHub.

Framework

  • Added functions to get detailed info about a producer more directly (without having to get a frame and get its image in the case of avformat producer, for example):
    • mlt_producer_probe()
    • Mlt::Producer::probe()
  • Added functions to add normalizer links to chains (based on a chain_loader.ini configuration data file:
    • mlt_chain_attach_normalizers()
    • Mlt::Chain::attach_normalizers()
  • Changed locale_t to mlt_locale_t to avoid redefinition on some systems (e.g. clang/llvm on win32).
  • Fixed the value provided with event “consumer-thread-join” to be mlt_event_data_thread as documented.
  • Fixed mlt_image_format_planes() for mlt_image_yuv420p.

Modules

  • Added a swresample link to the avformat module.
  • Added a resample link to the resample module.
  • Fixed compatibility of avformat module with FFmpeg version 6.
  • Fixed rotoscoping filter when request image size different than profile.
  • Fixed timeremap link breaking crop filter.
  • Fixed audio/video sync in avformat producer when the video start time is not 0.
  • Improved seeking on a WMA audio file in avformat producer.
  • Optimization to set AVDISCARD_ALL on disinterested streams in avformat producer.
  • Added separate demuxing thread in avformat producer.
  • Added filtergraph property to the avformat producer.
  • Fixed filter movit.convert’s CPU image converter in mlt_tractor and mlt_frame_clone().
  • Fixed using movit module with mlt_chain.
  • Fixed 10-bit full range YUV color input with Movit.
  • Fixed aspect ratio issues in qtblend filter transform.
  • Fixed the movit.luma transition.
  • Changed the qglsl consumer to use an OpenGL core profile version 3.2 context to make it compatible with recent Movit versions.
  • Upgraded glaxnimate git submodule to version 0.5.2.
  • Fixed xml producer incorrectly adds a path prefix to a consumer producer.
  • Fixed using opencv.tracker filter with mlt_chain.
  • Added interlace-aware chroma conversion from mlt_image_yuv422 to yuv420p in the avformat consumer.
  • Added the speed_map property to the timeremap link.
  • Fixed the loader producer not injecting the consumer producer when a xml producer changes the frame rate.
  • Fixed ‘loader’ producer corrupts the profile colorspace and description when it injects a consumer producer.
  • Added a loader-nogl producer to the core module based on loader but prevents adding movit-based filters.
  • Changed count producer to take an optional string argument with the name of a loader producer.
  • Fixed yadif deinterlace not working in a mlt_chain.
  • Fixed the bob, weave, greedy, onefield deinterlace filter methods on x86-64 architecture.

Other

  • Fixed SWIG python shadow functions for mlt7.
  • Added CMake build option MOD_GLAXNIMATE_QT6.

v7.12.0 released

Nov 19, 2022

You can download it from GitHub.

This version is released soon after 7.10.0 to fix a couple of major new bugs in the popular qtblend and frei0r.cairoblend transitions. It also includes new color animation APIs with sensible interpolation!

Framework

  • Added new color animation APIs:
    • mlt_property_set_color()
    • mlt_property_get_color()
    • mlt_property_anim_set_color()
    • mlt_property_anim_get_color()
    • mlt_properties_anim_set_color()
    • mlt_properties_anim_get_color()
    • Mlt::Properties::anim_get_color(char const*, int, int)
    • Mlt::Properties::anim_set(char const*, mlt_color, int, int, mlt_keyframe_type)

Modules

  • Updated the following services to support animation of color properties:
    • frei0r (any color parameter in any frei0r plugin)
    • chroma
    • chroma_hold
    • audiolevelgraph
    • audiospectrum
    • audiowaveform
    • gpsgraphic
    • gpstext
    • qtcrop
    • qtext
  • Added discontinuity_reset property to dynamic_loudness filter.
  • Fixed qtblend transition not blending with an opaque rgba image.
  • Added support for the “finer” engine in Rubberband version 3.
  • Fixed crash in frei0r.cairoblend when threads property not set.

Other

  • Fixed leaking the xml producer in melt when the XML contains a consumer element but no profile information.
  • Fixed symbol not found error in rtaudio consumer.

v7.10.0 released

Nov 1, 2022

You can download it from GitHub.

The highlight of this version is support for Qt 6.

Framework

  • Fixed some unguarded null pointers.
  • Added MLT_REPOSITORY_DENY environment variable to skip loading a module (colon delimited list of file names without extension, for example “libmltqt”).
  • Fixed frame corruption with one frame transition.
  • Changed so-called test-card frame with audio to show a checkerboard:
    • Added mlt_image_fill_checkerboard()
    • Added mlt_image_fill_white()
  • Preserve the producer creation_time property when creating a chain.
  • Added mlt_image_rgba_opaque().
  • Fixed getting a property as a timecode or clock value with 24 or 23.98 fps in mlt_property.c.

Modules

  • Added support for Qt 6:
    • Added MOD_QT6 and BUILD_TESTS_WITH_QT6 CMake options.
    • Allow installing building and installing both Qt 5 & 6 modules.
    • Avoid loading both Qt 5 & 6 modules by preferring Qt 5 (use MLT_REPOSITORY_DENY=libmltqt to block Qt 5 and use Qt 6).
    • This is limited to the qt module for now and not glaxnimate (still a work-in-progress).
  • Added support for WebP animation to qimage producer.
  • Added gps_graphic filter to the qt module.
  • Added the format property in each producer’s get_frame method to indicate the producer’s default/preferred mlt_image_format to facilitate an optimization in the qtblend transition when the B frame is opaque and has the same aspect ratio.
  • Added property animation to all audio visualization filters in the qt module.
  • Improved TGA format detection in qimage filter.
  • Fixed qtblend transition has incorrect scaling with consumer scaling.
  • Fixed an case of incorrect alpha scaling in qtblend transition.
  • Fixed luma transition not updated when resource property changes.
  • Added the alpha_operation property to the shape filter.
  • Updated the glaxnimate git submodule to version 0.5.1.
  • Fixed lines filter in oldfilm regression in v7.6.0.
  • Added dbpeak property to the audiolevel filter in dB.
  • Fixed memory leak using some frei0r plugins in conjunction with an affine that animates the rect property.

Other

  • Fixed building for musl.
  • Fixed underlinking iconv in gdk module on MinGW.
  • Fixed SWIG CMake options can overwrite each other.
  • Fixed SWIG 4 no longer generates a mlt.php.

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MLT enables you to author, manage, and run multitrack audio/video compositions.
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