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

v7.28.0 released

Sep 12, 2024

You can download it from GitHub.

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.

v7.26.0 released

Aug 25, 2024

You can download it from GitHub.

This release adds support for subtitles and LV2 & VST2 audio plugins.

Framework

  • Fixed a double-free crash in Mlt::Service::profile().

Modules

  • Fixes and improvements to the avformat producer:
    • Changed to prefer r_frame_rate over avg_frame_rate.
    • Fixed lowres if set too high.
    • Fixed audio_index=all.
    • Fixed variable_frame_rate incorrectly set true on 59.94 fps in Matroska.
    • Improved performance with intra-only video and reducing the frame rate.
    • Fixed mono audio handling regression on FFmpeg 7.
    • Fixed audio samples may be dropped unexpectly esp. with uncompressed.
  • Fixed movit transitions with a non-movit filter on one of its inputs.
  • Fixed duration in the glaxnimate producer off by one frame.
  • Added dropshadow filter to the qt module.
  • Fixed resetting animation in kdenlivetitle producer.
  • Added support for LV2 and VST2 plugins in the jackrack module.
  • Fixed crash using av.declick audio filter on FFmpeg 7.
  • Added subtitle filter and producer and subtitle_feed filter to the plus module.
  • Added subtitle encoding to the avformat consumer (new properties beginning with “subtitle.”).
  • Fixed alang in the the avformat consumer.
  • Added #gps_power keyword to the gpstext filter.
  • Fixed tab handling in the kdenlivetitle producer.

Other

  • Added 8- and 10-bit encode presets for SVT-AV1.
  • Fixed building on OpenBSD.
  • Fixed building on musl libc.
  • Fixed consumer properties not updating the automatic profile on the melt command line.
  • Added -loglevel command line option to melt.

v7.24.0 released

Apr 27, 2024

You can download it from GitHub.

The highlight of this release is support for FFmpeg 7 and Ambsonic audio.

Framework

  • Fixed a small memory leak in mlt_repository.
  • Fixed a small memory leak in MltPushConsumer C++ class.
  • Block connecting a null producer to a service.
  • Include locale.h on any GNU libc platform.

Modules

  • Added a new spatialaudio module with filters:
    • ambisonic-decoder
    • ambisonic-encoder
  • Fixed building with FFmpeg 7.
  • Fixed text keywords do not work with non-ASCII filenames on Windows:
    • pixbuf producer
    • opencv_tracker filter
    • dynamictext filter
    • qimage producer
  • Added “meta.media.aspect_ratio” property to the avformat producer.
  • Fixed distort property not working in movit.rect filter.
  • Fixed frames dropping or repeating in the multi consumer.
  • Fixed the dynamic_loudness filter maximizing audio gain.
  • Fixed distortion in the mono filter.
  • Also check for WAYLAND_DISPLAY to detect a graphical session in the qt and glaxnimate modules.
  • Fixed the wave filter distorts if wave = 1 with preview scaling.
  • Added the read-only meta.media.%u.codec.layout property to avformat producer.
  • Set the channel_layout property on the frame for the noise and tone audio producers.
  • Fixed outline maximum for the text and dynamictext filters.

Other

  • Fixed crash when using -chain from melt.
  • Fixed a small memory leak on Windows fopen().

v7.22.0 released

Nov 28, 2023

You can download it from GitHub.

The highlight of this release is support animation easing functions via new keyframe types. Also, new versions of the smooth keyframe type is added that avoids overshoots and cusps.

Framework

  • Added new functions:
    • mlt_property_is_color()
    • mlt_property_is_numeric()
    • mlt_property_is_rect()
  • Many new keyframe types:
    • mlt_keyframe_smooth_loose - ~= (same as old mlt_keyframe_smooth - Unity Catmull-Rom spline)
    • mlt_keyframe_smooth_natural - $= (Centripetal Catmull-Rom spline with natural slope)
    • mlt_keyframe_smooth_tight - -= (Centripetal Catmull-Rom spline with 0 slope)
    • mlt_keyframe_sinusoidal_in - a=
    • mlt_keyframe_sinusoidal_out - b=
    • mlt_keyframe_sinusoidal_in_out - c=
    • mlt_keyframe_quadratic_in - d=
    • mlt_keyframe_quadratic_out - e=
    • mlt_keyframe_quadratic_in_out - f=
    • mlt_keyframe_cubic_in - g=
    • mlt_keyframe_cubic_out - h=
    • mlt_keyframe_cubic_in_out - i=
    • mlt_keyframe_quartic_in - j=
    • mlt_keyframe_quartic_out - k=
    • mlt_keyframe_quartic_in_out - l=
    • mlt_keyframe_quintic_in - m=
    • mlt_keyframe_quintic_out - n=
    • mlt_keyframe_quintic_in_out - o=
    • mlt_keyframe_exponential_in - p=
    • mlt_keyframe_exponential_out - q=
    • mlt_keyframe_exponential_in_out - r=
    • mlt_keyframe_circular_in - s=
    • mlt_keyframe_circular_out - t=
    • mlt_keyframe_circular_in_out - u=
    • mlt_keyframe_back_in - v=
    • mlt_keyframe_back_out - w=
    • mlt_keyframe_back_in_out - x=
    • mlt_keyframe_elastic_in - y=
    • mlt_keyframe_elastic_out - z=
    • mlt_keyframe_elastic_in_out - A=
    • mlt_keyframe_bounce_in - B=
    • mlt_keyframe_bounce_out - C=
    • mlt_keyframe_bounce_in_out - D=
  • Fixed missing support for mlt_service_transition in Mlt::Producer() C++ constructor.

Modules

  • Fixed rotoscoping filter crash on image with height = 0.
  • Fixed crashed due to qtblend transition requesting an image of 0 width or height.
  • Added support for RtAudio 6 in the rtaudio consumer.
  • Fixed createdate keyword deletes preceeding text in dynamictext filter.
  • Added opacity property to filters that use qtext:
    • dynamictext
    • gpstext
    • qtext
    • timer
  • Added fade_video, fade_audio, and fade_color properties to autofade filter.
  • Added backwards compatibility for changed filter names in frei0r v2.3.1:
    • frei0r.measure_pr0be
    • frei0r.measure_pr0file
    • frei0r.tehroxx0r
    • frei0r.alpha0ps_alpha0ps
    • frei0r.alpha0ps_alphagrad
    • frei0r.alpha0ps_alphaspot
    • frei0r.denoise_hqdn3d
  • Fixed a memory leak in avformat producer with consumer deinterlacer=yadif.
  • Fixed qimage producer color if consumer color_range=pc pix_fmt=yuv444p.

Other

  • Fixed ten_bit/ProRes 422 avformat preset produced ProRes 444.
  • Fixed YouTube avformat preset did not output high profile with some hardware encoders.

v7.20.0 released

Oct 1, 2023

You can download it from GitHub.

Framework

  • Fixed “blank” in a playlist does not have audio normalization filters.
  • Fixed serializing mlt_color transparent black as “#00000000” when the property was set using an integer or mlt_color.
  • Fixed mlt_chain_set_source() would always fetch a frame from the producer even if it has “meta.media.frame_rate_num” and “meta.media.frame_rate_den” properties making things slow.
  • Fixed Mlt::Chain leaking memory.

Modules

  • Added a blank producer to the core module.
  • Added keywords to gpstext filter:
    • #gps_cadence#
    • #gps_grade_degrees#
    • #gps_grade_percentage#
    • #gps_temperature#
  • Added some color_styles to the gpsgraphic filter:
    • 10 = color by speed (max 100 km/h)
    • 11 = color by grade (max 90 degrees)
    • 12 = color by grade (max 20 degrees)
  • Added more unit formats to legend_unit property of gpsgraphic filter:
    • mmin or m/min
    • ftmin or ft/min
  • Added keywords to dynamictext filter:
    • #basename#
    • #filename#
  • Fixed installing filter_audioseam.yml.
  • Added an avlink link to the avformat module for FFmpeg filters that can benefit from future frames such as adeclick.
  • Added the preserve_alpha property to the box_blur filter.
  • Fixed loading service metadata for the qt6 and glaxnimate-qt6 modules.
  • Fixed a crash when changing the rotate property in avformat producer with interlace video.
  • Add astream and vstream properties to avformat producer. Unlike audio_index and video_index are absolute indices across the entire array of streams regardless their type, these new 0-based properties are relative to the type audio or video. For example, astream=1 is the second audio stream.
  • Fixed a possible crash in the avformat producer’s mlt_producer_probe virtual function.
  • Updated the glaxnimate module to version 0.5.4.
  • Fixed the sdl2 consumer crashing with the Linux radeonsi_dri driver and showing only all black with the Linux nvidia driver.

Other

  • Fix compiling on Android (not supported by the core developers).
  • Changed the avformat consumer FLAC preset to use the flac format.
  • Fixed the melt Shift+H and Shift+L keyboard shortcuts when the SDL2 window has focus.

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