v6.10.0 released

Jul 2, 2018

You can download it from GitHub.

This version fixes bugs and supports serializing animation keyframes with a specified time format (previously only frame number).


  • Reverted mlt_pool change in v6.8.0 pending further testing.
    (USE_MLT_POOL compiler define is now a 0/1 boolean, defaults to 1.)
  • Fixed crash regression in v6.8.0 “parsing non-animated string as an animation.”
  • Added pointer checks to mlt_animation.
  • Changed producer cache size heuristic in mlt_multitrack to be more liberal.
  • Fixed handling reserved characters in names for YAML in mlt_properties.
  • Added clamping to prevent computing negative in and out points to mlt_producer.
  • Added functions to serialize animation with a time format:
    • mlt_animation_serialize_cut_tf()
    • mlt_animation_serialize_tf()
    • mlt_property_get_string_tf()
    • mlt_property_get_string_l_tf()
    • mlt_properties_get_value_tf()
    • Mlt::Properties::get(int, mlt_time_format)
    • Mlt::Animation::serialize_cut(mlt_time_format, int, int)
  • Added functions to clear a property to mlt_properties:
    • mlt_property_clear()
    • mlt_properties_clear()
    • Mlt::Properties::clear()


  • Fixed enabling sliced pix_fmt conversion in avformat producer.
  • Fixed incorrect seek and sync on audio files with discard packets.
  • Added support for avcodec_send_frame() API to avformat consumer.
  • Fixed compile errors with Libav master.
  • Fixed a crash in affine transition.
  • Fixed a crash in ladspa filters when consumer frame rate is low (e.g. <= 8).
  • Fixed a crash in boxblur filter.
  • Added animation support to boxblur hori and vert properties.
  • Fixed a crash in movit.convert.
  • Fixed incorrect alpha in affine transition blending routine.
  • Converted frei0r from deprecated mlt_geometry to mlt_animation API.
  • Fixed tilde in text string for pango producer.
  • Fixed using more than one channelcopy filter.
  • Fixed the mono filter reducing volume level.
  • Fixed degraded audio scrubbing in sdl2_audio consumer.
  • Converted dynamictext filter to use affine transition for more correct alpha compositing and sub-pixel positioning.
  • Added time format support for animation keyframes to the xml consumer.
  • Added animation support to more affine transition properties:
    • fix_rotate_x
    • fix_rotate_y
    • fix_rotate_z
    • fix_shear_x
    • fix_shear_y
    • fix_shear_z
    • ox
    • oy
    • scale_x
    • scale_y
  • Fixed gaps in text when characters overlap in qtext and kdenlive producers.
  • Fixed a crash in pixbuf producer with multiple render threads.
  • Converted the oldfilm vignette filter from mlt_geometry to mlt_animation.


  • Numerous updates to mlt-xml.dtd.
  • Categorized many of the encode presets (using

v6.8.0 released

May 10, 2018

You can download it from GitHub.

This version improves support for multi-channel audio and adds some new manipulation functions to the mlt_animation API.


  • Added support for musl C library.
  • Added functions for audio channel layouts:
    • mlt_channel_layout_name()
    • mlt_channel_layout_id()
    • mlt_channel_layout_channels()
    • mlt_channel_layout_default()
  • Added channel_layout property to mlt_consumer.
  • Added mlt_channel_layout enum.
  • Disabled memory pooling by default and require compile macro USE_MLT_POOL to re-enable it.
  • Fixed reliability of keyframed properties serializing properly.
  • Fixed parsing non-animated string as an animation.
  • Added more functions to mlt_animation:
    • mlt_animation_key_set_type()
    • mlt_animation_key_set_frame()
    • Mlt::Animation::key_set_type()
    • Mlt::Animation::key_set_frame()


  • Fixed some crashes in qimage producer especially with alpha channel.
  • Fixed >2 channel audio output in the SDL consumers.
  • Fixed >2 channel audio output in the rtaudio consumer on Windows.
  • Fixed vorbis encoding with FFmpeg v3.4+.
  • qimage and qtext are now higher priority than gtk2 pixbuf and pango by the loader producer.
  • Added support for more channel counts to decklink consumer.
  • Added swresample filter based on libswresample from FFmpeg. This is now the preferred channel count normalizing filter used by the loader producer.
  • Fixed the strange “Undefined constant” and “Unable to parse option value” log messages in the the avformat consumer.
  • Fixed GIF and DPX writing in avformat consumer.
  • Reduced the memory usage of the affine transition and filters.
  • Fixed a crash in kdenlivetitle producer.
  • Fixed a crash in the rotoscoping filter.
  • Fixed frame rate reported in Matroska and WebM files produced by the avformat consumer.
  • Added sdl2_audio consumer.
  • Fixed alpha channel support for more pixel formats in the avformat producer.
  • Converted the affine transition to use mlt_rect and mlt_animation.
  • Fixed LADSPA plugins with mono channel audio.


  • Fixed a melt command line parsing bug when argument supplied to -transition.
  • Fixed melt with SDL2 on Windows not using stdio and stderr.
  • Improved speed of the vp9 avformat consumer preset.

v6.6.0 released

Jan 22, 2018

You can download it from GitHub.

This version builds upon the previous release with performance improvements using the sliced image processing framework. It also improves compatibility with dependencies (FFmpeg, Qt 5, SDL 2, NDI, OpenCV, libebur128).


  • Added a thread pool to mlt_slices:
    • mlt_slices_run_normal()
    • mlt_slices_run_rr()
    • mlt_slices_run_fifo()
    • mlt_slices_count_normal()
    • mlt_slices_count_rr()
    • mlt_slices_count_fifo()
    • MLT_SLICES_COUNT environment variable
  • Added mlt_log_timings_now() to mlt_log.
  • Added mlt_image_yuv422p16 image format.
  • Added mlt_image_format_planes() and mlt_image_format_id() to mlt_frame.
  • Added mlt_service_disconnect_all_producers() and Mlt::Service::disconnect_all_producers()
  • Fixed accuracy of mlt_time_format conversions.
  • Fixed mlt_filter_get_progress() never reaching 1.0.
  • Fixed divide by zero in mlt_filter_get_progress().


  • Added sdl2 module!
  • Added sum property to mix transition for simple mixing without dynamics.
  • Added TLD and KCF tracking modes to opencv module.
  • Added CSV (comma-separated values) simple slideshow to pixbuf producer.
  • Added jack filter to jackrack module.
  • Added sliced processing to frei0r.
  • Added sliced processing to composite transition.
  • Added sliced processing to avformat producer pixel format conversion.
  • Added sliced processing to affine transition and filter.
  • Converted volume and pan filters to floating point.
  • Added rotate_center property to qtblend transition and filters.
  • Added (VFR detection) to avformat producer.
  • Added support for external libebur128.
  • Updated internal libebur128 to latest.
  • Added 10-bit capture to decklink producer.
  • Added mlt_image_yuv422p16 to fieldorder filter, avcolour_space filter, and avformat consumer.
  • Added no_profile property to xml consumer.
  • Various ndi module fixes and improvements.
  • Fixed setting color_trc in multi consumer.
  • Fixed kdenlive title transparency.
  • Fixed incorrect alpha channel breaking freeze filter with qtblend transition.
  • Fixed transparency of pixbuf images with qtblend transition.
  • Fixed some crashes in new qtblend transition.
  • Fixed building qt module with C++11 for Qt 5.7+.
  • Fixed reporting accurage length for image sequences in qimage and pixbuf.
  • Fixed extra audio samples added to end of file in avformat consumer.
  • Fixed rawvideo export in avformat consumer.
  • Fixed multi-threading wtih FFmpeg 3.2+ in avformat module.
  • Fixed JPEG album art in avformat producer.
  • Removed filter_avresample (dropped by FFmpeg).
  • Stop flushing audio buffer in decklink consumer.
  • Fixed field order handling in decklink consumer.
  • Make composite transition field order aware.
  • Fixed nesting mlt_tractor with opengl module.
  • Fixed kdenlive titler crash on resized frame.


  • Various memory leak fixes.
  • Fixed opening files with extended chars on Windows (framework and modules).

v6.4.1 Hot-fix Release

Nov 15, 2016

There was a problem in the symbol version declaration for the new Mlt::Profile::is_valid() method that was breaking some scripting language bindings including Python. You can download it from GitHub.

v6.4.0 released

Nov 11, 2016

You can download it from GitHub. This is both a bugfix and enhancement release:


  • Added functions for multi-threaded slice-based image processing: mlt_slices_init, mlt_slices_close, and mlt_slices_run.
  • Added Mlt::Profile::is_valid().
  • Added MLT_DIRLIST_DELIMITER to mlt_types.h.
  • Renamed mlt++/config.h to mlt++/MltConfig.h.
  • Fixed mlt_properties_set_lcnumeric() on macOS.
  • Fixed address of Free Software Foundation in comment headers.


  • Added crop_to_fill property to composite transition.
  • Added sliced_composite property to composite transition.
  • Added peak and true peak properties to loudness_meter filter.
  • Added qtblend transition and filter to qt module.
  • Added ndi (NewTek NDI) module with producer and consumer.
  • Added opencv module with opencv_tracker filter.
  • Added line_spacing, strech, wrap_width, and wrap_type properties to pango producer.
  • Added oblique value for style property to pango producer.
  • Added fontmap-reload event to pango producer.
  • Added support for pkg-config to sdl module.
  • Added .kra (Krita Image) file name extension to loader.dict.
  • Improved performance of kdenlivetitle producer.
  • Improved decklink producer and consumer.
  • Improved accuracy of seeking on lossy compressed audio in avformat producer.
  • Improved mix transition using 32-bit floating point.
  • Fixed avfilter when image format changes.
  • Fixed loading relative file name in vidstab filter.
  • Fixed crash on Windows with avfilter.
  • Fixed parsing LADSPA_PATH with semi-colon delimiter on Windows.
  • Fixed parsing FREI0R_PATH with semi-colon delimiter on Windows.
  • Fixed reading relative path with backslash (Windows) in xml producer.
  • Fixed loading relative file name for av.file (avfilter).
  • Fixed loading multiple LADSPA plugins on some systems.
  • Fixed compile error when not configured with –enable-gpl.
  • Fixed loading in avfilter.lut3d in locales with comma decimal point.
  • Fixed a possible crash in resample filter.
  • Fixed alpha channel in kdenlivetitle producer.
  • Fixed possible crash in pixbuf and qimage producers.
  • Fixed count when counting down in count producer.


  • Moved some avformat presets from lossless to new intermediate folder.
  • Added a YouTube avformat consumer preset.
  • Changed metadata.rb metadata publisher to output Markdown.



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