https://bugs.kde.org/show_bug.cgi?id=410726
--- Comment #3 from farid <snd.no...@gmail.com> --- (In reply to Steve from comment #1) > Created attachment 128535 [details] > an archive with 3 files that reproduce the problem > > Enclosed is a *very* simple reproduction case. Extract this archive to some > convenient directory, replace all instances of CURRENTDIR with wherever you > put the .mlt and .wav file, and all instances of PROFILEDIR with your > kdenlive profile directory. You can move the customprofile32 file there, > although I don't think it affects anything. > > Here are the parameters to mlt that I'm using: > > xml:///CURRENTDIR/audio-artifact.mlt properties=WAV -consumer > avformat:audio-artifacts.wav ar=44100 > > The .mlt file literally plays one clip with a Gain filter and a > fade-in/fade-out. It's very simple. > > At the end of the generated audio, there's a little glitch that's visible in > Audacity; it sounds like a "pop" sound. (Sometimes, my attempt to use > kdenlive to make audio for my video is filled with these artifacts, making > it unusable.) > > I spent most of today single-stepping through mlt in Qt Creator (mostly > consumer_thread() in consumer_avformat.c), inspecting memory, etc. in an > attempt to track down the source of this bug, but the audio being returned > from mlt_frame_get_audio() didn't look like the audio being output to the > .wav file, so I'm not sure how to track this. Hopefully you take this as > evidence of a good-faith effort to find the bug myself, and that someone > that knows this code better takes a look at my reproduction example. > > I noticed two odd things that might be related to the bug: > > 1) filter_get_audio(), in filter_volume.c, sets the _previous_gain property > to the current > value of "gain" at the beginning of any volume change. That seems like it > would have a > non-intuitive effect on fade-in and fade-out, i.e. a 1-frame fade-in > would actually be > a 1-frame mute followed by a 1-frame fade-in, and a 1-frame fade-out > would actually be > 1 frame of unaltered audio, followed by a 1-frame fade-out. > Since the artifact commonly happens after the clip's audio is supposed to > be faded out, > this may be related. > 2) fps values are represented by floats and doubles. NTSC framerates are > fractional, e.g. > 24000/1001 and 30000/1001 are commonly found. ffmpeg internally uses a > struct called > AVRational to avoid problems with fractional framerates. > > Please, please, PLEASE look into this! The original forum post is almost 2 > 1/2 years old, and this artifact is ruining my ability to use kdenlive. In case this is not fixed someone from the dev team will look into it. thanks for providing such useful information. :) Btw, the 20.08 cycle will see a lot of work in the audio front. See here: https://invent.kde.org/multimedia/kdenlive/-/issues/382 -- You are receiving this mail because: You are watching all bug changes.
