Mixxx

Deck Clone Begins Playback at Cue point

Bug #1860808 reported by Daniel Birmingham on 2020-01-24

This bug affects 1 person

Affects		Status	Importance	Assigned to	Milestone
	Mixxx	Fix Released	High	Jan Holthuis	Mixxx 2.3.0

Bug Description

OS: Manjaro Linux 18.1.5.

Debug [Main]: "Mixxx" "2.3.0-alpha-pre" "(git master r7086; built on: Jan 20 2020 @ 18:16:31; flags: asan=0 battery=1 buildtime=1 bulk=1 color=0 coreaudio=0 faad=0 ffmpeg=1 hid=1 hss1394=0 lilv=1 localecompare=1 macappstore=0 mad=1 mediafoundation=0 modplug=1 optimize=native opus=1 perftools=1 perftools_profiler=1 profiling=0 qt_sqlite_plugin=0 qtkeychain=1 shoutcast=1 test=1 tsan=0 ubsan=0 verbose=1 vinylcontrol=1 wv=0)"

Since my last build, the new Mixxx 2.3 functionality to clone a track playing in one deck to another at the rate, key, and position of the source deck is malfunctioning. Instead of matching playback on the original deck, playback begins from the cue point. Playback rate and key are copied properly. I have attached video evidence.

I'm sure the fix for this is relatively simple, and am willing to take it one with a little guidance. My first step was checking the log to see if I could identify a task that was in charge of setting the track playback location and beginning playback. It seems to me this task (playing a loaded track from some start point) does not generate identifiable debug code.

Instead I searched my local mixxx files for the "CloneFromDeck" control. This brought my attention to src/mixer/basetrackplayer.cpp. However, after examining recent changes to this file on github, I'm having trouble identifying changes that would have broken proper functionality. Thus, I guess the next step is playing around with the code myself or asking one of the admins to do it for me.

Guidance I need:
Will someone tell me or point me in the direction to learn how to properly build/install individual mixxx files such that the application will be updated so that I can test changes I make without building the whole system using Scons.

Is there other useful information you would want to know if you had never worked on a project of this scale before?

Thanks!
Dan