Auto DJ: issue when changing decks' crrossfader assignment

[Eve00000]

Bug Description

AutoDJ uses the crossfader to pass the audio signal. When AutoDJ is enabled the crossfader starts to move. When AutoDJ is disabled the crossfader stays 'in position". When using AutoDJ as Backup for going to the bathroom this is not 'handy'
If internal mixer 'and crossfader are hidden in settings (working with external mixer, each deck a channel) crossfader must be reset to the center (settings - display mixer .....)
Correct me if I'm wrong but there is no way to disable the crossfader (and internal mixer)
When I put the little knobs under the hliders in the mixer on 'center' AutoDJ won't start because AutoDJ wants a deck on each side of the crossfader.
When setting deck3 to leftside and deck4 to right side while deck 1 & 2 are centered AutoDJ starts using Deck 3 & 4 for a couple of seconds and then causes mixxx to crash.

Version

2.5

OS

Win10 / Win 11

[ronso0]

AutoDJ uses the crossfader to pass the audio signal. When AutoDJ is enabled the crossfader starts to move. When AutoDJ is disabled the crossfader stays 'in position". When using AutoDJ as Backup for going to the bathroom this is not 'handy'
If internal mixer 'and crossfader are hidden in settings (working with external mixer, each deck a channel) crossfader must be reset to the center (settings - display mixer .....)
Correct me if I'm wrong but there is no way to disable the crossfader (and internal mixer)

That's how it is: AutoDJ works with the crossfader.
What exactly are you proposing?
(note there is #11571 and it's Pros and Cons have been discussed at lengths, just someone has to implement it)
(note there is #7520 Volume slider mode for Auto DJ)

[ronso0]

When setting deck3 to leftside and deck4 to right side while deck 1 & 2 are centered AutoDJ starts using Deck 3 & 4 for a couple of seconds and then causes mixxx to crash.

Will try to reproduce.

[Eve00000]

Hi Ronso, thank you for responding.
I will answer in general. I think Mixxx became to much a 'complete DJ solution for bedroom-DJ's with low budget in the 2020's'.
In My Honest Opinion (as you all use IMHO here) the basic values and necessities of a DJ are lost or unknown.
Why do/did people go to clubs, discotheques, fectivals etc? Because they want to hear 'new music' in the best possible quality on the best possible audio-installation.
It all starts with the source, how can you produce HQ audio when playing 320kb MP3's (Sometimes I hear people playing 96 or even 72, you should hear the quality difference with (my) 24bit 96Khz, or even see what a speaker does ... the difference is huge). In the days (yes long ago) we bought 45rpm Singles (or MaxiSingle) to have a song, if it wasn't available we bought the LP or later the CDS/CDM or full CD. DJ-ing was an expensive hobby, if you could earn some money with it, you had to invest it in new material. You could be searching months for a certain track.
And music was expensive at the time. A hard to get track could cost 10 to 50 times the regular price.
Nowadays people want music for free but what you get for free is .... of doubtful quality.
Even the hardware. In the clubs or party-venues was the DJ-equipment (if there was some) most of the time ruined by people not nowing what they did. When letting a sound & light company install the hardware could also give hardware with a problem. So we were talking our own hardware with us. I've had 4 sets of Technics SL1200 MK...,Denon Dual CD-Players, Pioneer CDJ's and at least 10 mixers. When a glider or potmeter produced a little crack it had to be checked and repaired. We always had backup material with us: extra mixer, extra recordplayers, needles, cd-players and computers (sampling, copy of rare tracks in WAV).
DJ-ing was equal on filling a van (boxes full of records, cd's, hardware..)
In the late 90's I started using BPM Studio as a 'digital recordbox', huge PC in a huge flightcase, RME controller, diskarray of 10 SCSI Disks of 50GB because all tracks were in WAV and diskspace was rare and expensive. I could made the switch because of a controller and the Timecode-vinyl. And a backup PC (off course).
We take care of quality, my connection cables between soundcards and mixers are goldplated, connections with amplifiers are always done with balanced XLR. cables that cost more then the toycontrollers people use.
What do you need nowadays? What are the investments? Just a basic PC. The software and music can be found at no expenses. But so is the quality.
What does Mixxx want to be?
A tool or toy?
A tool for (mobile) DJ's giving people a good time and HQ service (New Music in HQ, HQ PA, preferable HQ mixxxing) where people mostly pay for (ticket or price of drinks), they also want to feel the music. (can't achieve that with mp3)
or a toy for bedroom/livingroom-wannabees that don't care what software they use as long as it is free and that can work with the plastic box they received from Santa Claus.
I don't think Mixxx can be both.
If it is a real tool for DJ's than the mixer / effects etc is not hat important. Important is that the program is stable, doesn't use to much cpu, doesn't make strange noises, plays at the normal speed, pitching, scratching, etc must be reliable. If BPM/Key detection is offered it must be reliable.
That is the most important word in my expliqée: RELIABILITY
Occasionally I see someone towing around with a big all-in-one Pioneer-controller putting it asides professional material and trying to connect his controller to the main-mixer resulting in a noisy sound.
The whole mixer / crossfader / effectrack etc is for bedroom/livingroom use, I don't want to offend people but that's what it is.
I don't want and I will never use it, I'm happy with the stable players, even that is nowadays not anymore that easy.

What I would really like? The possibility to disable what I don't use., the internal mixer fi and more attention for things that are really important: stability, protection against stupidity (ejecting a playing track or AutoDJ putting the invisable crossfader to the other site. ). And the toys? I'll get the effects from an external effect-cpu with send-receive from the mixer.
Sorry ronso, you asked what I was proposing.

[ronso0]

When setting deck3 to leftside and deck4 to right side while deck 1 & 2 are centered AutoDJ starts using Deck 3 & 4 for a couple of seconds and then causes mixxx to crash.

1 I tried this

• decks 1/2 --|--, 3 |----, 4 ----|
• start AutoDJ
• uses decks 3/4
• deck4 playing, deck3 stopped
• make deck1 |----
• click Fade Now
• ⚠️ "AutoDJ requires two decks at the opposite side of the crossfader", AutoDJ turns OFF

2 and this

• deck3 |----, deck1 --|--, deck2 ----|, deck4 ----|
• start AutoDJ, plays deck3
• Fade Now
• fades to deck2
• uses decks 3 + 2 without issues
• while deck3 is paying: set deck --|-- (should switch to deck4 which is still ----| )
• ⚠️ "AutoDJ requires two decks at the opposite side of the crossfader", AutoDJ turns OFF

So there is definitely something to improve in the deck attributes logic.

[Eve00000]

video: sorry for the music, just testing at home
The crossfader error was not that bad, I just missed a mix ;-)

PS: I added "m_pCOCrossfader->set(0);" at line 580 in src/library/autodj/autodjprocessor.cpp.
My Mixxx is getting very peronal now. :-(

[ronso0]

When you say "crash" you probably hit this debug assert

DEBUG ASSERT: "pFromDeck && pToDeck" in function void AutoDJProcessor::calculateTransition(DeckAttributes*, DeckAttributes*, bool) at ./src/library/autodj/autodjprocessor.cpp:1233
[1]    33203 abort (core dumped)  ./mixxx --developer --settingsPath /home/ronso/.mixxx_dev

Mixxx 2.5 is still alpha, i.e. like beta it is built with DEBUG_ASSERTIONS_FATAL set ON (unless you changed that setting, please verify).
So this is not a "crash" (entirely unhandled exception with Mixxx being unable to deal with it) but a helper that indicates that code path should be improved.

[Eve00000]

No it is another:
DEBUG ASSERT: "beatFraction > 0 && beatFraction < 1" in function bool __cdecl mixxx::Beats::findPrevNextBeats(class mixxx::audio::FramePos,class mixxx::audio::FramePos *,class mixxx::audio::FramePos *,bool) const at D:\mixxx-main\src\track\beats.cpp:415

I know it's alpha, but by using and testing I can help finding bugs. By using a release we're not getting further.

[ronso0]

Can you reproduce this hit?

[Eve00000]

Yes, the video is the 7th time or so.... I wrote it in my original post. How many times you want it reproduced? Don't let me make a video each time :-)

[ronso0]

I know it's alpha, but by using and testing I can help finding bugs

Yep, thanks for that. I wanted to point out it's not crashing, in this case (release, FATAL Off) the function simply returns.

How many times you want it reproduced?

Are wa talking about the same assert here? I meant: can you reporduce the assert hit in beats.cpp:415 with the described test procedure AutoDJ?

In general I'm mostly working mobile, so for saving bandwidth/volume I prefer some simple repro steps over a 5min FullHD video, which also way more convenient for anynone passing by ; )