Hi Андрей
I am not sure if I am competent enough, so I have send this mail to
mixxx-devel as well.
Maybe someone else can give hints what are the pros and cons.
Here some facts:
Mixxx currently read 2 * 65536 Samples ahead. This is 1,5 s @ 44.1 kHz
see:
https://github.com/mixxxdj/mixxx/blob/master/src/engine/readaheadmanager.cpp#L156
Mixxx uses 5MiB = 60 s @ 44.1 kHz cache per deck.
see: https://github.com/mixxxdj/mixxx/blob/master/src/cachingreader.cpp#L16
I have node made further investigation, but I think an other moving read
ahead point with a gap to the current might stress the sound sources much.
How far is the most realistic beat jump? If you want to jump 16 beats in
both directions @ 90 bpm we need 22 s cache for this. So we might might
want to read 15 chunks ahead?
Kind regards,
Daniel
2013/8/19 Андрей <x...@xorik.ru>
> Hi Daniel!
>
> I very want to make beatjump feature in mixxx (jump over nth beats
> forward or backward without out of sync). This is VERY needed feature on
> live mixes.
>
> Long time ago I'll try to do all calculations in javascript, but it's
> not worked correct ( https://bugs.launchpad.net/mixxx/+bug/990976 )
>
>
> Now I want to try make native engine function for beatjumps, for using
> it in the JS.
> E.g. beatjump(-16) - jump over 16 beats backward.
>
> So I want to ask you: how can I start to do this? I was noticed, we have
> hint class for loops, to read music data from disk. I think there may be
> some problems (because we don't know when user want to beatjump and how
> many beats will be this jump). I think we can store in memory closest
> song part (ege +/- 1 min from current position), or even store all song
> in memory (if user have big RAM amount).
>
> Another way to do this is use two functions, eg. setBeatjumpLength( int
> len ) and second: doBeatjump( bool forward ).
>
> In this case we exactly knows where user can jump in each moment.
>
> What you think about this?
>
>
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