Hey Thomas,
That was really helpful. It now safely works for all sampling rate. Though
not spot on at 1:00:00 because of some approximations in rendering the
waveform. Nonetheless I can safely say the patch makes no assumptions,
except that tracks must be under 50 :D minutes. Thanks again for the useful
reply. I have uploaded the patch in the bug discussion.
Thank you,
Akash. Shetye.
On Thu, Feb 9, 2012 at 7:00 PM, thomas vincent <[email protected]> wrote:
> Hi there,
>
> I thinks this is great to dig into mixxx code to contribute, go ahead !
>
> To find the relationship between actual timing (here 1:00:00) and
> sample position you have to involve the "sampling rate".
> For example in the most common case of a sampling rate of 44100 Hz
> (means sample per second) of a stereo song (left and rigth channel)
> your have :
>
> numberOfChannel x samplingRate x oneMinuteInSeconde =
> numberOfSampleInOneMinute
> 2 × 44100 × 60 = 5292000
>
> Witch is roughly what you "found".
> I hoping it makes sense ... :)
>
> vrince
>
>
> 2012/2/9 Akash Shetye <[email protected]>:
> > Hey,
> >
> > Thank you Albert for that one or I would have still been going in
> circles.
> > College has been keeping me busy off late.I have managed to get the patch
> > working fine and it looks great. But I still have these questions.
> >
> > It seems that the track is converted into frames and these frames then
> are
> > processed, so there seems to be no way for me (so far) to know at which
> > frame number will the minute 1:00:00 lie on.
> >
> > However by some simple qDebugs I have figured out that it lies on the
> > position apprx 5292846. Its isn't exactly at 1:00:00 but it gives a
> > tolerable performance deviating in the worst cases by 00:59:30-88. Even
> if
> > it seems to work exactly like we intend it to, I do not want to base the
> > patch entirely on an approximate observation. Can anyone tell me about a
> way
> > to actually relate the 1:00:00th moment in a track with its position.
> Well
> > it is also true that the markers will be approximate representation and
> will
> > never be used as exact references by any DJ.
> >
> > The code done so far works good and is optimized to save long
> calculations.
> > Following is the code that find out the minute markers. Its done in
> setData
> > of WOverview, so it is calculated only once for each song.
> m_minuteArray is
> > a float array of size 50 and stores the paint.drawLine(fPos, 0, fPos,
> > height()); ----- fPos values directly instead of calculating them in
> paint()
> > again and again.
> >
> >
> > long oneMinute = 5292846;
> > for(int i = 0; i < 50; i++){
> > if(oneMinute < m_liSampleDuration && oneMinute >= 5292846){
> //
> > Addition may cross long limit, such must be detected too
> > m_minuteArray[i] = float(oneMinute) *
> > (width()-2)/m_liSampleDuration;
> > oneMinute = (long)(oneMinute + 5292846);
> > }
> > else{
> > m_minuteArray[i] = 0;
> > }
> > }
> >
> >
> > If you are reading this, thank you for your time ;)
> >
> > Akash. Shetye
> >
> >
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> >
>
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