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(update) skipping audio

PostPosted: 07 Dec 2014, 14:45
by carmatic
previously :
hello, sometimes the automatic beat detection does not correctly determine the BPM of a track, hence I have to manually edit the beatgrid so that it aligns with the audio

this is a time consuming process but it produces acceptable results

however, the next time I load the same track, the beatgrid is the incorrect one that has been automatically generated by CrossDJ, and I have to manually align the beatgrid to the audio again, and this makes it unproductive to play that track in a set

is there a way to save the edits I have made to the beatgrid?

upon further testing, it seems that Cross DJ has an issue with some music files, particularly VBR MP3 files, resulting in skipping audio. the audio will playback correctly when simply playing from the beginning, but when you jump to a different point in the audio, the skipping will occur, and this throws the audio off from the beatgrid , it is visible as small gaps of silence in the audio in the waveform view
the skipping seems to be at random

Cross DJ also seems to utilize some sort of 'cache', whereby the corruption of the audio is preserved even when you close the app, open it and load the same track again

Re: saving beatgrid edits?

PostPosted: 07 Dec 2014, 16:12
by RoJeC
It's supposed to be saved.
Are you using any syncing for your track files.

If not what's your device and the app version etc.

Re: saving beatgrid edits?

PostPosted: 07 Dec 2014, 16:54
by carmatic
hi, upon exiting and restarting CrossDJ, I find that the beatgrid is indeed saved

however, upon a little bit more testing, it seems that if you touch the graph at the top section to skip to a section of the track, it will be aligned... but if play the track, or simply scroll forwards or backwards, it drifts out of sync with the beatgrid

I use syncing to beatmatch my tracks, and I am using version 2.0.1

Re: saving beatgrid edits?

PostPosted: 07 Dec 2014, 19:25
by RoJeC
Ok. With syncing i ment syncing of files, not the audio function.

Re: (update) skipping audio

PostPosted: 09 Dec 2014, 13:51
by carmatic
I have found the reason for the beatgrid 'drift' : the audio is actually skipping in the tracks where I thought the beat detection has failed, where in reality the beat detection was correct... the problem is triggered by starting playback from a point other than the beginning of the track, and the skipping throws the audio out of alignment from the switching to the waveform view, seemingly random small gaps in the audio can be seen after a jump operation
these gaps/skips only seem to happen for around the next 10 seconds after the start of playback, but by scrolling the track backwards past a certain point, it causes regular skipping... these skips basically follow where you jumped to on the track
my mistake has been to try and align the beatgrid manually and jumping to different parts of the track to check that the beatgrid aligns consistently, when the problem was caused by the act of jumping around the track

switching between the default and google decoders, between fast and normal, changing the OpenSL mode from async to sync doesn't make any difference

Re: (update) skipping audio

PostPosted: 15 Dec 2014, 00:53
by carmatic
I have found the source of the problem : tracks longer than 10 minutes

There is a track in my collection which is 9:59 , if you go into waveform view,jumping around by touching on the track overview at the top causes the waveform to update instantly, with the audio snapped to the beatgrid

However, any tracks which exceed 10 minutes will exhibit a different behaviour... Jumping around the track would cause the waveform view to 'regenerate' i.e. the waveform only appears after a delay , and there will be skips in the audio before and after, and audio is no longer aligned with the beatgrid