[gst-devel] [gst-cvs] slomo gst-plugins-bad: gst-plugins-bad/ gst-plugins-bad/ext/soundtouch/

Stefan Kost ensonic at hora-obscura.de
Thu Jan 31 20:05:57 CET 2008

Hi florent,

Florent schrieb:
>> IMHO there's no need for a special message for this. We have a BPM tag
>> and tags are send as a message too... so... :)
> Ok
>> Also the tag is sent every time the BPM changes by more than 1 and there
>> actually is a BPM value available.
> Well, what if you want to fire a graphical event (ex: light?) for
> every beat ? I'd like to sync things based on beats + bpm rate.
> * Do you think the initial bpm message + bpm measurement would be
> precise enough to sync at once (beat(t) = initial_time + time*1/bpm) ?
> * When the bpm is changing for more than 1, would the new message be
> right after a beat ?

the problem is that the algorithm used only gives you bpm estimates, it does not
tell you when the beat occured. Furthermore the plugins would need to know about
the latency to the sink then, or somehow marks the beats as payload on the
buffer it analyzed, so that the audiosink could send the message in sync with
the audio rendering. Not easy, but doable.


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