How to play a sound in the middle of the sound?

Help with Snap!
1

(I can't leave a project cause apparently a two-measure song split into 4 parts.)
I would like to manually cross-fade instruments together into a song. How do you start a sound in the middle of the sound? Also is there a way to track where you are in a sound you're playing so I can sync them up?

Edit: BTW I mean media, not MIDI.

2

image

3

Wow. That is interesting. Thanks!

4

No need for JavaScript here. Just get rid of the first (seconds * sample rate) samples of the sound.
play sound n seconds in

5

It didn't work. I'm getting
"Failed to execute 'createBuffer' on 'BaseAudioContext': the number of frames provided (0) is less than or equal to the minimum bound (0)."

6

That means you're trimming off all the samples in the sound. Either seconds is too high, or there's some other mistake.

7

Actually, I'm looking at the code. It doesn't make sense. Why do you multiply seconds by sample rate? That just gives 44100.

8

Sound is a wave. It has an amplitude, which is a positive or negative "height" that varies over time. Storing the exact shape of this wave is impractical, so digital sound is stored as a list of samples, which tell you the magnitude at specific points of time, separated by a fixed interval:

Signal_Sampling
Signal_Sampling1107×718 31.2 KB

Usually, samples are recorded every 1/44100 seconds, and taking the inverse of this interval gives you the sample rate of 44100 hertz (samples per second). So when you want to get rid of the first N seconds of a sound, you multiply N by the sample rate, and that tells you the number of samples you need to remove from the beginning of the sample list.

9

So if I want to start 1 second in, I remove 44100 samples. That makes sense.
But why doesn't this work?

Adaptive Sound Project script pic
Adaptive Sound Project script pic944×408 72.2 KB

It should have 6 seconds length.

10

Nvm I guess it doesn't matter anyway. It'd be nice to know, but I can't track the position within the song anyway, so I'd have to use the JS. I got it to work with that. Thanks!
As a side note... I have a function borrowing code from parallel running scripts and used [launch] to start a loop in a function.

Adaptive Sound Project script pic begin loops
Adaptive Sound Project script pic begin loops970×1046 152 KB

But... I can't use messages to [stop loops] in a different block since message retains the original broadcast. How else would I do this. (I'm doing it in here so I don't have a million topics for one project.)

11

Alright, I forgot to account for sounds with more than one channel. For sounds with one channel, the samples block gives you a list of samples, but for sounds with more than one, the block gives you a list of lists of samples.

This is getting too complicated just for screenshots so I've shared an example here: https://snap.berkeley.edu/snap/snap.html#cloud:Username=djdolphin&ProjectName=sound%20trimmer

12

Thanks!