Develop Reference

p5.sound distord sound on mobile?

I'm developing an experimental website which uses p5.sound to analyze a certain song and I use the frequencies of this song to draw on a canvas.
The problem is that the sound sounds great on my laptop & pc, but when I try to listen it on mobile, it's starting to flicker, having noisy parasites and it's slowed down (a lot...)
I've tried on others phones and it's the same.
Even on the official doc : https://p5js.org/examples/sound-sound-effect.html
it's laggy for a simple ring sound.
Does anyone experienced this issue?
It's working fine if I use regular JavaScript and html <audio> elements.
Also, do you know others simple ways to get frequencies of a sound played from html <audio> elements?

So I found the solution by actually look how p5.sound was working.
I ended up using the Web Audio API.
I created an audio context then an analyser and the sound was no longer distorded on mobile.
The process is almost the same as if you where using p5 :)

jPlayer not looping properly?

I'm trying to create an audio playlist with jPlayer that will preload the next song in the list for seamless transitions, but I'm having some trouble with the looping feature.
I've got my code set up here: http://jsfiddle.net/Mz74e/
It uses 2 different players in order to preload the clips. The graphic UI is just shown for debugging, since I don't plan on using it in my final setup.
The current setup seems to loop properly in Firefox 12 and the flash player, but doesn't in Google Chrome 18 (It just goes to the beginning of the clip and sits there)
If anyone can look at how I'm using it and either figure out a workaround of a better implementation, that would be great!

Turns out that the problem was not where I originally though it was.
This exact same code works fine if the audio file is statically served by the web server.
I found this code here for the rangeDownload function:
http://mobiforge.com/developing/story/content-delivery-mobile-devices
Using this, the files are distributed properly to be played by html5.

Gapless Transition from Video to Video using html5

I am trying to create a feature where a user can change (back and forth) between multiple videos while maintaining a single consistent audio. Think of being able to watch a concert from multiple angles but listening to a single audio. The trouble I am having with this feature is that there can not be a lag between the changes in video or the audio will no longer sync with the videos (especially true after multiple changes).
I have tried two methods, both using html5 only (I would prefer not use flash although I will eventually have a fallback) that have not worked seamlessly, although depending on the browser and hardware, it can come very close.
Basic Methods:
Method 1: Preloading all videos and changing the video src path on each click using javascript
Method 2: Again preloading video and using multiple tags and changing between them using javascript on each click.
Is there anyway to get either of these two methods to work seamlessly without a gap? Should I be using a slight of hand trick, like playing both videos concurrently for a second before revealing the second and stoping the first? Can this just not be done with html5 players? Can it be done with flash?
I have seen this type of question a couple of times with both video and audio with no clear solution, but they were a couple of months old and I was hoping there is now a solution. Thanks for the help.

Worth adding that it is possible with the MediaSource API proposed by Google. This API allows you to feed arbitrary binary data to a single video element, thus if you have your video split into chunks you can fetch those chunks via XHR and append them to your video element, they'll be played without gaps.
Currently it's implemented only in Chrome and you need to enable Enable Media Source API on <video> elements in chrome:flags to use it. Also, only WebM container is currently supported.
Here is an article on HTML5Rocks that demonstrates how the API works: "Stream" video using the MediaSource API.
Another useful article that talks about chunked playlist: Segmenting WebM Video and the MediaSource API.
I hope this implementation gets adopted and gets wider media container support.
UPDATE JUN 2014 Browser support is slowly getting better: (thanks #Hugh Guiney for the tip)
Chrome Stable
FF 25+ has a flag media.mediasource.enabled [MDN]
IE 11+ on Windows 8.1 [MSDN]

Did you find a better way to do that?
I implemented a double-buffered playback using two video tags.
One is used for the current playback, and the second for preloading the next video.
When the video ends I "swap" the tags:
function visualSwap() {
video.volume = video2.volume;
video2.volume = 0;
video.style.width = '300px';
video2.style.width = '0px';
}
It has some non-deterministic behavior, so I am not 100% satisfied, but it's worth trying...

Changing the SRC tag is fast, but not gapless. I'm trying to find the best method for a media player I'm creating and preloading the next track and switching the src via "ended" leaves a gap of about 10-20ms, which may sound tiny, but it's enough to be noticable, especially with music.
I've just tested using a second audio element which fires off as soon as the first audio element ends via the event 'ended' and that incurred the same tiny gap.
Looks like (without using elaborate hacks) there isn't an simple(ish) way of achieving gapless playback, at least right now.

it is possible. you can check this out: http://evelyn-interactive.searchingforabby.com/ it's all done in html5. they are preloading all videos at the beginning and start them at the same time. didn t had time yet, to check how they re doing it exactly, but maybe it helps if you check their scripts via firebug

After many attempts, I did end up using something similar to Method 2. I found this site http://switchcam.com and basically copied their approach. I pre-buffered as the video start time approached and then auto-played as the videos starting point hit. I had the current videos playing simultaneously (in a little div - as a UI bonus) and users could toggle between the videos switching the "main screen view". Since all videos were playing at once, you could choose the audio and the gap didn't end up being an issue.
Unfortunately, I never ended up solving my problem exactly and I am not sure my solution has the best performance, but it works okay with a fast connection.
Thanks for everyones help!

Multi-channel audio support in the browser on iOS and Android

I found this link to a page here on StackOverflow about "Creating Audio using Javascript in <audio>", and this page on how to play audio on multiple channels. I found that the iPhone supports the audio tag and the Audio object in Javascript to play single channel audio, but is there a way to play audio on multiple channels?
Maybe I'm over complicating this, so this is what I'm trying to do. I want a way to make a graceful audio player in Javascript that supports transitioning from one audio file to another. The way I was going to implement this is to incrementally reduce the volume on one channel while incrementally increasing the volume on the other channel so I'd get a kind of fade effect. Is there a simpler solution to this using only Javascript? I guess another solution would be to reduce the volume to a certain point, start the new audio file on the same channel, then increase the volume again. This circumvents the need for fading, but I would like to fade if at all possible.
Is this possible? I know the HTML5 spec isn't finished yet, but is there some kind of workaround that you know of? Do any of you have ideas for another approach?
From what I can tell from this post about playing audio in the Android browser, this isn't supported yet, but do any of you know if it will support multiple channel audio once the audio tag is supported? Does opera mini support this?

This is an old question I know :).
iOS Safari does not support multiple audio objects playing at the same time. Also, it is not possible for having a fade-in/out effect for iOS, as the only way to change the volume setting is from the hardware itself. Apple decided to give this ability only to the device user. Volume setting is not writable by javascript. It is not even readable (always returns 1).
You can check out the Safari documentation for iOS for more info.
For Android, to be honest I have no idea.

There's no direct way that I know of to have multiple channels on an audio tag, but check out this blog post on using multiple audio tags to simulate multiple channels. http://www.storiesinflight.com/html5/audio.html

I know this is a total hack but try this trick I came up with...
Go to the page below and type on the home row keys to play a blues riff (type multiple keys at the same time etc.)
http://davealger.com/jthump/
The way this works is to create invisible <iframe> components that play a sound before destroying the frame.
I know it is a total hack and I look forward to better HTML 5 multi-channel audio support in the future.

Is there a reliable way to time javascript animations with an audio file playing in the browser?

For example, I want the page to play an audio file while at the same time have some bullets slide into view at just the right moment that said bullet is talked about in the audio file. A similar effect would also be used for closed captioning. When I say reliable I mean specifically that the timing will be consistent across many common platforms (browser/OS/CPU/etc) as well as consistent in different sessions on the same platform (they hit refresh, it works again just as it did before, etc).
NOTE: It's OK if the answer is 'NO', but please include at least a little quip about why that is.

Check out this animation, which synchronizes a 3D SVG effect to an audio file.
The technique is explained in a blog post at http://mrdoob.com/blog/page/3. Look for the one entitled "svg tag+audio tag = 3D waveform". The key is to create a table of volume values corresponding to the audio file.
You'll obviously have some work to do in studying this example and the Javascript it uses to adapt it to your scenario. And it will probably only work in browsers that support HTML5.

Given the current situation and HTML5 support, I would solve this using Flash.