We are a developing an application which is supposed to play long audio files. duration of audio file can be upto 23 hours...
we are trying to use this AVAuidoPlayer for this purpose. To perform fast forward we are setting CurrentTime property of AVAudioPlayer. if the forward duration is just few minutes or even upto 20 minutes everything works fine. But if we try to jump by say 2 hours time then setCurrentTime call on the player take too long time ( almost 30-40 seconds). This is not acceptable behavior.
please let me know if anybody managed to successfully use AVAudioPlayer setCurrentTime property to jump long durations (say 2 hours)
What is the file format of your file?
I had this problem with MP3, it worked better with AAC.
Related
I have large looping background music files of up to 10 minutes length. The sounds are looped perfectly and if the player introduces no delay you would not notice where the loop point is.
Can AVAudioPlayer play them without that the user will hear a gap caused by latency or other problems with looping?
You might be hearing a delay because your music is compressed (mp3 for example). AVAudioPlayer has to decode the mp3 as it streams. If you had the same music in an uncompressed format, it would take significantly more disk space, but would loop seamlessly.
As long as you don't stop/start it at the end and you set numberOfLoops to a negative integer, it should work.
I had problems trying to create seamless loops. I tried using the numberOfLoops property, with no success. I tried switching to uncompressed audio files, with no success. I even tried switching to an AVAudioQueuePlayer, queued with multiple instances of the same asset, with no success. In the end I solved the problem by creating two instances of AVAudioPlayer (player1 & player2) and switching between them. I began playback of player1 and used player2's prepareToPlay method, and the play(atTime time:) method setting the TimeInterval to player1.deviceCurrentTime - player1.currentTime + player1.duration.
I then used the delegate method audioPlayerDidFinishPlaying to prepare player1 to restart playback after player2 was done. To be honest, I don't know why this approach worked and simply setting numberOfLoops to -1 did not. But it may work for you also
I am developing an application in that I want to play two video at the same time, That is not possible using MPMoviePlayer. So I have used AVQueuePlayer To play video. As I am success to play video but the problem is in jumping to particular time. For that we have method call seekToTime and we need to variable of the CMTime datatype.
I am able to jump at time in 1,2,3 seconds etc, My problem that I want to jump at Time 1.2, 1.3 , 1.4 second etc. but I am not able to move the video at that time.
Can any one know the solution of this problem than please help me to solve the problem.
The seekToTime: method, however, is tuned for performance rather than precision. If you need to move the playhead precisely, instead you use seekToTime:toleranceBefore:toleranceAfter Reference
toleranceBefore: The accuracy of the time before to which you would like to move the playback cursor.
[time-beforeTolerance]
toleranceAfter: The accuracy of the time after to which you would like to move the playback cursor.
[time+afterTolerance]
Lets say both parameters represents the margin of in-accuracy.
I have seen other Question on SO using self.player.currentItem.asset.duration to get the duration.
Good Luck.
Hi I have a locally stored 5:00 minutes mp3 files in my iPhone app.
I would like to know if it is possible to play just an interval from that file using AVAudioPlayer after it is readyToPlay, lets say from 0:25 to 1:34.
If it is possible how can I achieve that?
I know I can move the playhead cursor using setCurrentTime: but how do I let the AVAudioPlayer know how many seconds it should play from that currentTime.
Any help is highly appreciated.
You will need to set a timer which will stop that playing after particular time interval.
#Horatiu you can use NSTimer to schedule it for a particular time interval after you have use setCurrentTime: method, and in the selector method of the NSTimer you can make the audioPlayer stop.
Fire a timer when you start playing the file. When the required time is reached pause or stop the player
I'm working on creating a simple metronome on the iPhone. What the app does right now is to run a timer, entering the timer's function every 1/1000th of second. Then it checks the current time vs time of starting the app (I'm using CACurrentMediaTime() function).
CFTimeInterval currentTime = CACurrentMediaTime();
if (self.beatingStartTime == 0) {
self.beatingStartTime = currentTime;
}
if ( (currentTime - self.beatingStartTime) >= self.timeIntevalBetweenTicks * self.internalTimerCounter ) {
self.internalTimerCounter ++;
// ...
}
If there is a good moment to play audio, the code using OpenAL to play it gets fired.
Basicly that's it. I checked the sounds played when running both in simulator as well as on 2 devices (iPad and jailbroken iPhone 3GS) and there is a problem - when I recorded the sound and reviewed the waveform in Reaper software, some sounds play a bit too late, and some of them - bit too early (even I could understand the "too late" part, I don't really get how it can play earlier then it should - since the app checks the number of seconds every time, it basicly can't be ealier then specified time - yet it is, according to my recods).
At the same time there are some metronome apps that are known for being "rock-solid" when it comes to timing, so I guess there is a way. I just wonder what I'm missing...
edit: Changing timer call from 1/1000th second to, for example 1/100th doesn't help.
edit 2: When I switched from timer to threads (and I put the thread to sleep for specified time) I still get a strange behavior. The tempo moves around and while I could understand a little lag and playing some sounds too late, the problem is some of them do play too early - it means time distance between 2 beats is less then the time that should pass.
The diffrence is about 3%, which translates to about 10-15 miliseconds, which is quite a lot for me. Anyone got an idea why the sound can play earlier? I tried it both on iPhone simulator and on iPad actual device, and my only guess is there's something wrong with the timer - CACurrentMediaTime() returning more seconds that it should. Is it even possible?
Try using an NSSound, and load it up as an instance variable and don't release it unless your metronome isn't running. Delays can be caused by loading the file into memory on the loop. The other thing to consider is that a metronome probably doesn't need to poll every 1/1000th of a second. If you do it less often, you're less likely to saturate the CPU and you might get more consistent results.
Lastly, check out how Apple's demo works: http://developer.apple.com/library/ios/#samplecode/Metronome/Introduction/Intro.html
Might give you a better idea how to accomplish what you're trying to do :)
What you want is COCOS DENSHION which is a simple reliable easy to use sound library, that we have found solves all problems.
I (just personally) don't like "Cocos2D" but you can just take and use CocosDenshion.
Secondly -- 1000th of a second is ridiculous for a timer. Just totally forget it.
Thirdly -- AVAudioPlayer is worthless as you found.
Note - "ObjectAL" is a new, perhaps better, alternative
to CocosDenshion. Check it out.
I'm making an iPhone game application using Core Audio, Extended Audio File Services.
It works OK, but when I first call AudioOutputUnitStart, it takes about 1-2 seconds.
After the second call, no problem.
For a game application, 1-2 seconds is very noticeable.
(I tested this on iPhone simulator, and iPhone 3GS)
Also, if I leave the game for about 10 seconds, first call of AudioOutputUnitStart after the leave also takes time.
I'm using a 5-second AAC 160kbps file to play.
For a 5-second file, why not convert that file into a linear PCM wav or aif file? It shouldn't be that much bigger, plus you don't have to involve the AAC decoder in the process.