OK. If one uses the System Sounds Services for iPhone sound effects, there is no way to alter the level of the resulting sounds programmatically. Even worse, if one reduces the volume using the ringer volume control on the side of the iPhone to a very low level, then starts the app, the sound effects will be inaudible. On the other hand, if one increases the hardware level to the max before starting the app, sound effects will be uncomfortably loud. To all intents and purposes, this renders the System Sounds APIs useless (or at least ill-advised.) All of this is moot with regard to the iPod, as it does not show this behavior (after all, it isn't a phone.)
I decided to use an AVAudioplayer to play sound effects. Under iPhone SDK 3.1, my existing aiff files (mostly u-law format) work fine, but they won't play under SDK 3.0, and I get an error msg that the codec can't be found. According to Apple's documentation, I can use any supported file format under the caf umbrella, but there must be a codec available.
I have searched diligently, but although I have found lists of codecs available for Mac OS X, I can't find a list of codecs for the iPhone, particularly for SDK 3.0. Can anyone point me to such a list? I want my game (Imp or Oaf?) to work on OS 3.0 and later. I can use mp3 files, but there are latency problems there.
Thanks,
Dan
I can't point you to a list, but ima4 has worked for me since day 1. ima4 has a 1/4 compression ratio.
In Terminal, do this:
afconvert -f caff -d ima4 original_filename.wav
Related
We are working on a prototyp application using unity3d. Your goal is to create a fluid and fun to use cross platform app.
The problem we facing right now is streaming (h.264 - mp4) video content over the web. This will be a major feature of our app.
I have already tried MovieTextures and the www class but it seems the files must be in ogg format which we can not provide. On the other hand handheld.playfullscreenmovie seems to be an android and ios only feature which uses the build in video player. This would be great if it would be supported on other platforms (e.g. Win8-Phone) as well.
Is there another cross platform option to stream (h.264 - mp4) video content over the web and display in full screen or as gui object? Or are there any plans to support something like this in the near future? Or is there a stable plugin for such a task?
Thanks
As of Unity 5 Handheld.PlayFullScreenMovie supports Windows Phone and Windows Store as per http://docs.unity3d.com/ScriptReference/Handheld.PlayFullScreenMovie.html
On Windows Phone 8, Handheld.PlayFullScreenMovie internally uses Microsoft Media Foundation for movie playback. On this platform, calling Handheld.PlayFullScreenMovie with full or minimal control mode is not supported.
On Windows Store Apps and Windows Phone 8.1, Handheld.PlayFullScreenMovie internally uses XAML MediaElement control.
On Windows Phone and Windows Store Apps, there generally isn't movie resolution or bitrate limit, however, higher resolution or bitrate movies will consume more memory for decoding. Weaker devices will also start skipping frames much sooner at extremely high resolutions. For example, Nokia Lumia 620 can only play videos smoothly up to 1920x1080. For these platforms, you can find list of supported formats here: Supported audio and video formats on Windows Store
mp4 is not a streamable container. If you read the ISO specification, you will see that MP4 can not be streamed. This is because the MOOV atom can not be written until all frames are know and accounted for. This 100% incompatible for live video. There are supersets of MP4 used in DASH that make this possible. Essentially, they create a little mp4 (called a fragment) file every couple seconds. Alternatively you can use a container designed for streaming such as FLV or TS.
You will probably need to step outside the unity sdk a bit to enable this.
I want to do some DSP effect processing, create effect like flanger, echo, etc.
Could it be done via OpenAL? Or should I use enterely different framework/library?
Since iOS 5.0 some of the DSP effects are natively supported by OpenAL.
For example, reverb is supported with emulation for more than 10 different spaces (Small/Medium/Large Room, Medium/Large Hall, Plate, Medium/Large Chamber, Cathedral and several variations).
You can find a good reference implementation in the ObjectAL wrapper. The repository is available at https://github.com/kstenerud/ObjectAL-for-iPhone
Grab the source from this repository, load "ObjectAL.xcodeproj" and run the ObjectALDemo target on any iOS 5.0 device (should also work on the simulator). This will give you a good starting point and feeling of what the reverb effect is capable of. I personally recommend taking advantage of the ObjectAL library instead of working with OpenAL directly.
Good luck with your project!
Just write your own audio library. iOS devices don't have hardware acceleration for OpenAL. It isnt particularly difficult to do, and then you can also use apples audio units (some of which are hardware accelerated).
What kind of audio files are you using in your iPhone games/apps?
I have a game with 30MB of sounds in .wav format and I'm thinking of maybe converting to .mp3 to reduce the app size... Is there a major difference in performance? Any other issues?
Keep in mind that certain codecs run in hardware and others in software. Therefore not all compressions will allow for simultaneous playback of more than one sound. For example, if you have a sound playing, a UI sound like a beep may not play if both were trying to use the same codec. For more info, see:
http://developer.apple.com/iphone/library/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/AudioandVideoTechnologies/AudioandVideoTechnologies.html#//apple_ref/doc/uid/TP40007072-CH19-SW6
iPhone Audio Hardware Codecs
iPhone OS applications can use a wide range of audio data formats. Starting in iPhone OS 3.0, most of these formats can use software-based encoding and decoding. You can simultaneously play multiple sounds in all formats, although for performance reasons you should consider which format is best in a given scenario. Hardware decoding generally entails less of a performance impact than software decoding.
The following iPhone OS audio formats can employ hardware decoding for playback:
AAC
ALAC (Apple Lossless)
MP3
The device can play only a single instance of one of these formats at a time through hardware. For example, if you are playing a stereo MP3 sound, a second simultaneous MP3 sound will use software decoding. Similarly, you cannot simultaneously play an AAC and an ALAC sound using hardware. If the iPod application is playing an AAC sound in the background, your application plays AAC, ALAC, and MP3 audio using software decoding.
To play multiple sounds with best performance, or to efficiently play sounds while the iPod is playing in the background, use linear PCM (uncompressed) or IMA4 (compressed) audio.
To learn how to check which hardware and software codecs are available on a device, read the discussion for the kAudioFormatProperty_HardwareCodecCapabilities constant in Audio Format Services Reference.
Both AAC and CAF formats work fine and offer decent file sizes. For certain background looping tracks I found MP3 files getting too big, but YMMV. Experimenting with a decent sound editing app is the only way to find the right balance between size and quality. I've had pretty good luck with Audacity and Amadeus Pro.
Suggest listening to the output with a pair of really good noise-isolating headphones on the device itself. Most people won't be listening to your stuff with these but as you decrease sound quality to shrink file sizes you'll start getting static and hum artifacts. It's just a matter of balancing size vs. quality and what you're willing to live with.
I use a combination of WAV files (for sound effects) and MP3 (for music), which seems to work fine. You can have trouble if you try to play multiple MP3 files at the same time - drop outs, or performance degradation, depending on your AudioSession settings.
If I had to compress my sound effects, I'm not sure which codec has the least decoding overhead. Something like Apple Lossless would likely work well, and would cut the size roughly in half.
I find mp3 fine, but keep in mind that decoding on the iPhone/Touch2G is only about 2.5x realtime speed.
I'm having a hard time trying to record something other than linear PCM on the iPhone :-(
The samples I've found (SDK's SpeakHere, Zdziarski's and Sadun's books and the one at trailsinthesand.com) all use linear PCM but I'd like a commonly used compressed format instead (no ima4 or whatever the name is...).
I just cannot figure out how to tweak the sample code to be used with, for example AAC, MP3 or AMR instead. Any suggestions and hints for how to do that are much appreciated!
(Btw, I do not think an MP3-encoder nor AMR-encoder are available due to licensing issues, but AAC does exist, or???)
Edit/Update: I stumbled upon the following text in Apple's "iPhone Application Programming Guide", 2009-01-06, page 137, section: Recording Audio:
"You can record audio in any of the formats listed in “Preferred Audio Formats in iPhone OS” (page 140)", and as preferred audio formats on page 140 are: "For compressed audio when playing one sound at a time, and when you don’t need to play audio simultaneously with the iPod application, use the AAC format packaged in a CAF or m4a file."
Thus, I interpret that as a clear indication that it is indeed, not only possible, but even preferable, to record audio in AAC format wrapped up in a m4a file, which is just what I want. But still, I am not able to achieve that?!
Thanks,
/John
Keep looking at those docs. In "Core Audio Essentials", the section "Core Audio Plug-ins: Audio Units and Codecs" notes that:
iPhone OS contains the recording
codecs listed in Table 2-5. As you can
see, neither MP3 nor AAC recording is
available. This is due to the high CPU
overhead, and consequent battery
drain, of these formats.
Table 2-5 lists several formats, but as the text notes does not include the ones you're looking for. If you want those formats you'll have to bring your own encoder.
It is possible in iPhone 3GS and iPod 2nd generation and above. They have a hardware enconder for AAC.
There is an Apple example project for this that does exactly what you want to do:
iPhoneExtAudioFileConvertTest
A tip for using faac to convert from iPhone-output linear pcm files to aac format:
I found by experimentation that you have to use the -X flag on the command-line version of faac (running on Mac OS X), which "swaps the input bytes." (I guess it changes the endian-ness.)
So, for example, if you audio recorded the file linear.pcm on your iPhone, you could then run:
faac -XP linear.pcm
on your mac to convert that into the aac file linear.aac.
I'm guessing this means you might be able to use faac within your app to do the conversion, if you wanted to, since it's a C library.
Also note that, technically, the files output by iPhone's audio services are usually CAF files, Core Audio Format, which is sort of a wrapper format around a bunch of possible encodings: Apple's docs on CAF. The above command line works fine for me even though linear.pcm starts with the caff header.
Have you tried Lame mp3 encoder? Or faac/faad AAC codecs? You can embed them in ffmpeg for even more audio codecs.
Why don't try TPAACAudioConverter written by the legendary Michael Tyson ?
TPAACAudioConverter is a simple Objective-C class that performs the
conversion of any audio file to an AAC-encoded m4a, asynchronously
with a delegate, or converts any audio provided by a data source class
(which provides for recording straight to AAC).
Can iphone mix two sound files or build custom equalizer?
I have studied for weeks about this problem,
and it seems unable to use iphone-sdk to mix two or more sound files or to build custom equalizer.
Is anyone have the experience to do this?
Yes you can. AVAudioPlayer can play multiple sounds and you can control the volume for each. Or you can use Audio Units and have more control over the audio data.
aurioTouch is a good sample app for what you are thinking of.
For simple playback of sound files you can use the AVAudioPlayer class introduced in the 2.2 SDK. It provides playback and volume controls for playing any audio file. As far as I am aware, there are no restrictions on the number of sound files you can play on the iPhone. The only restriction on playing sound files is that you may only play one AAC or MP3 compressed file at a time, the rest of the files must be either uncompressed or in the IMA4 format.
If your needs are more low-level (If you need to do DSP) you might want to look at AudioQueue Services or AudioUnits - two Mac OS X audio processing APIs that are also available on the iPhone.