Recording audio in mp3 format in an iPhone app
Solution 1
You cannot record in MP3, it is a proprietary format when it comes to encoding. These are the settings I use, it comes out to ~150KB for 2 min of recording time:
NSString *tempDir = NSTemporaryDirectory();
NSString *soundFilePath = [tempDir stringByAppendingPathComponent:@"sound.m4a"];
NSURL *soundFileURL = [NSURL fileURLWithPath:soundFilePath];
NSDictionary *recordSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kAudioFormatMPEG4AAC], AVFormatIDKey,
[NSNumber numberWithInt:AVAudioQualityMin], AVEncoderAudioQualityKey,
[NSNumber numberWithInt:16], AVEncoderBitRateKey,
[NSNumber numberWithInt: 1], AVNumberOfChannelsKey,
[NSNumber numberWithFloat:8000.0], AVSampleRateKey,
[NSNumber numberWithInt:8], AVLinearPCMBitDepthKey,
nil];
Also doing conversion is a processor intense operation, if you're sending this audio to a server you can use FFMPEG with the mp3lame library to do audio conversion on the server.
EDIT: this is the code for Android recording, it's set to AMR encoding because AAC is only supported as of Honeycomb.
mediaRecorder = new MediaRecorder();
mediaRecorder.setAudioSource(MediaRecorder.AudioSource.MIC);
mediaRecorder.setOutputFormat(MediaRecorder.OutputFormat.MPEG_4);
mediaRecorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
mediaRecorder.setAudioChannels(1);
mediaRecorder.setOutputFile("sample.m4a");
Solution 2
You cannot record audio in .mp3 file. kAudioFormatMPEGLayer3
is only for playback the .mp3 format audio
. There is no codec available for .mp3 recording
. You need record in aac
or wav
format and convert it into .mp3
format.
Better check out the below link and images:
Here it is a link to learn the basic for converting the audio format:
ios
Updated on June 05, 2022Comments
-
ios almost 2 years
I am developing an iPhone app which records the audio in .wav format.
Here is the code:
NSMutableDictionary* recordSetting = [[NSMutableDictionary alloc]init]; [recordSetting setValue :[NSNumber numberWithInt:kAudioFormatLinearPCM] forKey:AVFormatIDKey]; [recordSetting setValue:[NSNumber numberWithFloat:11025.0] forKey:AVSampleRateKey]; [recordSetting setValue:[NSNumber numberWithInt: 1] forKey:AVNumberOfChannelsKey]; [recordSetting setValue:[NSNumber numberWithInt:16] forKey:AVLinearPCMBitDepthKey]; NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [path objectAtIndex:0]; NSString *myDBnew = [documentsDirectory stringByAppendingPathComponent:@"test.wav"]; recordedTmpFile = [NSURL fileURLWithPath:myDBnew]; NSLog(@"Using File called: %@",recordedTmpFile); recorder = [[ AVAudioRecorder alloc] initWithURL:recordedTmpFile settings:recordSetting error:&error]; [recorder setDelegate:self]; [recorder prepareToRecord]; [recorder record];
Above code is recording audio in .wav format. If I want to record audio in MP3 using key
kAudioFormatMPEGLayer3(mp3)
instead ofkAudioFormatLinearPCM(.wav)
, what other changes do I need to make? Changes in recordSetting dictionary like sample rate, channel and all.Or suggest any audio format which is compatible with both iPhone and Android, smaller in size and can be recorded directly from iPhone app.