I am using AVAudioRecorder for recording audio in .caf format. When the user will resume this recording the new recording must append with the old recording. So how can i combine two .caf audio files.
You can do it using ExtAudioFileService. In ios developer library they had provided two examples to convert one audio file to another format. In these they are opening one audio file for reading and another file for writing (converted audio). You can change or updated code to read from two files and write them to one out put file in same format(caf) or compressed format. First you have open first audio file and read every packets from it and write it to a new audio file. After finishing first audio file, close the file and open second audio file for reading. Now read every packets from second audio file and write to newly created audio file and close second audio file and new audio file.
Please find the links(1,2) for these sample codes ....
Hope this helps you...and good luck. :)
Related
I want to merge two recorded audio files (.caf)in an iphone .is there any solution?for recording am using avaudioplayer.
answered By: MidHere
You can do it using ExtAudioFileService. In ios developer library they had provided two examples to convert one audio file to another format. In these they are opening one audio file for reading and another file for writing (converted audio). You can change or updated code to read from two files and write them to one out put file in same format(caf) or compressed format. First you have open first audio file and read every packets from it and write it to a new audio file. After finishing first audio file, close the file and open second audio file for reading. Now read every packets from second audio file and write to newly created audio file and close second audio file and new audio file.
Please find the links(1,2) for these sample codes .... Hope this helps you...and good luck. :)
I am working on audio recording. I am able to record my audio in caf (Core audio format). Now I want to record sound in .mp3 or .amr.
I tried a lot of google but didn't found anything. I am not sure if my steps following work:
Write that Audio with .caf extention to document dir
Read data from that file
write the file again with .mp3 or .amr extention
I have 100% doubt that this will not going to work as this will just re save file with some other extension. This won't change audio codec.
I thought that for converting any format whether it is audio or video we need to change its codecs and data sequence.
Please also suggest me any player which don't play .caf files not anything else. So I can make sure that my files are converted successfully.
UPDATE Please also let me know that the way I am re-writing data with different extension is correct in the way I am needed?
You might be interested in the iPhoneExtAudioFileConvertTest example.
The MP3 format is however not available due to patents, maybe you can use LAME.
From the Document The Basics: Audio Codecs, Supported Audio Formats, and Audio Sessions
Hi all
I have multi mp3 files, each file have difference sound. Now i need overlap all of them to one file to have a mp3 file with all other sound. Can i do that with ffmpeg or other tool?
Thank for your help.
IMO, can't be done with ffmpeg.
I would decode all mp3 to .wav files and use Audacity to mix all sources to a single stereo .wav. Then, you can easily reencode this to mp3.
Audacity
I am working on a project that requires me to send raw headerless ulaw or linear pcm data to a server.
I am using the AVAudioRecorder and I can save out audio files to the phone quite easily, but the problem is that it no matter what I try and do, they get wrapped in a caf file or stamped with some kind of header.
It's my understanding that a caf file is just a wrapper file for raw audio data and that this audio data can be in various formats including linear pcm and ulaw.
So my questions are, how can I generate a raw audio file without the caf wrapper to begin with (ie just the headerless raw audio stuffed into a file) or if I record a caf that contains the raw Ulaw or linear pcm audio data, how can I easily go in and extract just the raw audio data from the caf file and leave everything else behind.
If the audio data in the CAF is already in the format you need it in, I'd use the AudioFile API to grab the caf file's audio data and write them to a headerless/RAW file before uploading to my server.
If you need to convert the CAF's data, use the ExtAudioFile API instead. Either way, pretty straightforward.
http://developer.apple.com/library/ios/#documentation/MusicAudio/Reference/AudioFileConvertRef/Reference/reference.html
http://developer.apple.com/library/ios/#documentation/MusicAudio/Reference/ExtendedAudioFileServicesReference/Reference/reference.html
If you use the Audio Queue API for recording, instead of AVAudioRecorder, you will have access to raw PCM sample buffers, and can write those out to a flat file for later sending to your server.
I am making an iPhone recording app that needs to submit the sound file as a .wav to an external server.
Starting from the SpeakHere example, I am able to record sound as a file, but only as .caf
Does anyone know how to record it as a wav instead? Or how to convert from .caf to .wav on the iphone? (The conversion must happen on the phone)
EDIT:
I'm wondering if anything can be done with using kAudioFileWAVEType instead of kAudioFileCAFType in AudioFileCreateWithURL
Yup, the key is kAudioFileWAVEType
AudioFileCreateWithURL (
audioFileURL,
kAudioFileWAVEType,
&audioFormat,
kAudioFileFlags_EraseFile,
&audioFileID
);
Changing to WAVE from CAF in the SpeakHere example causes the recording to be as wav. I also edit the same thing in the playback class, and changed the filename to be Recording.wav
Have a look at libsndfile. It is a well used (including by Audacity) C library for working with lots of file formats. It supports read and write of a variety of CAF and WAV formats.
The CAF File structure and WAV format are fairly similar. If the worst comes to the worst, converting shouldn't be too hard.
It would involve taking the Audio data chunk, and copying as is into the WAV file, and using the information in the Audio Description Chunk to add an equivalent fmt subchunk for the WAV file. It is fairly simple byte copying.
However, be aware (as Eric pointed out) there are licensing issues, see: Can the Libsndfile library be used on the iPhone iOS?