Creating a WAV file from raw PCM data using the Android SDK

Question

I'm trying to use the AudioRecord class to record a WAV file. The problem is that it only supplies the raw PCM data, and if I write it to a file, there is no header information, so it will not play in any media player. How can I create a WAV file from this raw data?

Or alternatively, is there any other way to record sound in Android to a WAV file (or, alternatively MP3)?

Oh, and I know that MediaRecorder can'y be used because it doesn't support either WAV or MP3 formats.

Solution

OK, I've got this figured out. This post was crucial in helping me: http://computermusicblog.com/blog/2008/08/29/reading-and-writing-wav-files-in-java

Basically, I used ByteArrayOutputStream to write the raw PCM data from AudioRecord, which then lets me get the byte array and its size when the process is done. I can then use that data in conjunction with the SampleRate, BitRate, and Stereo/Mono settings to create the WAV header as per the link above. The resulting file works perfectly!

Comments

[user496854]

I definitely need the output file to be either a WAV (PCM encoded), or an MP3. The service where it's being uploaded to requires this. So, as far as I can see, I can't use MediaRecorder. I'm also

[user496854]

I definitely need the output file to be either a WAV (PCM encoded), or an MP3. The service where it's being uploaded to requires this. So, as far as I can see, I can't use MediaRecorder. I'm also quite bad at all the low-level stuff, so I don't know how good I'd be at creating the heade myself. Aren't there java packages that have this capability?

[user496854]

I actually found this: computermusicblog.com/blog/2008/08/29/… , which made it a lot easier to get this working. But I'm not sure how to get the size of the datat chunk for byte 40. I wrote the raw PCM data to a file, so would it just be the size of that file?

[user496854]

Why? it has no support for WAV or MP3 output

[Shrikanth Kalluraya]

can you show a sample code how you achieved this. I have a similar requirement

[Scorpion]

Can you give me some idea about how you have used wavIo file in your code? There are main 2 methods, read and save. I am recording audio in android using AudioRecord class. And i am writing data byte by byte.. Can you please help as my audio is not getting recorded properly.

[topher217]

Link is broken. Do you still have access to this code or some example illustrating the solution?