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I'm trying to

  1. record voice from an Android device,
  2. have the data encoded as some audio encoding (M4A, FLAC, Ogg)
  3. stream upload it to my server (chunked http post) - while the recording is ongoing.

Any ideas how to achieve these ?

I tried to do use Android's MediaRecorder (which records audio, encodes it and saves to File) and to use Android's HttpClient with InputStreamEntity which allows uploading data from an input stream. I used "StreamingLoop" from https://github.com/Teaonly/android-eye/blob/master/src/teaonly/droideye/StreamingLoop.java to connect the output file descriptor to the inputStream so I could use the MediaRecorder's output for the HttpClient's input.

However this failed - When I stop the recording I get:

06-27 17:58:47.259: A/libc(6759): Fatal signal 11 (SIGSEGV) at 0x00000010 (code=1), thread 6759

which crashes the application, and the file that arrives to the server is unplayable by VLC, so this is twice a failure.

Any ideas for a different method to do requirements 1..3 above or how to debug it?

Iftah
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3 Answers3

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You could use MediaRecorder for that. The setOutputFile function from MediaRecorder can take a file descriptor. Luckily Android allows you to get a file descriptor from a Socket. Read this post for code and details.

As the afore-linked post mentions, you will have control over the stream, which means you can store it in a buffer and perhaps pass it to a ChunkedOutputStream. This even allows you to stream audio on the fly as you are recording if you'd want.

If you use LocalSocket instead of Socket, you can get the fileDescriptor directly by calling getFileDescriptor on the LocalSocket instance.

Community
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  • sorry I was away and unavailable for feedback. Thanks, you gave me some ideas, I'll try it tomorrow and let you know. – Iftah Jul 05 '13 at 20:31
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use Audiorecord class and not mediaRecorder. API for the former gives you direct access to the buffer backing the microphone. You have control over a handler that writes from the buffer to a stream ( as in http chunked-encoding connection ). That will handle your streaming requirement.

Look at a git proj using audioRecord...

https://github.com/Audioboo/audioboo-android?source=c

see class=FLACRecorder.run() where it reads the AudioRecord buffer and writes it to the encoder(FLAC). If you want to stream the flac-encoded bytes, you can use this app , get the bytes downstream of the encoder and write that to the http connection like in this class.

Robert Rowntree
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  • I think some of my problems relate to AAC encoding broken for streaming on my device (like for the question http://stackoverflow.com/questions/16124198/android-mediarecorder-is-not-generating-a-streamable-aac-lc-audio-using-audioenc?rq=1 ) which I mistook for failure to stream correctly. This AudioRecord approach and the FLAC encoder look promising. – Iftah Jul 06 '13 at 21:52
  • the link is not valid can you add the new github link – YLS Feb 02 '21 at 19:38
  • https://github.com/hannesa2/audioboo/blob/master/app/src/main/java/fm/audioboo/application/FLACRecorder.java upd on the link – Robert Rowntree Feb 02 '21 at 20:36
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When looking on the StreamingLoop I am confused: are you uploading the stream with StreamingLoop or with HttpClient?

If you really do it with HttpClient you can easily connect the two streams with java.io.PipedReader and java.io.PipedWriter.

Than you config your MediaRecorder to write to the PipedWriter and your HttpClient to read from your PipedReader. Both must run on different threads.

ChrLipp
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  • sorry I was away and unavailable for feedback - my problem which I tried to overcome with the StreamingLoop is is that the MediaRecorder does not output a stream but writes to a file descriptor instead. The streaming loop allows me to translates the File descriptor into a stream (since I can get the file descriptor of a local socket) which I plug into the HttpClient for upload – Iftah Jul 05 '13 at 20:28