An opencore amr codec JNI wrapper with explanation, And one solution for packaging amr audio files.
中文文档请移步README_CN
- opencore is the multimedia framework of android, which is a originallly contributed by PacketVideo.
- amr is abbreviation for Adaptive Multi-Rate audio codec, which is an audio compression format optimized for speech coding.
- opencore-amr is extracted from opencore as an codec for amr<->pcm encode/decode
- opencore-amr-dndroid is a wrapper for handy usage. You can usage wrapped api in Android Application without any troubles of writing c++ wrapper or ndk mk file.
- amr project offer a solution for packaging amr audio files, in elegant code structure.
-
Add jcenter as your repository in project's build.gradle:
allprojects { repositories { jcenter()//this is the default setting } }
-
Add dependency in your module's build.gradle:
dependencies { compile fileTree(dir: 'libs', include: ['*.jar']) compile 'io.kvh:amr:1.1.1'//this is the lib }
OR: Copy the content if Codec/amr to your module, as follows:
Copy the content if Codec/amr to your project:
Copy content of libs and src to the corresponding folder
- encode
AmrEncoder.init(0);
int mode = AmrEncoder.Mode.MR122.ordinal();
short[] in = new short[160];//short array read from AudioRecorder, length 160
byte[] out = new byte[32];//output amr frame, length 32
int byteEncoded = AmrEncoder.encode(mode, in, out);
AmrEncoder.exit();
- decode
long state = AmrDecoder.init();
byte[] amrframe = new byte[32];//amr frame 32 bytes
short[] pcmframs = new short[160];//pcm frame 160 shorts
AmrDecoder.decode(state, amrframe, pcmframs);
AmrDecoder.exit(state);
- Amr file has 6 bytes of header "23 21 41 4D 52 0A" => "#!amr.", please remember to remove the header before decoding frames, thanks to AAccount's explaination.
record->encode->package amr file->upload(not implemented)
Audio steam is packaged to file in slices, the slice last a few seconds(customizable). This policy is suitable for this scenario: client is under unstable mobile network, client records amr file, sends slice by slice, server re-assembles the slices.
If you are interested in this solution, please refer to Codec/app
- format converter for amr/wav
- test cases
- add docs for framesize
- fix decoding bug of 32bit
- add prebuilds for all archs
- rename package
Please edit the FAQ files to help others, thanks! (赠人玫瑰,手留余香)