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Decoder input mp3 info #31

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Decoder input mp3 info #31

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3 changes: 2 additions & 1 deletion examples/mp32wav.js
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Original file line number Diff line number Diff line change
Expand Up @@ -47,7 +47,8 @@ decoder.on('format', onFormat);
input.pipe(decoder);

function onFormat (format) {
console.error('MP3 format: %j', format);
console.error('MP3 info: %j', decoder.info());
console.error('output format: %j', format);

// write the decoded MP3 data into a WAV file
var writer = new wav.Writer(format);
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10 changes: 10 additions & 0 deletions lib/decoder.js
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Expand Up @@ -153,3 +153,13 @@ Decoder.prototype._transform = function (chunk, encoding, done) {
read();
}
};

/**
* Calls `mpg123_info()` to get info about the input mp3 format.
*/

Decoder.prototype.info = function () {
var info = binding.mpg123_info(this.mh);
debug('info: %j', info);
return info;
};
25 changes: 25 additions & 0 deletions src/node_mpg123.cc
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Expand Up @@ -139,6 +139,30 @@ Handle<Value> node_mpg123_getformat (const Arguments& args) {
return scope.Close(rtn);
}

Handle<Value> node_mpg123_info (const Arguments& args) {
UNWRAP_MH;
mpg123_frameinfo info;
int ret;
Local<Value> rtn;
ret = mpg123_info(mh, &info);
if (ret == MPG123_OK) {
Local<Object> o = Object::New();
o->Set(String::NewSymbol("version"), Number::New(info.version));
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version, vbr and modeExtension match standard mp3 header values, there are no constants exposes at node-lame for these, but I can add them if necessary.

o->Set(String::NewSymbol("layer"), Number::New(info.layer));
o->Set(String::NewSymbol("bitRate"), Number::New(info.bitrate));
o->Set(String::NewSymbol("sampleRate"), Number::New(info.rate));
o->Set(String::NewSymbol("mode"), Number::New(info.mode));
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this one will match lame.MONO|STEREO|etc.

o->Set(String::NewSymbol("modeExtension"), Number::New(info.mode_ext));
o->Set(String::NewSymbol("frameSize"), Number::New(info.framesize));
o->Set(String::NewSymbol("emphasis"), Number::New(info.emphasis));
o->Set(String::NewSymbol("vbr"), Number::New(info.vbr));
o->Set(String::NewSymbol("averageBitRate"), Number::New(info.abr_rate));
rtn = o;
} else {
rtn = Integer::New(ret);
}
return scope.Close(rtn);
}

Handle<Value> node_mpg123_safe_buffer (const Arguments& args) {
HandleScope scope;
Expand Down Expand Up @@ -502,6 +526,7 @@ void InitMPG123(Handle<Object> target) {
NODE_SET_METHOD(target, "mpg123_current_decoder", node_mpg123_current_decoder);
NODE_SET_METHOD(target, "mpg123_supported_decoders", node_mpg123_supported_decoders);
NODE_SET_METHOD(target, "mpg123_getformat", node_mpg123_getformat);
NODE_SET_METHOD(target, "mpg123_info", node_mpg123_info);
NODE_SET_METHOD(target, "mpg123_safe_buffer", node_mpg123_safe_buffer);
NODE_SET_METHOD(target, "mpg123_outblock", node_mpg123_outblock);
NODE_SET_METHOD(target, "mpg123_framepos", node_mpg123_framepos);
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