PCM from pipe:1

[belaviyo]

Hi,

I am trying to get PCM data from FFmpeg. I found your node_airtunes does the same thing. I was wondering if you can help me out with this:

I am running FFmpeg by -i audiofile -f f32be -ar 44100 -ac 1 pipe:1. So basically I am trying to print the output of ffmpeg in "PCM 32-bit floating-point" format. Then I used the following code to get the data:

    var blob = new Blob([stdout_data], {type: 'application/octet-binary'});
    var reader = new FileReader();
    reader.addEventListener("loadend", function() {
       console.error(Float32Array(reader.result))
    });
    reader.readAsArrayBuffer(blob);

The output I get by running the code does not make sense. The values are not in [-1, 1] limit. I guess I am doing something wrong during the typed array conversion. Any idea what the problem could be?

[lperrin]

Sorry, I have never played with typed arrays before. Are you sure that FFmpeg outputs the correct data? You could parse your output with node.js and use buffer.readFloatBE() to check that.

[belaviyo]

Thanks. According to my tests the problem was that FileReader could not handle the conversion to typed array.