Update recordSampleRate after downsampleBuffer

[expatiating]

In testing this, I used startRecording, stopRecording, and exportWAV similar to below.

audioControl.startRecording(() => {
  audioControl.stopRecording()
  audioControl.exportWAV()
}

When I call exportWAV it appears that sampleRate change done in downsampleBuffer is not reflected in encodeWAV.

The browser records in 44.1 kHz, and downsampling to 16 kHz, and exporting the WAV, the file has 44.1 kHz encoding and the audio played by Audacity was at 44.1 kHz rate. In Audacity I changed the file rate to 16 kHz and the audio plays correctly.

By setting recordSampleRate = exportSampleRate; after downsampling corrected the issue.

[vogler75]

I had the same issue. But I think to change the recordSampleRate is not the best way to fix it. I added an argument sampleRate to the function "encodeWAV" and use this argument instead of the global "recordSampleRate" variable. And where the encodeWAV function is called I passed the exportSampleRate...

function exportBuffer(exportSampleRate) {
        var mergedBuffers = mergeBuffers(recBuffer, recLength);
        var downsampledBuffer = downsampleBuffer(mergedBuffers, exportSampleRate);
        var encodedWav = encodeWAV(downsampledBuffer, **exportSampleRate**);
        var audioBlob = new Blob([encodedWav], { type: 'application/octet-stream' });
        postMessage({
          blob: audioBlob,
          hasContent: encodedWav.hasContent
        });
      }  

function encodeWAV(samples, **sampleRate**) {
        const samplesLength = samples.length;
        let hasContent = false;
        for (let i = 0; i < samplesLength; ++i) {
          if (Math.abs(samples[i]) > 0.05) {
            hasContent = true
            break;
          }
        }

        var buffer = new ArrayBuffer(44 + samples.length * 2);
        var view = new DataView(buffer);

        writeString(view, 0, 'RIFF');
        view.setUint32(4, 32 + samples.length * 2, true);
        writeString(view, 8, 'WAVE');
        writeString(view, 12, 'fmt ');
        view.setUint32(16, 16, true);
        view.setUint16(20, 1, true);
        view.setUint16(22, 1, true);
        view.setUint32(24, **sampleRate**, true);
        view.setUint32(28, **sampleRate** * 2, true);
        view.setUint16(32, 2, true);
        view.setUint16(34, 16, true);
        writeString(view, 36, 'data');
        view.setUint32(40, samples.length * 2, true);
        floatTo16BitPCM(view, 44, samples);

        view.hasContent = hasContent;

        return view;
      }

[expatiating]

@vogler75 you are welcome to add a commit to my PR with your change, your solution adds a bit of additional flexibility. Since we are approaching 2 years on my original fix hopefully your interest gets helps get this PR a review from @palafranchise and this gets fixed.

[vogler75]

@expatiating it seems that I do not have permission to publish a branch on this repo.

[vogler75]

ok, I had to create a fork (was my first time doing a pull request), additionally i create an issue.

[expatiating]

Addresses #22, but see PR #23 for a more complete implementation by @vogler75