AudioHandler

AudioHandler.cs

// Copyright © 2019 The CefSharp Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

using System;
using System.IO;
using System.Runtime.InteropServices;
using System.Text;
using CefSharp.Enums;

namespace CefSharp.Example.Handlers
{
    public class AudioHandler : IAudioHandler
    {
        private readonly MemoryStream stream = new MemoryStream();
        private ChannelLayout channelLayout;
        private int channelCount;
        private int sampleRate;

        void IAudioHandler.OnAudioStreamPacket(IWebBrowser chromiumWebBrowser, IBrowser browser, int audioStreamId, IntPtr data, int noOfFrames, long pts)
        {
            var channelLayoutSize = 2;
            var sizeOfData = noOfFrames * channelLayoutSize * 4;

            byte[] managedData = new byte[sizeOfData];

            Marshal.Copy(data, managedData, 0, sizeOfData);

            stream.Write(managedData, 0, managedData.Length);
        }

        void IAudioHandler.OnAudioStreamStarted(IWebBrowser chromiumWebBrowser, IBrowser browser, int audioStreamId, int channels, ChannelLayout channelLayout, int sampleRate, int framesPerBuffer)
        {
            this.channelLayout = channelLayout;
            this.channelCount = channels;
            this.sampleRate = sampleRate;
        }

        void IAudioHandler.OnAudioStreamStopped(IWebBrowser chromiumWebBrowser, IBrowser browser, int audioStreamId)
        {
            //WriteWavHeader(memoryStream, false, (ushort)channelCount, 24, sampleRate, sampleRate * channelCount);

            using (var file = File.OpenWrite("test.pcm"))
            {
                //file.Write(byteArray, 0, byteArray.Length);
                stream.WriteTo(file);
            }
        }

        // totalSampleCount needs to be the combined count of samples of all channels. So if the left and right channels contain 1000 samples each, then totalSampleCount should be 2000.
        // isFloatingPoint should only be true if the audio data is in 32-bit floating-point format.
        private void WriteWavHeader(MemoryStream stream, bool isFloatingPoint, ushort channelCount, ushort bitDepth, int sampleRate, int totalSampleCount)
        {
            stream.Position = 0;

            // RIFF header.
            // Chunk ID.
            stream.Write(Encoding.ASCII.GetBytes("RIFF"), 0, 4);

            // Chunk size.
            stream.Write(BitConverter.GetBytes(((bitDepth / 8) * totalSampleCount) + 36), 0, 4);

            // Format.
            stream.Write(Encoding.ASCII.GetBytes("WAVE"), 0, 4);


            // Sub-chunk 1.
            // Sub-chunk 1 ID.
            stream.Write(Encoding.ASCII.GetBytes("fmt "), 0, 4);

            // Sub-chunk 1 size.
            stream.Write(BitConverter.GetBytes(16), 0, 4);

            // Audio format (floating point (3) or PCM (1)). Any other format indicates compression.
            stream.Write(BitConverter.GetBytes((ushort)(isFloatingPoint ? 3 : 1)), 0, 2);

            // Channels.
            stream.Write(BitConverter.GetBytes(channelCount), 0, 2);

            // Sample rate.
            stream.Write(BitConverter.GetBytes(sampleRate), 0, 4);

            // Bytes rate.
            stream.Write(BitConverter.GetBytes(sampleRate * channelCount * (bitDepth / 8)), 0, 4);

            // Block align.
            stream.Write(BitConverter.GetBytes(channelCount * (bitDepth / 8)), 0, 2);

            // Bits per sample.
            stream.Write(BitConverter.GetBytes(bitDepth), 0, 2);


            // Sub-chunk 2.
            // Sub-chunk 2 ID.
            stream.Write(Encoding.ASCII.GetBytes("data"), 0, 4);

            // Sub-chunk 2 size.
            stream.Write(BitConverter.GetBytes((bitDepth / 8) * totalSampleCount), 0, 4);
        }
    }
}