Question

我在WP7中实现了一个工作音频播放器，它通过HttpWebRequest在线获取音频流，并使用AudioStreamingAgent和MediaStreamSource在后台播放。

获取流的代码如下：

public class AudioTrackStreamer : AudioStreamingAgent 
{
    protected override void OnBeginStreaming(AudioTrack track, AudioStreamer streamer)
    {
        stream = GetDownloadStream(track.Tag);

        // Use sine wave audio generator to simulate a streaming audio feed
        BackgroundMp3MediaStreamSource mss = new BackgroundMp3MediaStreamSource(stream);

        // Event handler for when a track is complete or the user switches tracks
        mss.StreamingCompleted += new EventHandler(mss_StreamingCompleted);

        // Set the source
        streamer.SetSource((MediaStreamSource) mss);
    }
}

我需要更改客户端以获取AES编码流并在播放之前对其进行解码。

我虽然可以创建解码流并将其传递给BackgroundMp3MediaStreamSource。类似的东西：

...
stream = GetDownloadStream(track.Tag);
decodedStream = GetDecodedStream(stream);
BackgroundMp3MediaStreamSource mss = new BackgroundMp3MediaStreamSource(decodedStream);
...


private Stream GetDecodedStream(Stream encoded) {
    Stream destination = new MemoryStream();
    BackgroundWorker streamCopier = new BackgroundWorker();
    streamCopier.DoWork += (o, e) => StreamCopierDoWork(encoded, destination);
    streamCopier.RunWorkerAsync();

    return new NonUiStreamer(destination);
}

private static void StreamCopierDoWork(Stream encoded, Stream destination) {
    const int chunk = 1 * 1024;

    var buffer = new byte[chunk];

    AsyncCallback rc = null;
    rc = readResult => {
        int read = encoded.EndRead(readResult);
        if (read > 0) {
            destination.BeginWrite(buffer, 0, read, writeResult => {
                    destination.EndWrite(writeResult);
                    encoded.BeginRead(buffer, 0, buffer.Length, rc, null);
            }, null);
        }
    };
    encoded.BeginRead(buffer, 0, chunk, rc, null);
}

注意：我还没有解码流。只需将其异步复制到另一个流，看看是否一切正常。

但是当我尝试读取解码流decodedStream.Read(data, 0, 3);的第一个字节时，它返回0个字节。

为什么我不能读取decodeStream？

在wp7中异步复制音频流

0 个答案: