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我制作了一个运行良好的收音机应用程序。我也可以播放广播流并获取元数据。流媒体服务来自shoutcast。

唯一的问题是，我将 URL 作为数据源添加到媒体播放器，然后每 5 秒获取一次标题和艺术家。

有什么办法，我可以只发出一个 HTTP 请求，然后拆分音频和元数据，然后将其发送到媒体播放器？

获取元数据的代码。

private void retreiveMetadata() throws IOException {

    int metaDataOffset = 0;

    OkHttpClient client = new OkHttpClient();
    Request request = new Request.Builder()
        .addHeader("Icy-MetaData", "1")
        .addHeader("Connection", "close")
        .addHeader("Accept", "")
        .url(streamUrl)
        .build();

    request.headers("");


    Response response = client.newCall(request).execute();
    InputStream stream = response.body().byteStream();

    //Map<String, List<String>> headers = response..getHeaderFields();

    if (!response.headers("icy-metaint").equals("")) {
        // Headers are sent via HTTP

        String icyMetaInt = response.headers("icy-metaint").toString();
        icyMetaInt = icyMetaInt.replace("[", "");
        icyMetaInt = icyMetaInt.replace("]", "");

        metaDataOffset = Integer.parseInt(icyMetaInt);
    } else {

        // Headers are sent within a stream
        StringBuilder strHeaders = new StringBuilder();
        char c;
        while ((c = (char)stream.read()) != -1) {
            strHeaders.append(c);
            if (strHeaders.length() > 5 && (strHeaders.substring((strHeaders.length() - 4), strHeaders.length()).equals("\r\n\r\n"))) {
                // end of headers
                break;
            }
        }

        // Match headers to get metadata offset within a stream
        Pattern p = Pattern.compile("\\r\\n(icy-metaint):\\s*(.*)\\r\\n");
        Matcher m = p.matcher(strHeaders.toString());

        if (m.find()) {
            metaDataOffset = Integer.parseInt(m.group(2));
        }
    }

    // In case no data was sent
    if (metaDataOffset == 0) {
        isError = true;
        return;
    }

    // Read metadata
    int b;
    int count = 0;
    int metaDataLength = 4080; // 4080 is the max length
    boolean inData = false;
    StringBuilder metaData = new StringBuilder();
    // Stream position should be either at the beginning or right after headers
    while ((b = stream.read()) != -1) {
        count++;

        // Length of the metadata
        if (count == metaDataOffset + 1) {
            metaDataLength = b * 16;
        }

        if (count > metaDataOffset + 1 && count < (metaDataOffset + metaDataLength)) {
            inData = true;
        } else {
            inData = false;
        }

        if (inData) {
            if (b != 0) {
                metaData.append((char)b);
            }
        }

        if (count > (metaDataOffset + metaDataLength)) {
            break;
        }

    }

    // Set the data
    metadata = IcyStreamMeta.parseMetadata(metaData.toString());

    // Close
    stream.close();
}

public static Map<String, String> parseMetadata(String metaString) {
    Map<String, String> metadata = new HashMap();
    String[] metaParts = metaString.split(";");
    Pattern p = Pattern.compile("^([a-zA-Z]+)=\\'([^\\']*)\\'$");
    Matcher m;
    for (int i = 0; i < metaParts.length; i++) {
        m = p.matcher(metaParts[i]);
        if (m.find()) {
            metadata.put((String)m.group(1), (String)m.group(2));
        }
    }

    return metadata;
}

并将 url 传递给媒体播放器的数据源

String url = "http://68.68.109.106:8356/";
mp = new MediaPlayer();
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
try {

    mp.setDataSource(url);
    mp.prepare();

} catch (IllegalArgumentException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
    Toast.makeText(context, e.toString(), Toast.LENGTH_SHORT).show();
} catch (SecurityException e) {
    // TODO Auto-generated catch block
    Log.e(TAG, "SecurityException");
    Toast.makeText(context, e.toString(), Toast.LENGTH_SHORT).show();
} catch (IllegalStateException e) {
    // TODO Auto-generated catch block
    Log.e(TAG, "IllegalStateException");
    Toast.makeText(context, e.toString(), Toast.LENGTH_SHORT).show();
} catch (IOException e) {
    // TODO Auto-generated catch block
    Log.e(TAG, "IOException");
    Toast.makeText(context, e.toString(), Toast.LENGTH_SHORT).show();
}
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1 回答 1

2

The task you try to achieve is not something that is easy to do. (Tho it is not impossible.) The metadata of the stream is only "downloaded" at the start of the stream, so changing it afterwards would have no effect reading the metainformations "cached" from the stream. To read the new properties you have to restart the stream, this will fetch the new headers etc. (But it could cause a break in the stream so it is not really recommended.)

In sound technology it is common to use watermarking. It is a process where you enrich your sound with some kind of data in the not (quality) destructing way. (Usage on YouTube.) Although it is hard to do, there are some ways to hide your information in the stream. I recommend to read this to achieve the goal you want to reach.

Because your hardware is a mobile phone and not all of the Android devices are strong enough you should consider some new HTTP requests. The audio processing is not a cheap thing speaking in terms of CPU, memory etc. There is some other options to consider if you do so. The five second polling is not the best way to get the information, because you could display false information to the user and false information is worse than nothing. I recommend a server side push based on mqtt. Here is a pretty nice example of the usage. A solution based on this method instead of polling is using less traffic and is more accurate.

于 2016-06-16T07:29:42.933 回答