MediaCodec dynamically controls the code rate

MediaCodec is an API for encoding and decoding video and audio in the Android operating system. It can handle both hardware codecs (using the device's dedicated hardware) and software codecs (using the CPU for processing). To dynamically control the bitrate of MediaCodec, you can follow the steps below:

1. Create and configure MediaCodec:

First, create a suitable codec instance, configure parameters, and start it. It is very important to choose the right codec and configuration parameters, as this will affect the quality of the output results.

MediaCodec codec = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_VIDEO_AVC);
MediaFormat format = MediaFormat.createVideoFormat(MediaFormat.MIMETYPE_VIDEO_AVC, width, height);
format.setInteger(MediaFormat.KEY_COLOR_FORMAT, colorFormat);
format.setInteger(MediaFormat.KEY_BIT_RATE, initialBitrate);
format.setInteger(MediaFormat.KEY_FRAME_RATE, frameRate);
format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, iFrameInterval);
codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
codec.start();

2. Monitor buffer changes:

Use codec.dequeueOutputBuffer()and codec.dequeueInputBuffer()to listen for changes to the input and output buffers. When processing data, make sure to send it to the codec in the correct order and timestamp.

3. Dynamically adjust bit rate:

To dynamically adjust the bit rate, you need to judge when to adjust based on some conditions, such as network conditions, CPU load, etc. When you decide to adjust the bit rate, you can Bundlecall codec.setParameters()the method with parameters:

int newBitrate = updatedBitrate;
Bundle params = new Bundle();
params.putInt(MediaCodec.PARAMETER_KEY_VIDEO_BITRATE, newBitrate);
codec.setParameters(params);

This will tell the codec to use the new bitrate. Note that not all codecs support changing parameters at runtime, so make sure your device supports this feature.

4. Stop and release the codec:

Make sure to properly stop and release the codec when the codec task is complete or needs to be stopped:

codec.stop();
codec.release();

5. Obtain network status:

To get network status you need to use ConnectivityManagerand NetworkInfoclass.

First, add the following permissions in AndroidManifest.xml:

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

public boolean isNetworkConnected(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivityManager != null) {
        NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
        return activeNetworkInfo != null && activeNetworkInfo.isConnected();
    }
    return false;
}

Call the method where you need to check the status of the network connection isNetworkConnected(). For example:

if (isNetworkConnected(getApplicationContext())) {
    // 设备已连接到网络，执行网络操作
} else {
    // 设备未连接到网络，提示用户或执行其他操作
}

NetworkInfoNote that the class is deprecated as of Android 10 (API level 29) . For API level 24 and higher applications, you can use NetworkCapabilitiesto check the network connection status. Here's an NetworkCapabilitiesexample of use:

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkCapabilities;

public boolean isNetworkConnected(Context context) {
    ConnectivityManager connectivityManager = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
    if (connectivityManager != null) {
        Network activeNetwork = connectivityManager.getActiveNetwork();
        if (activeNetwork != null) {
            NetworkCapabilities networkCapabilities = connectivityManager.getNetworkCapabilities(activeNetwork);
            return networkCapabilities != null && (networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_WIFI) || networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_CELLULAR) || networkCapabilities.hasTransport(NetworkCapabilities.TRANSPORT_ETHERNET));
        }
    }
    return false;
}

This code will check if the device is connected to the network via Wi-Fi, cellular data or Ethernet. As mentioned earlier, methods can be called as needed isNetworkConnected()to check the status of network connections.