济南阿里云代理商：android 网络视频取帧

在Android上获取网络视频的帧可以使用MediaCodec和MediaExtractor类来实现。下面是一个简单的示例代码：

import android.media.MediaCodec;
import android.media.MediaExtractor;
import android.media.MediaFormat;
import android.media.MediaCodec.BufferInfo;
import android.os.Handler;
import android.os.HandlerThread;
import android.util.Log;

import java.io.IOException;
import java.nio.ByteBuffer;

public class NetworkVideoFrameExtractor {
    private static final String TAG = "NetworkVideoFrameExtractor";
    private static final String VIDEO_MIME_TYPE = "video/avc";

    private MediaExtractor mediaExtractor;
    private MediaCodec mediaCodec;
    private HandlerThread handlerThread;
    private Handler handler;

    private boolean isRunning = false;

    public void start(String videoUrl) {
        try {
            mediaExtractor = new MediaExtractor();
            mediaExtractor.setDataSource(videoUrl);

            int trackIndex = selectTrack(mediaExtractor);
            if (trackIndex < 0) {
                Log.e(TAG, "No video track found in " + videoUrl);
                return;
            }

            mediaExtractor.selectTrack(trackIndex);
            MediaFormat format = mediaExtractor.getTrackFormat(trackIndex);

            mediaCodec = MediaCodec.createDecoderByType(VIDEO_MIME_TYPE);
            mediaCodec.configure(format, null, null, 0);
            mediaCodec.start();

            handlerThread = new HandlerThread(TAG);
            handlerThread.start();
            handler = new Handler(handlerThread.getLooper());

            isRunning = true;
            handler.post(new VideoFrameExtractorRunnable());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void stop() {
        isRunning = false;

        try {
            handler.removeCallbacksAndMessages(null);
            handlerThread.quitSafely();
            handlerThread.join();
            handlerThread = null;

            if (mediaCodec != null) {
                mediaCodec.stop();
                mediaCodec.release();
                mediaCodec = null;
            }

            if (mediaExtractor != null) {
                mediaExtractor.release();
                mediaExtractor = null;
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private int selectTrack(MediaExtractor extractor) {
        int numTracks = extractor.getTrackCount();
        for (int i = 0; i < numTracks; i++) {
            MediaFormat format = extractor.getTrackFormat(i);
            String mime = format.getString(MediaFormat.KEY_MIME);
            if (mime.startsWith("video/")) {
                return i;
            }
        }
        return -1;
    }

    private class VideoFrameExtractorRunnable implements Runnable {
        @Override
        public void run() {
            while (isRunning) {
                int inputBufferIndex = mediaCodec.dequeueInputBuffer(10_000);
                if (inputBufferIndex >= 0) {
                    ByteBuffer inputBuffer = mediaCodec.getInputBuffer(inputBufferIndex);

                    int sampleSize = mediaExtractor.readSampleData(inputBuffer, 0);
                    long sampleTime = mediaExtractor.getSampleTime();

                    if (sampleSize >= 0) {
                        mediaCodec.queueInputBuffer(inputBufferIndex, 0, sampleSize, sampleTime, 0);
                        mediaExtractor.advance();
                    } else {
                        mediaCodec.queueInputBuffer(inputBufferIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
                    }
                }

                BufferInfo bufferInfo = new BufferInfo();
                int outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 10_000);
                while (outputBufferIndex >= 0) {
                    mediaCodec.releaseOutputBuffer(outputBufferIndex, true);
                    outputBufferIndex = mediaCodec.dequeueOutputBuffer(bufferInfo, 0);
                }

                if ((bufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
                    break;
                }
            }

            stop();
        }
    }
}

使用示例：

NetworkVideoFrameExtractor videoFrameExtractor = new NetworkVideoFrameExtractor();
videoFrameExtractor.start("http://example.com/video.mp4");

// 循环获取帧数据，可以在UI线程或其他线程中执行
while (true) {
    // 获取视频帧数据并处理
}

videoFrameExtractor.stop();

请记住，在运行此代码之前，需要添加相应的权限（例如INTERNET权限）到AndroidManifest.xml文件中。

在Android上可以使用MediaMetadataRetriever类来从网络视频中获取帧。下面是一个简单的示例代码：

import android.media.MediaMetadataRetriever;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.ImageView;

import androidx.appcompat.app.AppCompatActivity;

import com.bumptech.glide.Glide;

import java.util.HashMap;

public class MainActivity extends AppCompatActivity {

    private ImageView imageView;

    private String videoUrl = "https://example.com/video.mp4";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = findViewById(R.id.imageView);

        // 在后台线程中获取视频帧
        new FrameExtractorTask().execute(videoUrl);
    }

    private class FrameExtractorTask extends AsyncTask<String, Void, String> {

        @Override
        protected String doInBackground(String... urls) {
            String videoUrl = urls[0];

            // 创建MediaMetadataRetriever对象
            MediaMetadataRetriever retriever = new MediaMetadataRetriever();

            try {
                // 设置视频源
                retriever.setDataSource(videoUrl, new HashMap<>());

                // 获取第一帧
                String framePath = getCacheDir().getPath() + "/frame.jpg";
                retriever.getFrameAtTime(0, MediaMetadataRetriever.OPTION_CLOSEST).compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(framePath));

                return framePath;
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                // 释放资源
                retriever.release();
            }

            return null;
        }

        @Override
        protected void onPostExecute(String framePath) {
            super.onPostExecute(framePath);

            // 使用Glide加载图片
            if (framePath != null) {
                Glide.with(MainActivity.this).load(framePath).into(imageView);
            }
        }
    }
}

在上面的代码中，我们使用MediaMetadataRetriever类从网络视频中提取第一帧，并使用Glide库将帧显示在ImageView中。

请注意，这个任务在后台线程中执行，以避免在主线程中执行网络请求和图像处理造成UI卡顿。因此，需要在MainActivity中进行网络权限和Glide库的引用处理等。