我已修改 abalta 提供的代码以实时接受位图（即您不需要将位图保存到光盘）。它还具有性能改进，因为您不需要从磁盘写入然后读取位图。我还增加了原始示例中的 TIMEOUT_USEC，它修复了我遇到的一些与超时相关的错误。
希望这对某人有所帮助。我花了很长时间尝试做到这一点，而不必将大型第三方库打包到我的应用程序（例如 ffmpeg）中，所以我非常感谢 abalta 的回答。
我正在使用 rxjava，因此您需要在应用的 build.gradle 依赖项中使用它：
implementation 'io.reactivex.rxjava2:rxandroid:2.0.2'
如果您尝试写入外部存储，则需要清单中定义的外部存储权限：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
并在系统设置应用中为您的应用手动切换权限，或将权限请求处理添加到您的活动中。
这是课程：
import android.graphics.Bitmap;
import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaCodecList;
import android.media.MediaFormat;
import android.media.MediaMuxer;
import android.util.Log;
import java.io.File;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.CountDownLatch;
import io.reactivex.Completable;
import io.reactivex.android.schedulers.AndroidSchedulers;
import io.reactivex.schedulers.Schedulers;
public class BitmapToVideoEncoder {
private static final String TAG = BitmapToVideoEncoder.class.getSimpleName();
private IBitmapToVideoEncoderCallback mCallback;
private File mOutputFile;
private Queue<Bitmap> mEncodeQueue = new ConcurrentLinkedQueue();
private MediaCodec mediaCodec;
private MediaMuxer mediaMuxer;
private Object mFrameSync = new Object();
private CountDownLatch mNewFrameLatch;
private static final String MIME_TYPE = "video/avc"; // H.264 Advanced Video Coding
private static int mWidth;
private static int mHeight;
private static final int BIT_RATE = 16000000;
private static final int FRAME_RATE = 30; // Frames per second
private static final int I_FRAME_INTERVAL = 1;
private int mGenerateIndex = 0;
private int mTrackIndex;
private boolean mNoMoreFrames = false;
private boolean mAbort = false;
public interface IBitmapToVideoEncoderCallback {
void onEncodingComplete(File outputFile);
}
public BitmapToVideoEncoder(IBitmapToVideoEncoderCallback callback) {
mCallback = callback;
}
public boolean isEncodingStarted() {
return (mediaCodec != null) && (mediaMuxer != null) && !mNoMoreFrames && !mAbort;
}
public int getActiveBitmaps() {
return mEncodeQueue.size();
}
public void startEncoding(int width, int height, File outputFile) {
mWidth = width;
mHeight = height;
mOutputFile = outputFile;
String outputFileString;
try {
outputFileString = outputFile.getCanonicalPath();
} catch (IOException e) {
Log.e(TAG, "Unable to get path for " + outputFile);
return;
}
MediaCodecInfo codecInfo = selectCodec(MIME_TYPE);
if (codecInfo == null) {
Log.e(TAG, "Unable to find an appropriate codec for " + MIME_TYPE);
return;
}
Log.d(TAG, "found codec: " + codecInfo.getName());
int colorFormat;
try {
colorFormat = selectColorFormat(codecInfo, MIME_TYPE);
} catch (Exception e) {
colorFormat = MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar;
}
try {
mediaCodec = MediaCodec.createByCodecName(codecInfo.getName());
} catch (IOException e) {
Log.e(TAG, "Unable to create MediaCodec " + e.getMessage());
return;
}
MediaFormat mediaFormat = MediaFormat.createVideoFormat(MIME_TYPE, mWidth, mHeight);
mediaFormat.setInteger(MediaFormat.KEY_BIT_RATE, BIT_RATE);
mediaFormat.setInteger(MediaFormat.KEY_FRAME_RATE, FRAME_RATE);
mediaFormat.setInteger(MediaFormat.KEY_COLOR_FORMAT, colorFormat);
mediaFormat.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, I_FRAME_INTERVAL);
mediaCodec.configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);
mediaCodec.start();
try {
mediaMuxer = new MediaMuxer(outputFileString, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);
} catch (IOException e) {
Log.e(TAG,"MediaMuxer creation failed. " + e.getMessage());
return;
}
Log.d(TAG, "Initialization complete. Starting encoder...");
Completable.fromAction(() -> encode())
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe();
}
public void stopEncoding() {
if (mediaCodec == null || mediaMuxer == null) {
Log.d(TAG, "Failed to stop encoding since it never started");
return;
}
Log.d(TAG, "Stopping encoding");
mNoMoreFrames = true;
synchronized (mFrameSync) {
if ((mNewFrameLatch != null) && (mNewFrameLatch.getCount() > 0)) {
mNewFrameLatch.countDown();
}
}
}
public void abortEncoding() {
if (mediaCodec == null || mediaMuxer == null) {
Log.d(TAG, "Failed to abort encoding since it never started");
return;
}
Log.d(TAG, "Aborting encoding");
mNoMoreFrames = true;
mAbort = true;
mEncodeQueue = new ConcurrentLinkedQueue(); // Drop all frames
synchronized (mFrameSync) {
if ((mNewFrameLatch != null) && (mNewFrameLatch.getCount() > 0)) {
mNewFrameLatch.countDown();
}
}
}
public void queueFrame(Bitmap bitmap) {
if (mediaCodec == null || mediaMuxer == null) {
Log.d(TAG, "Failed to queue frame. Encoding not started");
return;
}
Log.d(TAG, "Queueing frame");
mEncodeQueue.add(bitmap);
synchronized (mFrameSync) {
if ((mNewFrameLatch != null) && (mNewFrameLatch.getCount() > 0)) {
mNewFrameLatch.countDown();
}
}
}
private void encode() {
Log.d(TAG, "Encoder started");
while(true) {
if (mNoMoreFrames && (mEncodeQueue.size() == 0)) break;
Bitmap bitmap = mEncodeQueue.poll();
if (bitmap == null) {
synchronized (mFrameSync) {
mNewFrameLatch = new CountDownLatch(1);
}
try {
mNewFrameLatch.await();
} catch (InterruptedException e) {}
bitmap = mEncodeQueue.poll();
}
if (bitmap == null) continue;
byte[] byteConvertFrame = getNV21(bitmap.getWidth(), bitmap.getHeight(), bitmap);
long TIMEOUT_USEC = 500000;
int inputBufIndex = mediaCodec.dequeueInputBuffer(TIMEOUT_USEC);
long ptsUsec = computePresentationTime(mGenerateIndex, FRAME_RATE);
if (inputBufIndex >= 0) {
final ByteBuffer inputBuffer = mediaCodec.getInputBuffer(inputBufIndex);
inputBuffer.clear();
inputBuffer.put(byteConvertFrame);
mediaCodec.queueInputBuffer(inputBufIndex, 0, byteConvertFrame.length, ptsUsec, 0);
mGenerateIndex++;
}
MediaCodec.BufferInfo mBufferInfo = new MediaCodec.BufferInfo();
int encoderStatus = mediaCodec.dequeueOutputBuffer(mBufferInfo, TIMEOUT_USEC);
if (encoderStatus == MediaCodec.INFO_TRY_AGAIN_LATER) {
// no output available yet
Log.e(TAG, "No output from encoder available");
} else if (encoderStatus == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
// not expected for an encoder
MediaFormat newFormat = mediaCodec.getOutputFormat();
mTrackIndex = mediaMuxer.addTrack(newFormat);
mediaMuxer.start();
} else if (encoderStatus < 0) {
Log.e(TAG, "unexpected result from encoder.dequeueOutputBuffer: " + encoderStatus);
} else if (mBufferInfo.size != 0) {
ByteBuffer encodedData = mediaCodec.getOutputBuffer(encoderStatus);
if (encodedData == null) {
Log.e(TAG, "encoderOutputBuffer " + encoderStatus + " was null");
} else {
encodedData.position(mBufferInfo.offset);
encodedData.limit(mBufferInfo.offset + mBufferInfo.size);
mediaMuxer.writeSampleData(mTrackIndex, encodedData, mBufferInfo);
mediaCodec.releaseOutputBuffer(encoderStatus, false);
}
}
}
release();
if (mAbort) {
mOutputFile.delete();
} else {
mCallback.onEncodingComplete(mOutputFile);
}
}
private void release() {
if (mediaCodec != null) {
mediaCodec.stop();
mediaCodec.release();
mediaCodec = null;
Log.d(TAG,"RELEASE CODEC");
}
if (mediaMuxer != null) {
mediaMuxer.stop();
mediaMuxer.release();
mediaMuxer = null;
Log.d(TAG,"RELEASE MUXER");
}
}
private static MediaCodecInfo selectCodec(String mimeType) {
int numCodecs = MediaCodecList.getCodecCount();
for (int i = 0; i < numCodecs; i++) {
MediaCodecInfo codecInfo = MediaCodecList.getCodecInfoAt(i);
if (!codecInfo.isEncoder()) {
continue;
}
String[] types = codecInfo.getSupportedTypes();
for (int j = 0; j < types.length; j++) {
if (types[j].equalsIgnoreCase(mimeType)) {
return codecInfo;
}
}
}
return null;
}
private static int selectColorFormat(MediaCodecInfo codecInfo,
String mimeType) {
MediaCodecInfo.CodecCapabilities capabilities = codecInfo
.getCapabilitiesForType(mimeType);
for (int i = 0; i < capabilities.colorFormats.length; i++) {
int colorFormat = capabilities.colorFormats[i];
if (isRecognizedFormat(colorFormat)) {
return colorFormat;
}
}
return 0; // not reached
}
private static boolean isRecognizedFormat(int colorFormat) {
switch (colorFormat) {
// these are the formats we know how to handle for
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420Planar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420PackedSemiPlanar:
case MediaCodecInfo.CodecCapabilities.COLOR_TI_FormatYUV420PackedSemiPlanar:
return true;
default:
return false;
}
}
private byte[] getNV21(int inputWidth, int inputHeight, Bitmap scaled) {
int[] argb = new int[inputWidth * inputHeight];
scaled.getPixels(argb, 0, inputWidth, 0, 0, inputWidth, inputHeight);
byte[] yuv = new byte[inputWidth * inputHeight * 3 / 2];
encodeYUV420SP(yuv, argb, inputWidth, inputHeight);
scaled.recycle();
return yuv;
}
private void encodeYUV420SP(byte[] yuv420sp, int[] argb, int width, int height) {
final int frameSize = width * height;
int yIndex = 0;
int uvIndex = frameSize;
int a, R, G, B, Y, U, V;
int index = 0;
for (int j = 0; j < height; j++) {
for (int i = 0; i < width; i++) {
a = (argb[index] & 0xff000000) >> 24; // a is not used obviously
R = (argb[index] & 0xff0000) >> 16;
G = (argb[index] & 0xff00) >> 8;
B = (argb[index] & 0xff) >> 0;
Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;
yuv420sp[yIndex++] = (byte) ((Y < 0) ? 0 : ((Y > 255) ? 255 : Y));
if (j % 2 == 0 && index % 2 == 0) {
yuv420sp[uvIndex++] = (byte) ((U < 0) ? 0 : ((U > 255) ? 255 : U));
yuv420sp[uvIndex++] = (byte) ((V < 0) ? 0 : ((V > 255) ? 255 : V));
}
index++;
}
}
}
private long computePresentationTime(long frameIndex, int framerate) {
return 132 + frameIndex * 1000000 / framerate;
}
}
用法类似于：
BitmapToVideoEncoder bitmapToVideoEncoder = new BitmapToVideoEncoder(new IBitmapToVideoEncoderCallback() {
@Override
public void onEncodingComplete(File outputFile) {
Toast.makeText(this, "Encoding complete!", Toast.LENGTH_LONG).show();
}
});
bitmapToVideoEncoder.startEncoding(getWidth(), getHeight(), new File("some_path"));
bitmapToVideoEncoder.queueFrame(bitmap1);
bitmapToVideoEncoder.queueFrame(bitmap2);
bitmapToVideoEncoder.queueFrame(bitmap3);
bitmapToVideoEncoder.queueFrame(bitmap4);
bitmapToVideoEncoder.queueFrame(bitmap5);
bitmapToVideoEncoder.stopEncoding();
如果您的录制被中断（前活动正在暂停），您可以中止，它会删除文件（因为无论如何它都会损坏）。或者，只需调用 stopEncoding ，它就会正确关闭文件，以免损坏：
bitmapToVideoEncoder.abortEncoding();
还有一个 getActiveBitmaps() 函数可以查看队列有多大（如果队列变大，您可能会耗尽内存）。这里还有一些代码可以有效地从视图创建位图，以便您可以将其排队（我的应用程序会定期截取屏幕截图并将它们编码成视频）：
View view = some_view;
final Bitmap bitmap = Bitmap.createBitmap(view.getWidth(), view.getHeight(),
Bitmap.Config.ARGB_8888);
// Create a handler thread to offload the processing of the image.
final HandlerThread handlerThread = new HandlerThread("PixelCopier");
handlerThread.start();
PixelCopy.request(view, bitmap, (copyResult) -> {
bitmapToVideoEncoder.queueFrame(bitmap);
}, new Handler(handlerThread.getLooper()));