我需要创建隐藏了数据的视频。我设法使用mediacodec解码器作为NV21缓冲区提取视频帧并保存，然后使用mediacodec编码器从帧中创建mp4文件。如果正在编码过程中，下面的类负责保存帧文件；如果要从隐蔽视频中提取数据，请检查该值。
public class ExtractMpegFramesBufferDecoder {
private static final String TAG = "ExtractMpegFramesDec";
private static final boolean VERBOSE = true; // lots of logging
// where to find files (note: requires WRITE_EXTERNAL_STORAGE permission)
private File STORE_FRAME_DIRECTORY;
private String INPUT_FILE;
private int frameRate; // stop extracting after this many
private int saveWidth;
private int saveHeight;
private int decodeCount;
private Handler _progressBarHandler;
private int duration;
//
private int MAX_FRAMES;
private boolean fromDecode;
//
public ExtractMpegFramesBufferDecoder(File storeFrameDirectory, String inputVideoPath, int frameRate
, int saveWidth, int saveHeight
, double duration, int rotation
, Handler _progressBarHandler) {
this.STORE_FRAME_DIRECTORY = storeFrameDirectory;
this.INPUT_FILE = inputVideoPath;
this.frameRate = frameRate;
this.saveWidth = saveWidth;
this.saveHeight = saveHeight;
this._progressBarHandler = _progressBarHandler;
this.duration = (int) duration;
}
/**
* Tests extraction from an MP4 to a series of PNG files.
* <p>
* We scale the video to 640x480 for the PNG just to demonstrate that we can scale the
* video with the GPU. If the input video has a different aspect ratio, we could preserve
* it by adjusting the GL viewport to get letterboxing or pillarboxing, but generally if
* you're extracting frames you don't want black bars.
*/
public void extractMpegFrames(int maxFrame, boolean fromDecode) throws IOException {
MediaCodec decoder = null;
MediaExtractor extractor = null;
MAX_FRAMES = maxFrame;
this.fromDecode = fromDecode;
try {
File inputFile = new File(INPUT_FILE); // must be an absolute path
// The MediaExtractor error messages aren't very useful. Check to see if the input
// file exists so we can throw a better one if it's not there.
if (!inputFile.canRead()) {
throw new FileNotFoundException("Unable to read " + inputFile);
}
extractor = new MediaExtractor();
extractor.setDataSource(inputFile.toString());
int trackIndex = selectTrack(extractor);
if (trackIndex < 0) {
throw new RuntimeException("No video track found in " + inputFile);
}
extractor.selectTrack(trackIndex);
MediaFormat format = extractor.getTrackFormat(trackIndex);
if (VERBOSE) {
Log.d(TAG, "Video size is " + format.getInteger(MediaFormat.KEY_WIDTH) + "x" +
format.getInteger(MediaFormat.KEY_HEIGHT));
}
// Create a MediaCodec decoder, and configure it with the MediaFormat from the
// extractor. It's very important to use the format from the extractor because
// it contains a copy of the CSD-0/CSD-1 codec-specific data chunks.
String mime = format.getString(MediaFormat.KEY_MIME);
decoder = MediaCodec.createDecoderByType(mime);
decoder.configure(format, null, null, 0);
decoder.start();
doExtract(extractor, trackIndex, decoder);
} finally {
if (decoder != null) {
decoder.stop();
decoder.release();
decoder = null;
}
if (extractor != null) {
extractor.release();
extractor = null;
}
}
}
/**
* Selects the video track, if any.
*
* @return the track index, or -1 if no video track is found.
*/
private int selectTrack(MediaExtractor extractor) {
// Select the first video track we find, ignore the rest.
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/")) {
if (VERBOSE) {
Log.d(TAG, "Extractor selected track " + i + " (" + mime + "): " + format);
}
return i;
}
}
return -1;
}
/**
* Work loop.
*/
public void doExtract(MediaExtractor extractor, int trackIndex, MediaCodec decoder) throws IOException {
final int TIMEOUT_USEC = 10000;
ByteBuffer[] decoderInputBuffers = decoder.getInputBuffers();
MediaCodec.BufferInfo info = new MediaCodec.BufferInfo();
int inputChunk = 0;
decodeCount = 0;
long frameSaveTime = 0;
boolean outputDone = false;
boolean inputDone = false;
ByteBuffer[] decoderOutputBuffers = decoder.getOutputBuffers();
MediaFormat decoderOutputFormat = null;
long rawSize = 0;
while (!outputDone) {
if (VERBOSE) Log.d(TAG, "loop");
// Feed more data to the decoder.
if (!inputDone) {
int inputBufIndex = decoder.dequeueInputBuffer(TIMEOUT_USEC);
if (inputBufIndex >= 0) {
ByteBuffer inputBuf = decoderInputBuffers[inputBufIndex];
// Read the sample data into the ByteBuffer. This neither respects nor
// updates inputBuf's position, limit, etc.
int chunkSize = extractor.readSampleData(inputBuf, 0);
if (chunkSize < 0) {
// End of stream -- send empty frame with EOS flag set.
decoder.queueInputBuffer(inputBufIndex, 0, 0, 0L,
MediaCodec.BUFFER_FLAG_END_OF_STREAM);
inputDone = true;
if (VERBOSE) Log.d(TAG, "sent input EOS");
} else {
if (extractor.getSampleTrackIndex() != trackIndex) {
Log.w(TAG, "WEIRD: got sample from track " +
extractor.getSampleTrackIndex() + ", expected " + trackIndex);
}
long presentationTimeUs = extractor.getSampleTime();
decoder.queueInputBuffer(inputBufIndex, 0, chunkSize,
presentationTimeUs, 0 /*flags*/);
if (VERBOSE) {
Log.d(TAG, "submitted frame " + inputChunk + " to dec, size=" +
chunkSize);
}
inputChunk++;
extractor.advance();
}
} else {
if (VERBOSE) Log.d(TAG, "input buffer not available");
}
}
if (!outputDone) {
int decoderStatus = decoder.dequeueOutputBuffer(info, TIMEOUT_USEC);
if (decoderStatus == MediaCodec.INFO_TRY_AGAIN_LATER) {
// no output available yet
if (VERBOSE) Log.d(TAG, "no output from decoder available");
} else if (decoderStatus == MediaCodec.INFO_OUTPUT_BUFFERS_CHANGED) {
// not important for us, since we're using Surface
if (VERBOSE) Log.d(TAG, "decoder output buffers changed");
decoderOutputBuffers = decoder.getOutputBuffers();
} else if (decoderStatus == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED) {
MediaFormat newFormat = decoder.getOutputFormat();
decoderOutputFormat = newFormat;
if (VERBOSE) Log.d(TAG, "decoder output format changed: " + newFormat);
} else if (decoderStatus < 0) {
Log.e(TAG, "unexpected result from decoder.dequeueOutputBuffer: " + decoderStatus);
} else { // decoderStatus >= 0
if (VERBOSE) Log.d(TAG, "surface decoder given buffer " + decoderStatus +
" (size=" + info.size + ")");
if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
if (VERBOSE) Log.d(TAG, "output EOS");
outputDone = true;
}
ByteBuffer outputFrame = decoderOutputBuffers[decoderStatus];
outputFrame.position(info.offset);
outputFrame.limit(info.offset + info.size);
rawSize += info.size;
if (info.size == 0) {
if (VERBOSE) Log.d(TAG, "got empty frame");
} else {
// if it's decode then check the altered value
// else save the frames
if (fromDecode) {
outputFrame.rewind();
byte[] data = new byte[outputFrame.remaining()];
outputFrame.get(data);
int size = saveWidth * saveHeight;
int offset = size;
int[] pixels = new int[size];
int u, v, y1, y2, y3, y4;
int uvIndex = 0;
if (decodeCount == 1) {
// i percorre os Y and the final pixels
// k percorre os pixles U e V
for (int i = 0, k = 0; i < size; i += 2, k += 2) {
y1 = data[i] & 0xff;
y2 = data[i + 1] & 0xff;
y3 = data[saveWidth + i] & 0xff;
y4 = data[saveWidth + i + 1] & 0xff;
u = data[offset + k] & 0xff;
v = data[offset + k + 1] & 0xff;
// getting size
if (uvIndex == 0) {
int specialByte1P1 = u & 15;
int specialByte1P2 = v & 15;
int specialCharacter1 = (specialByte1P1 << 4) | specialByte1P2;
if (specialCharacter1 != 17) {
throw new IllegalArgumentException("value has changed");
}
}
uvIndex++;
if (i != 0 && (i + 2) % saveWidth == 0)
i += saveWidth;
}
}
} else {
outputFrame.rewind();
byte[] data = new byte[outputFrame.remaining()];
outputFrame.get(data);
try {
File outputFile = new File(STORE_FRAME_DIRECTORY,
String.format(Locale.US, "frame_%d.frame", decodeCount));
FileOutputStream stream = new FileOutputStream(outputFile.getAbsoluteFile());
stream.write(data);
} catch (FileNotFoundException e1) {
e1.printStackTrace();
}
}
decodeCount++;
}
if ((info.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
if (VERBOSE) Log.d(TAG, "output EOS");
outputDone = true;
}
decoder.releaseOutputBuffer(decoderStatus, false);
}
}
}
int numSaved = (frameRate < decodeCount) ? frameRate : decodeCount;
Log.d(TAG, "Saving " + numSaved + " frames took " +
(frameSaveTime / numSaved / 1000) + " us per frame");
}
public int getDecodeCount() {
return decodeCount;
}
}
在下面的类中，我对帧进行编码，更改（帧1）的一个u v值，在第一个u和v的lsb中存储数字17，并使用mediacodec编码器构建mp4。
public class YUVFrameBufferToVideoEncoder {
private static final String TAG = BitmapToVideoEncoder.class.getSimpleName();
private static final int ERROR_IN_PROCESS = 0;
private IBitmapToVideoEncoderCallback mCallback;
private File mOutputFile;
private Queue<File> 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 int BIT_RATE;
private static int FRAME_RATE; // Frames per second
private int frameCount;
private Handler _progressBarHandler;
private Handler _processHandler;
private static final int I_FRAME_INTERVAL = 1;
private int mGenerateIndex = 0;
private int mTrackIndex;
private boolean mNoMoreFrames = false;
private boolean mAbort = false;
//
private byte[] dataToHide;
public interface IBitmapToVideoEncoderCallback {
void onEncodingComplete(File outputFile);
}
public YUVFrameBufferToVideoEncoder(IBitmapToVideoEncoderCallback callback) {
mCallback = callback;
}
public boolean isEncodingStarted() {
return (mediaCodec != null) && (mediaMuxer != null) && !mNoMoreFrames && !mAbort;
}
public int getActiveBitmaps() {
return mEncodeQueue.size();
}
public boolean startEncoding(int width, int height, int fps, int bitrate, int frameCount
, byte[] dataToHide, Handler _progressBarHandler, Handler _processHandler
, File outputFile) {
mWidth = width;
mHeight = height;
FRAME_RATE = fps;
BIT_RATE = bitrate;
this.frameCount = frameCount;
this._progressBarHandler = _progressBarHandler;
this._processHandler = _processHandler;
mOutputFile = outputFile;
this.dataToHide = dataToHide;
String outputFileString;
try {
outputFileString = outputFile.getCanonicalPath();
} catch (IOException e) {
Log.e(TAG, "Unable to get path for " + outputFile);
ErrorManager.getInstance().addErrorMessage("Unable to get path for " + outputFile);
return false;
}
MediaCodecInfo codecInfo = selectCodec(MIME_TYPE);
if (codecInfo == null) {
Log.e(TAG, "Unable to find an appropriate codec for " + MIME_TYPE);
ErrorManager.getInstance().addErrorMessage("Unable to find an appropriate codec for " + MIME_TYPE);
return false;
}
Log.d(TAG, "found codec: " + codecInfo.getName());
int colorFormat;
try {
colorFormat = MediaCodecInfo.CodecCapabilities.COLOR_FormatYUV420SemiPlanar;
} 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());
ErrorManager.getInstance().addErrorMessage("Unable to create MediaCodec " + e.getMessage());
return false;
}
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());
ErrorManager.getInstance().addErrorMessage("MediaMuxer creation failed. " + e.getMessage());
return false;
}
Log.d(TAG, "Initialization complete. Starting encoder...");
Completable.fromAction(this::encode)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe();
return true;
}
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(File frame) {
if (mediaCodec == null || mediaMuxer == null) {
Log.d(TAG, "Failed to queue frame. Encoding not started");
return;
}
Log.d(TAG, "Queueing frame");
mEncodeQueue.add(frame);
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;
File frame = mEncodeQueue.poll();
if (frame == null) {
synchronized (mFrameSync) {
mNewFrameLatch = new CountDownLatch(1);
}
try {
mNewFrameLatch.await();
} catch (InterruptedException e) {
}
frame = mEncodeQueue.poll();
}
if (frame == null) continue;
int size = (int) frame.length();
byte[] bytesNV21 = new byte[size];
try {
BufferedInputStream buf = new BufferedInputStream(new FileInputStream(frame));
buf.read(bytesNV21, 0, bytesNV21.length);
buf.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
int offsetSize = mWidth * mHeight;
int byteNV21Offset = offsetSize;
int u, v, y1, y2, y3, y4;
//
int dataToHideLength = 0;
if (dataToHide != null)
dataToHideLength = dataToHide.length;
boolean isLastIndexInserted1 = false;
boolean isLastIndexInserted2 = false;
boolean isLastIndexInserted3 = false;
int uvIndex = 0;
int frameByteCapacity = ((mWidth * mHeight) / 4) / 20;
Log.e(TAG, "encode: dataToHideLength: " + dataToHideLength);
Log.e(TAG, "encode: frameByteCapacity: " + dataToHideLength);
//
// i percorre os Y and the final pixels
// k percorre os pixles U e V
for (int i = 0, k = 0; i < offsetSize; i += 2, k += 2) {
y1 = bytesNV21[i] & 0xff;
y2 = bytesNV21[i + 1] & 0xff;
y3 = bytesNV21[mWidth + i] & 0xff;
y4 = bytesNV21[mWidth + i + 1] & 0xff;
u = bytesNV21[byteNV21Offset + k] & 0xff;
v = bytesNV21[byteNV21Offset + k + 1] & 0xff;
// frame 1
// altering u and v for test
if (mGenerateIndex == 1) {
int Unew = u & 240;
int Vnew = v & 240;
if (uvIndex == 0) {
// used in start and end of stego bytes
int specialByte1Integer = 17;
int specialByte1P1 = specialByte1Integer & 240;
int specialByte1P2 = specialByte1Integer & 15;
// shift p1 right 4 position
specialByte1P1 = specialByte1P1 >> 4;
u = Unew | specialByte1P1;
v = Vnew | specialByte1P2;
}
bytesNV21[byteNV21Offset + k] = (byte) u;
bytesNV21[byteNV21Offset + k + 1] = (byte) v;
}
uvIndex++;
if (i != 0 && (i + 2) % mWidth == 0)
i += mWidth;
}
long TIMEOUT_USEC = 500000;
int inputBufIndex = mediaCodec.dequeueInputBuffer(TIMEOUT_USEC);
long ptsUsec = computePresentationTime(mGenerateIndex, FRAME_RATE);
if (inputBufIndex >= 0) {
final ByteBuffer inputBuffer = mediaCodec.getInputBuffers()[inputBufIndex];
inputBuffer.clear();
inputBuffer.put(bytesNV21);
mediaCodec.queueInputBuffer(inputBufIndex, 0, bytesNV21.length, ptsUsec, 0);
mGenerateIndex++;
int percentComplete = 70 + (int) ((((double) mGenerateIndex) / (frameCount)) * 30);
if (_progressBarHandler != null) {
_progressBarHandler.sendMessage(_progressBarHandler.obtainMessage(percentComplete));
}
Log.w("creatingVideo: ", "is:" + percentComplete);
}
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.getOutputBuffers()[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() {
try {
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");
}
} catch (Exception ignored) {
ErrorManager.getInstance().addErrorMessage("unsupported video file");
Message res = _processHandler.obtainMessage(ERROR_IN_PROCESS);
_processHandler.sendMessage(res);
}
}
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 long computePresentationTime(long frameIndex, int framerate) {
return 132 + frameIndex * 1000000 / framerate;
}}
输出视频创建成功，没有任何问题，但是媒体编解码器更改了更改后的测试值，我无法检索到它。
这是我的问题，这是在Android中进行视频隐写术的正确方法吗？如果这不是正确的方法，请提出建议？
隐写术具有先决条件-无损编码。
到目前为止，Android上没有可用的编解码器支持无损视频编码。
所以我担心您的LSB永远不会保持相同的后期编码/解码。
Suggestion：如果帧数不多，建议您使用无损格式。您可以将帧编码为一系列PNG图像。