如何使用MediaCodec把多张图片合成视频(Kotlin)

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1.常规合成方式

MediaCodec 是 Android 提供的 API，用于实时编解码音视频数据。它可以用于将一组图片合成成视频。

要实现图片合成视频，首先需要将图片转换为视频帧。可以使用 MediaCodec 编码器将每张图片编码为视频帧，然后使用 MediaMuxer 将这些视频帧合成为视频文件。

import android.media.MediaCodec;
import android.media.MediaCodecInfo;
import android.media.MediaCodecList;
import android.media.MediaFormat;
import android.media.MediaMuxer;
import android.os.Environment;
import android.util.Log;import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;public class ImageToVideoConverter {private static final String TAG = "ImageToVideoConverter";private static final String MIME_TYPE = "video/avc";private static final int FRAME_RATE = 10;private static final int IFRAME_INTERVAL = 1;public static void convertImagesToVideo(String[] imagePaths, String outputVideoPath) {try {MediaCodecInfo codecInfo = selectCodec(MIME_TYPE);if (codecInfo == null) {Log.e(TAG, "Unable to find codec for " + MIME_TYPE);return;}MediaFormat format = MediaFormat.createVideoFormat(MIME_TYPE, 640, 480);format.setInteger(MediaFormat.KEY_COLOR_FORMAT, MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface);format.setInteger(MediaFormat.KEY_BIT_RATE, 500000);format.setInteger(MediaFormat.KEY_FRAME_RATE, FRAME_RATE);format.setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, IFRAME_INTERVAL);MediaCodec codec = MediaCodec.createByCodecName(codecInfo.getName());codec.configure(format, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE);codec.start();MediaMuxer muxer = new MediaMuxer(outputVideoPath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4);for (int i = 0; i < imagePaths.length; i++) {MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();int inputBufferIndex = codec.dequeueInputBuffer(-1);if (inputBufferIndex >= 0) {ByteBuffer inputBuffer = codec.getInputBuffer(inputBufferIndex);inputBuffer.clear();Bitmap bitmap = BitmapFactory.decodeFile(imagePaths[i]);if (bitmap == null) {Log.e(TAG, "Failed to decode image");continue;}inputBuffer.put(convertBitmapToByteArray(bitmap));codec.queueInputBuffer(inputBufferIndex, 0, inputBuffer.position(), 0, 0);}int outputBufferIndex = codec.dequeueOutputBuffer(bufferInfo, 0);if (outputBufferIndex >= 0) {ByteBuffer outputBuffer = codec.getOutputBuffer(outputBufferIndex);muxer.writeSampleData(0, outputBuffer, bufferInfo);codec.releaseOutputBuffer(outputBufferIndex, false);}}codec.stop();codec.release();muxer.stop();muxer.release();} catch (IOException e) {e.printStackTrace();}}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 (String type : types) {if (type.equalsIgnoreCase(mimeType)) {return codecInfo;}}}return null;}private static byte[] convertBitmapToByteArray(Bitmap bitmap) {ByteArrayOutputStream stream = new ByteArrayOutputStream();bitmap.compress(Bitmap.CompressFormat.JPEG, 100, stream);return stream.toByteArray();}
}

调用方式

String[] imagePaths = {"/sdcard/image1.jpg", "/sdcard/image2.jpg", "/sdcard/image3.jpg"};
String outputVideoPath = "/sdcard/video.mp4";
ImageToVideoConverter.convertImagesToVideo(imagePaths, outputVideoPath);

2.升级版本

使用surface的方式，先把图片用canvas画布渲染，再用MediaCodec编码

fun convertImagesToVideo(imagePath: List<String>, videoPath: String, onSuccess: () -> Unit) {val mediaFormat =MediaFormat.createVideoFormat(MediaFormat.MIMETYPE_VIDEO_AVC, 1920, 1080).apply {setInteger(MediaFormat.KEY_BIT_RATE, 1920 * 1080 * 10)setInteger(MediaFormat.KEY_FRAME_RATE, 25)setInteger(MediaFormat.KEY_COLOR_FORMAT,MediaCodecInfo.CodecCapabilities.COLOR_FormatSurface)setInteger(MediaFormat.KEY_I_FRAME_INTERVAL, 1)}val muxer = MediaMuxer(videoPath, MediaMuxer.OutputFormat.MUXER_OUTPUT_MPEG_4)val codec = MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_VIDEO_AVC).apply {configure(mediaFormat, null, null, MediaCodec.CONFIGURE_FLAG_ENCODE)}val surface = codec.createInputSurface()codec.start()val startTimeSeconds = System.currentTimeMillis() / 1000Lvar newFormat = codec.outputFormatvar videoTrackIndex = muxer.addTrack(newFormat)imagePath.forEachIndexed { index, path ->val bitmap = BitmapFactory.decodeFile(path) ?: return@forEachIndexedval canvas = surface.lockCanvas(Rect(0, 0, 1920, 1080))canvas.drawBitmap(bitmap, null, Rect(0, 0, 1920, 1080), null)surface.unlockCanvasAndPost(canvas)var outputBufferIndex: Intval info = MediaCodec.BufferInfo()while (true) {outputBufferIndex = codec.dequeueOutputBuffer(info, 20 * 1000)Log.e("Codec", "outputBufferIndex=$outputBufferIndex")when {outputBufferIndex == MediaCodec.INFO_TRY_AGAIN_LATER -> {Log.e("Codec", "no output from encoder available")break}outputBufferIndex == MediaCodec.INFO_OUTPUT_FORMAT_CHANGED -> {newFormat = codec.outputFormatvideoTrackIndex = muxer.addTrack(newFormat)Log.e("Codec", "output format changes videoTrackIndex=$videoTrackIndex")muxer.start()}outputBufferIndex < 0 -> {Log.e("Codec", "outputBufferIndex=$outputBufferIndex")break}else -> {val encodedData = codec.getOutputBuffer(outputBufferIndex)if (encodedData == null) {Log.e("Codec", "encoderOutputBuffer $outputBufferIndex was null")break}if (info.size != 0) {info.presentationTimeUs = (startTimeSeconds + index) * 1000L * 1000Lif (index == imagePath.size - 1) {info.flags = MediaCodec.BUFFER_FLAG_END_OF_STREAM} else {info.flags = MediaCodec.BUFFER_FLAG_KEY_FRAME}Log.e("Codec", "videoTrackIndex=$videoTrackIndex info=$info")if (videoTrackIndex >= 0) {muxer.writeSampleData(videoTrackIndex, encodedData, info)}}codec.releaseOutputBuffer(outputBufferIndex, false)}}}}try {codec.stop()codec.release()muxer.stop()muxer.release()Log.e("Codec", "success...")} catch (e: Exception) {e.printStackTrace()}onSuccess()}

3.核心

使用MediaCodec创建虚拟图层

val surface = codec.createInputSurface()

在此Surface上使用画布渲染图片生成的bitmap

val bitmap = BitmapFactory.decodeFile(path) ?: return@forEachIndexed
val canvas = surface.lockCanvas(Rect(0, 0, 1920, 1080))
canvas.drawBitmap(bitmap, null, Rect(0, 0, 1920, 1080), null)
surface.unlockCanvasAndPost(canvas)

Rect(0, 0, 1920, 1080)坐标由图片的宽高决定，铺满可能会存在图片拉伸的问题

需要根据实际图片和合成的效果做调整。

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