Android 使用FFmpeg解析RTSP流,ANativeWindow渲染使用SurfaceView播放流程详解

文章目录

- ANativeWindow 介绍
- - `ANativeWindow` 的主要功能和特点
  - `ANativeWindow` 的常用函数
  - 工作流程原理图
  - 通过ANativeWindow渲染RGB纯色示例
- 播放RTSP流工作流程图
- 关键步骤解析
- - 自定义SurfaceView组件
  - native 层解码渲染
- 效果展示
- 注意事项

这篇文章涉及到jni层，以及Ffmpeg编解码原理，不了解相关观念的，可以先看相关技术介绍

传送门：

JNI入门_Trump. yang的博客-CSDN博客

音视频开发_Trump. yang的博客-CSDN博客

ANativeWindow 介绍

ANativeWindow 是 Android NDK 中的一个类，用于在 Native 层处理和渲染窗口。它提供了一组函数，用于在本地代码中直接操作 Android 视图系统，以便更高效地进行图像和视频渲染。ANativeWindow 通常与 Surface、SurfaceView 和 SurfaceTexture 等一起使用。

`ANativeWindow` 的主要功能和特点

窗口抽象层：
ANativeWindow 提供了一个窗口抽象层，使得本地代码能够直接操作窗口的像素数据。它可以从 Java 层的 Surface 对象获取，并用于渲染图像或视频。
锁定和解锁缓冲区：
通过 ANativeWindow_lock 和 ANativeWindow_unlockAndPost 函数，开发者可以锁定窗口的缓冲区进行像素操作，完成后解锁并提交缓冲区进行显示。
设置缓冲区属性：
可以使用 ANativeWindow_setBuffersGeometry 来设置缓冲区的大小和像素格式，以适应不同的渲染需求。
高效渲染：
直接在 Native 层操作窗口的缓冲区，可以减少数据传输和转换的开销，提高渲染性能。

`ANativeWindow` 的常用函数

获取 ANativeWindow 对象：
从 Java 层的 Surface 对象获取 ANativeWindow 对象。
```
ANativeWindow* ANativeWindow_fromSurface(JNIEnv* env, jobject surface);
```

设置缓冲区属性：
设置缓冲区的大小和像素格式。

int ANativeWindow_setBuffersGeometry(ANativeWindow* window, int width, int height, int format);

锁定缓冲区：
锁定窗口的缓冲区以进行像素操作。

int ANativeWindow_lock(ANativeWindow* window, ANativeWindow_Buffer* outBuffer, ARect* inOutDirtyBounds);

解锁缓冲区并提交：
解锁并提交缓冲区，显示内容。
```
int ANativeWindow_unlockAndPost(ANativeWindow* window);
```
释放 ANativeWindow 对象：
释放 ANativeWindow 对象以释放资源。
```
void ANativeWindow_release(ANativeWindow* window);
```

工作流程原理图

在这里插入图片描述

通过ANativeWindow渲染RGB纯色示例

ANativeWindow通常和SurfaceView一块使用,首先自定义一个SurfaceView组件

public class RtspPlayerView extends SurfaceView implements SurfaceHolder.Callback {private SurfaceHolder holder;public RtspPlayerView(Context context, AttributeSet attrs) {super(context, attrs);init();}public RtspPlayerView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init();}private void init() {holder = getHolder();holder.addCallback(this);holder.setFormat(PixelFormat.RGBA_8888);  //设置像素格式}@Overridepublic void surfaceCreated(SurfaceHolder holder) {Log.i("RtspPlayerView", "Surface 创建成功");//传入 RGB数据给Native层String bufferedImage = rgb2Hex(255, 255, 0);String substring = String.valueOf(bufferedImage).substring(3);int color = Integer.parseInt(substring,16);drawToSurface(holder.getSurface(),color);}public void play(String uri) {this.url = uri;}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {Log.i("RtspPlayerView", "Surface 大小或格式变化");}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {Log.i("RtspPlayerView", "Surface 销毁");}public static String  rgb2Hex(int r,int g,int b){return String.format("0xFF%02X%02X%02X", r,g,b);}public static native void drawToSurface(Surface surface, int color);}

在自定义组件中声明一个jni接口，以便于和native层的ANativeWindow交互，注意的是需要向native传递Surface对象的引用和RGB值

    public static native void drawToSurface(Surface surface, int color);

在native层实现C++代码，较为简单

extern "C"
JNIEXPORT void JNICALL
Java_com_marxist_firstjni_player_RtspPlayerView_drawToSurface(JNIEnv *env, jclass clazz,jobject surface, jint color) {ANativeWindow_Buffer nwBuffer;LOGI("ANativeWindow_fromSurface ");ANativeWindow *mANativeWindow = ANativeWindow_fromSurface(env, surface);if (mANativeWindow == NULL) {LOGE("ANativeWindow_fromSurface error");return;}LOGI("ANativeWindow_lock ");if (0 != ANativeWindow_lock(mANativeWindow, &nwBuffer, 0)) {LOGE("ANativeWindow_lock error");return;}LOGI("ANativeWindow_lock nwBuffer->format ");if (nwBuffer.format == WINDOW_FORMAT_RGBA_8888) {LOGI("nwBuffer->format == WINDOW_FORMAT_RGBA_8888 ");for (int i = 0; i < nwBuffer.height * nwBuffer.width; i++) {*((int*)nwBuffer.bits + i) = color;}}LOGI("ANativeWindow_unlockAndPost ");if (0 != ANativeWindow_unlockAndPost(mANativeWindow)) {LOGE("ANativeWindow_unlockAndPost error");return;}ANativeWindow_release(mANativeWindow);LOGI("ANativeWindow_release ");
}

运行效果：中间那块就是Surfaceview 展示了RGB颜色

在这里插入图片描述

播放RTSP流工作流程图

在这里插入图片描述

关键步骤解析

自定义SurfaceView组件

与加载纯色RGB基本一致，只有jni接口不同

package com.marxist.firstjni.player;import android.content.Context;
import android.graphics.PixelFormat;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.view.SurfaceView;public class RtspPlayerView extends SurfaceView implements SurfaceHolder.Callback {private SurfaceHolder holder;private String url;public RtspPlayerView(Context context, AttributeSet attrs) {super(context, attrs);init();}public RtspPlayerView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);init();}private void init() {holder = getHolder();holder.addCallback(this);holder.setFormat(PixelFormat.RGBA_8888);Log.i("RtspPlayerView", "我被初始化了");}@Overridepublic void surfaceCreated(SurfaceHolder holder) {Log.i("RtspPlayerView", "Surface 创建成功");
//        decodeVideo("rtsp://192.168.31.165:8554/test",getHolder().getSurface());//传入 RGB数据给Native层
//        String bufferedImage = rgb2Hex(255, 255, 0);
//        String substring = String.valueOf(bufferedImage).substring(3);
//        int color = Integer.parseInt(substring,16);
//
//        drawToSurface(holder.getSurface(),color);//if (url != null && !url.isEmpty()) {new Thread(new Runnable() {@Overridepublic void run() {decodeVideo(url, holder.getSurface());}}).start();}}public void play(String uri) {this.url = uri;}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {Log.i("RtspPlayerView", "Surface 大小或格式变化");}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {Log.i("RtspPlayerView", "Surface 销毁");}private native void decodeVideo(String rtspUrl, Surface surface);public static String  rgb2Hex(int r,int g,int b){return String.format("0xFF%02X%02X%02X", r,g,b);}public static native void drawToSurface(Surface surface, int color);}

native 层解码渲染

extern "C"
JNIEXPORT void JNICALL
Java_com_marxist_firstjni_player_RtspPlayerView_decodeVideo(JNIEnv *env, jobject thiz,jstring rtspUrl, jobject surface) {const char *uri = env->GetStringUTFChars(rtspUrl, 0);// 解码视频，解码音频类似，解码的流程类似，把之前的代码拷过来avformat_network_init();AVFormatContext *pFormatContext = NULL;int formatOpenInputRes = 0;int formatFindStreamInfoRes = 0;int audioStramIndex = -1;AVCodecParameters *pCodecParameters;AVCodec *pCodec = NULL;AVCodecContext *pCodecContext = NULL;int codecParametersToContextRes = -1;int codecOpenRes = -1;int index = 0;AVPacket *pPacket = NULL;AVFrame *pFrame = NULL;formatOpenInputRes = avformat_open_input(&pFormatContext, uri, NULL, NULL);if(formatOpenInputRes<0){LOGE("open url error : %s", av_err2str(formatOpenInputRes));return;}formatFindStreamInfoRes = avformat_find_stream_info(pFormatContext, NULL);// 查找视频流的 indexaudioStramIndex = av_find_best_stream(pFormatContext, AVMediaType::AVMEDIA_TYPE_VIDEO, -1, -1,NULL, 0);// 查找解码pCodecParameters = pFormatContext->streams[audioStramIndex]->codecpar;pCodec = avcodec_find_decoder(pCodecParameters->codec_id);// 打开解码器pCodecContext = avcodec_alloc_context3(pCodec);codecParametersToContextRes = avcodec_parameters_to_context(pCodecContext, pCodecParameters);codecOpenRes = avcodec_open2(pCodecContext, pCodec, NULL);// 1. 获取窗体ANativeWindow *pNativeWindow = ANativeWindow_fromSurface(env, surface);if(pNativeWindow == NULL){LOGE("获取窗体失败");return ;}// 2. 设置缓存区的数据ANativeWindow_setBuffersGeometry(pNativeWindow, pCodecContext->width, pCodecContext->height,WINDOW_FORMAT_RGBA_8888);// Window 缓冲区的 BufferANativeWindow_Buffer outBuffer;// 3.初始化转换上下文SwsContext *pSwsContext = sws_getContext(pCodecContext->width, pCodecContext->height,pCodecContext->pix_fmt, pCodecContext->width, pCodecContext->height,AV_PIX_FMT_RGBA, SWS_BILINEAR, NULL, NULL, NULL);AVFrame *pRgbaFrame = av_frame_alloc();int frameSize = av_image_get_buffer_size(AV_PIX_FMT_RGBA, pCodecContext->width,pCodecContext->height, 1);uint8_t *frameBuffer = (uint8_t *) malloc(frameSize);av_image_fill_arrays(pRgbaFrame->data, pRgbaFrame->linesize, frameBuffer, AV_PIX_FMT_RGBA,pCodecContext->width, pCodecContext->height, 1);pPacket = av_packet_alloc();pFrame = av_frame_alloc();while (av_read_frame(pFormatContext, pPacket) >= 0) {if (pPacket->stream_index == audioStramIndex) {// Packet 包，压缩的数据，解码成 数据int codecSendPacketRes = avcodec_send_packet(pCodecContext, pPacket);if (codecSendPacketRes == 0) {int codecReceiveFrameRes = avcodec_receive_frame(pCodecContext, pFrame);if (codecReceiveFrameRes == 0) {// AVPacket -> AVFrameindex++;LOGE("解码第 %d 帧", index);// 假设拿到了转换后的 RGBA 的 data 数据，如何渲染，把数据推到缓冲区sws_scale(pSwsContext, (const uint8_t *const *) pFrame->data, pFrame->linesize,0, pCodecContext->height, pRgbaFrame->data, pRgbaFrame->linesize);// 把数据推到缓冲区if (ANativeWindow_lock(pNativeWindow, &outBuffer, NULL) < 0) {// Handle errorLOGE("ANativeWindow_lock is ERROR");}
// Data copymemcpy(outBuffer.bits, frameBuffer, frameSize);if (ANativeWindow_unlockAndPost(pNativeWindow) < 0) {// Handle errorLOGE("ANativeWindow_unlockAndPost is ERROR");}}}}// 解引用av_packet_unref(pPacket);av_frame_unref(pFrame);}// 1. 解引用数据 data ， 2. 销毁 pPacket 结构体内存  3. pPacket = NULLav_packet_free(&pPacket);av_frame_free(&pFrame);__av_resources_destroy:if (pCodecContext != NULL) {avcodec_close(pCodecContext);avcodec_free_context(&pCodecContext);pCodecContext = NULL;}if (pFormatContext != NULL) {avformat_close_input(&pFormatContext);avformat_free_context(pFormatContext);pFormatContext = NULL;}avformat_network_deinit();env->ReleaseStringUTFChars(rtspUrl, uri);
}

在解码之前先创建ANativeWindow对象，设置缓冲区，设置像素格式一般解码出来的都是yuv 因此要转为RGB，设置转换上下文

// 1. 获取窗体
ANativeWindow *pNativeWindow = ANativeWindow_fromSurface(env, surface);
if(pNativeWindow == NULL){LOGE("获取窗体失败");return ;
}
// 2. 设置缓存区的数据
ANativeWindow_setBuffersGeometry(pNativeWindow, pCodecContext->width, pCodecContext->height,WINDOW_FORMAT_RGBA_8888);
// Window 缓冲区的 Buffer
ANativeWindow_Buffer outBuffer;
// 3.初始化转换上下文
SwsContext *pSwsContext = sws_getContext(pCodecContext->width, pCodecContext->height,pCodecContext->pix_fmt, pCodecContext->width, pCodecContext->height,AV_PIX_FMT_RGBA, SWS_BILINEAR, NULL, NULL, NULL);

在解码之后

  // 假设拿到了转换后的 RGBA 的 data 数据，如何渲染，把数据推到缓冲区sws_scale(pSwsContext, (const uint8_t *const *) pFrame->data, pFrame->linesize,0, pCodecContext->height, pRgbaFrame->data, pRgbaFrame->linesize);// 把数据推到缓冲区if (ANativeWindow_lock(pNativeWindow, &outBuffer, NULL) < 0) {// Handle errorLOGE("ANativeWindow_lock is ERROR");}
// Data copymemcpy(outBuffer.bits, frameBuffer, frameSize);if (ANativeWindow_unlockAndPost(pNativeWindow) < 0) {// Handle errorLOGE("ANativeWindow_unlockAndPost is ERROR");}

往缓冲区里传递转化好的RGB数据

锁定缓冲区，提交数据，交给Surface展示

效果展示

在这里插入图片描述

FFmpeg原生操作延迟果然很低，经测试，局域网能到140ms左右，之前调用第三方库，300ms左右

注意事项

如果闪退，发现ANativeWindow对象为空，说明Surface对象还没有创建完毕，一定要等SurfaceView 创建完毕再进行其他操作。
如果发现解码成功，SurfaceView无法显示，缓冲区操作也正常的话，说明SurfaceView显示被堵塞了，一定要放入到子线程中进行展示
上述代码也可以改成本地文件路径进行解码播放，只需要改动url即可，支持网络也支持本地

参考文章：
https://blog.csdn.net/cjzjolly/article/details/140448984
https://www.jianshu.com/p/e6f2fe8c6afd
https://blog.csdn.net/qq_45396088/article/details/124123280