ffmpeg实战教程（十）ffmpeg/camera实现最近很火的视频壁纸，相机壁纸

本篇实现一个有意思的玩意儿，视频壁纸，相机壁纸
这玩意好像现在还都是国外版本，哈哈

先上图：
视频壁纸

相机壁纸

1.动态壁纸制作的知识：

每一个动态壁纸都继承自WallpaperService，其中必须实现的抽象方法onCreateEngine，返回一个Engine对象，实际上所有的绘图与刷新都是由engine完成。如下

public class VideoLiveWallpaper extends WallpaperService {
// 实现WallpaperService必须实现的抽象方法 
public Engine onCreateEngine() {
return new VideoEngine();
    }



class VideoEngine extends Engine {


        @Override
public void onCreate(SurfaceHolder surfaceHolder) {
super.onCreate(surfaceHolder);

// 设置处理触摸事件 
            setTouchEventsEnabled(true);

        }
          }

        }

必须在清单文件中进行一些配置，比如：

<!-- 配置动态壁纸Service -->
<service android:label="@string/app_name"
android:name=".LiveWallpaper"
android:permission="android.permission.BIND_WALLPAPER">
<!-- 为动态壁纸配置intent-filter -->
<intent-filter>
<action android:name="android.service.wallpaper.WallpaperService" />
</intent-filter>
<!-- 为动态壁纸配置meta-data -->
<meta-data android:name="android.service.wallpaper"
android:resource="@xml/livewallpaper" />
</service>

 比较重要的部分首先是权限android:permission=”android.permission.BIND_WALLPAPER”；
   其次service需要响应action：android:name=”android.service.wallpaper.WallpaperService；
 接下来接收配置文件。首先在res文件夹下建立一个xml目录，和写appwidget一样。在目录下我们创建一个xml文件：

<wallpaper xmlns:android="http://schemas.android.com/apk/res/android"  
    android:settingsActivity="LiveWallPreference"  
    android:thumbnail="@drawable/ic_launcher"  
    android:description="@string/wallpaper_description"  
    />

然后启动选择壁纸的代码是这样的：

 final Intent pickWallpaper = new Intent(Intent.ACTION_SET_WALLPAPER);
        Intent chooser = Intent.createChooser(pickWallpaper, getString(R.string.choose_wallpaper));
        startActivity(chooser);

2.相机壁纸：

下面是相机壁纸实现的源码

最精华的一句： camera.setPreviewDisplay(getSurfaceHolder());
直接把相机预览数据传给WallpaperService。

package com.ws.ffmpegandroidwallpaper;

import android.hardware.Camera;
import android.service.wallpaper.WallpaperService;
import android.view.MotionEvent;
import android.view.SurfaceHolder;

import java.io.IOException;

public class CameraLiveWallpaper extends WallpaperService {

public Engine onCreateEngine() {
return new CameraEngine();
    }


    class CameraEngine extends Engine  {
private Camera camera;

@Override
public void onCreate(SurfaceHolder surfaceHolder) {
super.onCreate(surfaceHolder);

            startPreview();
// 设置处理触摸事件 
            setTouchEventsEnabled(true);

        }

@Override
public void onTouchEvent(MotionEvent event) {
super.onTouchEvent(event); 
        }

@Override
public void onDestroy() {
super.onDestroy();
            stopPreview();
        }

@Override
public void onVisibilityChanged(boolean visible) {
if (visible) {
                startPreview();
            } else {
                stopPreview();
            }
        }

/**
 * 开始预览
 */
public void startPreview() {
            camera = Camera.open();
            camera.setDisplayOrientation(90);

try {
                camera.setPreviewDisplay(getSurfaceHolder());
            } catch (IOException e) {
                e.printStackTrace();
            }
            camera.startPreview();

        }

/**
 * 停止预览
 */
public void stopPreview() {
if (camera != null) {
try {
                    camera.stopPreview();
                    camera.setPreviewCallback(null);
// camera.lock();
                    camera.release();
                } catch (Exception e) {
                    e.printStackTrace();
                }
                camera = null;
            }
        }
    }
}  

视频壁纸

实现视频壁纸的时候本来打算用mediaplayer实现，后来发现mediaplayer实现在某些机型上报JNI层错误。
于是改用ffmpeg自己实现JNI层，当然这样做的好处是可以更多的定制化，比如示例上的快速播放视频。

主要就一个函数
即把WallpaperService 的Surface传给native的play方法。

package com.ws.ffmpegandroidwallpaper;

import android.os.Handler;
import android.service.wallpaper.WallpaperService;
import android.view.MotionEvent;
import android.view.SurfaceHolder;

public class VideoLiveWallpaper extends WallpaperService {
// 实现WallpaperService必须实现的抽象方法 
public Engine onCreateEngine() {
return new VideoEngine();
    }
    class VideoEngine extends Engine {


@Override
public void onCreate(SurfaceHolder surfaceHolder) {
super.onCreate(surfaceHolder);

                    play(getSurfaceHolder().getSurface());
// 设置处理触摸事件 
            setTouchEventsEnabled(true);

        }

static {
        System.loadLibrary("native-lib");
    }
public native int play(Object surface);
}

然后JNI的play方法具体实现。

关键地方都有注释，可以结合我之前分享的ffmpeg源码看
ffmpeg源码简析（一）结构总览 ：http://blog.csdn.net/king1425/article/details/70597642

JNIEXPORT jint JNICALL
Java_com_ws_ffmpegandroidwallpaper_VideoLiveWallpaper_play
        (JNIEnv *env, jclass clazz, jobject surface) {
    LOGD("play");

// sd卡中的视频文件地址,可自行修改或者通过jni传入
//char *file_name = "/storage/emulated/0/ws.mp4";
char *file_name = "/storage/emulated/0/video.avi";

    av_register_all();

    AVFormatContext *pFormatCtx = avformat_alloc_context();

// Open video file
if (avformat_open_input(&pFormatCtx, file_name, NULL, NULL) != 0) {

        LOGD("Couldn't open file:%s\n", file_name);
return -1; // Couldn't open file
    }

// Retrieve stream information
if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
        LOGD("Couldn't find stream information.");
return -1;
    }

// Find the first video stream
int videoStream = -1, i;
for (i = 0; i < pFormatCtx->nb_streams; i++) {
if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO
            && videoStream < 0) {
            videoStream = i;
        }
    }
if (videoStream == -1) {
        LOGD("Didn't find a video stream.");
return -1; // Didn't find a video stream
    }

// Get a pointer to the codec context for the video stream
    AVCodecContext *pCodecCtx = pFormatCtx->streams[videoStream]->codec;

// Find the decoder for the video stream
    AVCodec *pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL) {
        LOGD("Codec not found.");
return -1; // Codec not found
    }

if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
        LOGD("Could not open codec.");
return -1; // Could not open codec
    }

// 获取native window
    ANativeWindow *nativeWindow = ANativeWindow_fromSurface(env, surface);

// 获取视频宽高
int videoWidth = pCodecCtx->width;
int videoHeight = pCodecCtx->height;

// 设置native window的buffer大小,可自动拉伸
    ANativeWindow_setBuffersGeometry(nativeWindow, videoWidth, videoHeight,
                                     WINDOW_FORMAT_RGBA_8888);
    ANativeWindow_Buffer windowBuffer;

if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) {
        LOGD("Could not open codec.");
return -1; // Could not open codec
    }

// Allocate video frame
    AVFrame *pFrame = av_frame_alloc();

// 用于渲染
    AVFrame *pFrameRGBA = av_frame_alloc();
if (pFrameRGBA == NULL || pFrame == NULL) {
        LOGD("Could not allocate video frame.");
return -1;
    }

// Determine required buffer size and allocate buffer
// buffer中数据就是用于渲染的,且格式为RGBA
int numBytes = av_image_get_buffer_size(AV_PIX_FMT_RGBA, pCodecCtx->width, pCodecCtx->height,
1);
    uint8_t *buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));
    av_image_fill_arrays(pFrameRGBA->data, pFrameRGBA->linesize, buffer, AV_PIX_FMT_RGBA,
                         pCodecCtx->width, pCodecCtx->height, 1);

// 由于解码出来的帧格式不是RGBA的,在渲染之前需要进行格式转换
struct SwsContext *sws_ctx = sws_getContext(pCodecCtx->width,
                                                pCodecCtx->height,
                                                pCodecCtx->pix_fmt,
                                                pCodecCtx->width,
                                                pCodecCtx->height,
                                                AV_PIX_FMT_RGBA,
                                                SWS_BILINEAR,
NULL,
NULL,
NULL);

int frameFinished;
    AVPacket packet;
while (av_read_frame(pFormatCtx, &packet) >= 0) {
// Is this a packet from the video stream?
if (packet.stream_index == videoStream) {

// Decode video frame
            avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);

// 并不是decode一次就可解码出一帧
if (frameFinished) {

// lock native window buffer
                ANativeWindow_lock(nativeWindow, &windowBuffer, 0);

// 格式转换
                sws_scale(sws_ctx, (uint8_t const *const *) pFrame->data,
                          pFrame->linesize, 0, pCodecCtx->height,
                          pFrameRGBA->data, pFrameRGBA->linesize);

// 获取stride
                uint8_t *dst = (uint8_t *) windowBuffer.bits;
int dstStride = windowBuffer.stride * 4;
                uint8_t *src = (pFrameRGBA->data[0]);
int srcStride = pFrameRGBA->linesize[0];

// 由于window的stride和帧的stride不同,因此需要逐行复制
int h;
for (h = 0; h < videoHeight; h++) {
                    memcpy(dst + h * dstStride, src + h * srcStride, srcStride);
                }

                ANativeWindow_unlockAndPost(nativeWindow);
            }

        }
        av_packet_unref(&packet);
    }

    av_free(buffer);
    av_free(pFrameRGBA);

// Free the YUV frame
    av_free(pFrame);

// Close the codecs
    avcodec_close(pCodecCtx);

// Close the video file
    avformat_close_input(&pFormatCtx);
return 0;
}
}

demo ：https://github.com/WangShuo1143368701/FFmpegAndroid/tree/master/ffmpegandroidwallpaper