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Android Studio FFmpeg视频解码播放

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JasonXiao
2016.10.26 00:36* 字数 328

Android FFmpeg视频播放

本文介绍了使用Native Window和FFmpeg在Android平台上实现音频解码播放功能的方法。

Native Window简介

从Android API level 9开始,Android NDK支持native代码直接操控native window的像素缓存。这无疑方便了我们直接在native层操控界面显示。

准备工作

  1. 搭建Android Studio NDK开发环境
  2. 编译FFmpeg库并将之集成到Android Studio中
  3. 在工程的AndroidManifest中加入权限
<!-- RECORD_AUDIO is needed to create an audio recorder -->
<uses-permission android:name="android.permission.RECORD_AUDIO"/>
<!-- MODIFY_AUDIO_SETTINGS is needed to use audio effects such as environmental reverb -->
<uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/>
<!-- INTERNET is needed to use a URI-based audio player, depending on the URI -->
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

FFmpeg视频解码播放

  1. 在native-lib中加入相关的库
extern "C"{
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libswresample/swresample.h"
#include "libavutil/opt.h"
#include "libavutil/imgutils.h"
};
  1. 声明变量
static AVPacket *vPacket;
static AVFrame *vFrame, *pFrameRGBA;
static AVCodecContext *vCodecCtx;
struct SwsContext *img_convert_ctx;
static AVFormatContext *pFormatCtx;
ANativeWindow* nativeWindow;
ANativeWindow_Buffer windowBuffer;
uint8_t *v_out_buffer;
  1. 初始化FFmpeg,读取音频文件,创建解码器并解码播放
extern "C"
int
Java_cn_jx_audiotest_MainActivity_play(JNIEnv* env, jclass clazz, jstring url, jobject surface) {
    int i;
    AVCodec *vCodec;
    char input_str[500]={0};
    //读取输入的视频频文件地址
    sprintf(input_str, "%s", env->GetStringUTFChars(url, NULL));
    //初始化
    av_register_all();
    //分配一个AVFormatContext结构
    pFormatCtx = avformat_alloc_context();
    //打开文件
    if(avformat_open_input(&pFormatCtx,input_str,NULL,NULL)!=0){
        LOGD("Couldn't open input stream.\n");
        return -1;
    }
    //查找文件的流信息
    if(avformat_find_stream_info(pFormatCtx,NULL)<0){
        LOGD("Couldn't find stream information.\n");
        return -1;
    }
    //在流信息中找到视频流
    int videoindex = -1;
    for(i=0; i<pFormatCtx->nb_streams; i++) {
        if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            videoindex = i;
            break;
        }
    }
    if(videoindex == -1){
        LOGD("Couldn't find a video stream.\n");
        return -1;
    }
    //获取相应视频流的解码器
    vCodecCtx=pFormatCtx->streams[videoindex]->codec;
    vCodec = avcodec_find_decoder(vCodecCtx->codec_id);
    assert(vCodec != NULL);
    //打开解码器
    if(avcodec_open2(vCodecCtx, vCodec,NULL)<0){
        LOGD("Couldn't open codec.\n");
        return -1;
    }
    //获取界面传下来的surface
    nativeWindow = ANativeWindow_fromSurface(env, surface);
    if (0 == nativeWindow){
        LOGD("Couldn't get native window from surface.\n");
        return -1;
    }
    int width = vCodecCtx->width;
    int height = vCodecCtx->height;
    //分配一个帧指针,指向解码后的原始帧
    vFrame = av_frame_alloc();
    vPacket = (AVPacket *)av_malloc(sizeof(AVPacket));
    pFrameRGBA = av_frame_alloc();
    //绑定输出buffer
    int numBytes = av_image_get_buffer_size(AV_PIX_FMT_RGBA, width, height, 1);
    v_out_buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
    av_image_fill_arrays(pFrameRGBA->data, pFrameRGBA->linesize, v_out_buffer, AV_PIX_FMT_RGBA, width, height, 1);
    img_convert_ctx = sws_getContext(width, height, vCodecCtx->pix_fmt,
                                     width, height, AV_PIX_FMT_RGBA, SWS_BICUBIC, NULL, NULL, NULL);
    if (0 > ANativeWindow_setBuffersGeometry(nativeWindow,width,height,WINDOW_FORMAT_RGBA_8888)){
        LOGD("Couldn't set buffers geometry.\n");
        ANativeWindow_release(nativeWindow);
        return -1;
    }
    //读取帧
    while(av_read_frame(pFormatCtx, vPacket)>=0){
        if(vPacket->stream_index==videoindex){
            //视频解码
            int ret = avcodec_send_packet(vCodecCtx, vPacket);
            if (ret < 0 && ret != AVERROR(EAGAIN) && ret != AVERROR_EOF)
                return -1;
            ret = avcodec_receive_frame(vCodecCtx, vFrame);
            if (ret < 0 && ret != AVERROR_EOF)
                return -1;
            //转化格式
            sws_scale(img_convert_ctx, (const uint8_t* const*)vFrame->data, vFrame->linesize, 0, vCodecCtx->height,
                      pFrameRGBA->data, pFrameRGBA->linesize);
            if (ANativeWindow_lock(nativeWindow, &windowBuffer, NULL) < 0) {
                LOGD("cannot lock window");
            } else {
                //将图像绘制到界面上,注意这里pFrameRGBA一行的像素和windowBuffer一行的像素长度可能不一致
                //需要转换好,否则可能花屏
                uint8_t *dst = (uint8_t *) windowBuffer.bits;
                for (int h = 0; h < height; h++)
                {
                    memcpy(dst + h * windowBuffer.stride * 4,
                           v_out_buffer + h * pFrameRGBA->linesize[0],
                           pFrameRGBA->linesize[0]);
                }
                ANativeWindow_unlockAndPost(nativeWindow);

            }
        }
        av_packet_unref(vPacket);
    }
    //释放内存    
    sws_freeContext(img_convert_ctx);
    av_free(vPacket);  
    av_free(pFrameRGBA);
    avcodec_close(vCodecCtx);
    avformat_close_input(&pFormatCtx);
    return 0;
}

JAVA层调用

我们在JAVA层定义好JNI接口,并按照顺序调用即可开始播放视频文件了。

  1. 加载so库,定义JNI接口
static {
    System.loadLibrary("native-lib");
}
public native void play(String url, Surface surface);
  1. 界面创建一个SurfaceView,当界面准备好时传到native层供播放使用
surfaceView = (SurfaceView) findViewById(R.id.surface);
surfaceViewHolder = surfaceView.getHolder();
surfaceViewHolder.addCallback(new SurfaceHolder.Callback() {
    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        //获取文件路径,这里将文件放置在手机根目录下
        String folderurl = Environment.getExternalStorageDirectory().getPath();
        String inputurl = folderurl+"/someVideo.mp4";
        play(inputurl, surfaceViewHolder.getSurface());
    }
    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {    }
    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {    }
});

注意点

  1. 将图像绘制到界面上时,pFrameRGBA一行的像素和windowBuffer一行的像素长度可能不一致,需要一行一行的复制,否则会花屏或者显示多个重叠的图像。

工程代码

EasyPlayer

参考资料

  1. 100行代码实现最简单的基于FFMPEG+SDL的视频播放器(SDL1.x)
Android FFmpeg播放器制作
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