如何在Android上使用FFmpeg解码图像参考文章 ，如何在Android上使用SDL2.0来显示图像参考 。有了以上两篇文章的基础我们就可以在Android使用FFmpeg来解码图像并且使用SDL2.0来显示输出的图像了。
博主的开发环境：Ubuntu 14.04 64位，Eclipse+CDT+ADT+NDK。
在文章开始之前假定你已经知道如何使用NDK编译FFmpeg，以及知道如何移植SDL2.0到Android平台上来了，如有不明白的可以参考文章开头的两篇文章。
工程中的目录结构：ffmpeg文件夹下是ffmpeg相关的头文件以及编译的Android makefile文件，SDL文件夹下面是SDL2.0相关的头文件以及相关的源码和编译用的Android makefile 文件，player文件下是用来解码与显示相关的代码和Android makefile。
一、参考 创建一个工程，创建jni文件，在jni下创建SDL文件夹，将相应的头文件以及源码拷贝过来。在这里也可以参考 将编译好的动态库作为PREBUILT_SHARED_LIBRARY来加载。SDL文件下的Android.mk内容：
LOCAL_PATH := $(call my-dir)############################# SDL shared library############################include $(CLEAR_VARS)LOCAL_MODULE := SDL2LOCAL_C_INCLUDES := $(LOCAL_PATH)/includeLOCAL_EXPORT_C_INCLUDES := $(LOCAL_C_INCLUDES)LOCAL_SRC_FILES := \ $(subst $(LOCAL_PATH)/,, \ $(wildcard $(LOCAL_PATH)/src/*.c) \ $(wildcard $(LOCAL_PATH)/src/audio/*.c) \ $(wildcard $(LOCAL_PATH)/src/audio/android/*.c) \ $(wildcard $(LOCAL_PATH)/src/audio/dummy/*.c) \ $(LOCAL_PATH)/src/atomic/SDL_atomic.c \ $(LOCAL_PATH)/src/atomic/SDL_spinlock.c.arm \ $(wildcard $(LOCAL_PATH)/src/core/android/*.c) \ $(wildcard $(LOCAL_PATH)/src/cpuinfo/*.c) \ $(wildcard $(LOCAL_PATH)/src/dynapi/*.c) \ $(wildcard $(LOCAL_PATH)/src/events/*.c) \ $(wildcard $(LOCAL_PATH)/src/file/*.c) \ $(wildcard $(LOCAL_PATH)/src/haptic/*.c) \ $(wildcard $(LOCAL_PATH)/src/haptic/dummy/*.c) \ $(wildcard $(LOCAL_PATH)/src/joystick/*.c) \ $(wildcard $(LOCAL_PATH)/src/joystick/android/*.c) \ $(wildcard $(LOCAL_PATH)/src/loadso/dlopen/*.c) \ $(wildcard $(LOCAL_PATH)/src/power/*.c) \ $(wildcard $(LOCAL_PATH)/src/power/android/*.c) \ $(wildcard $(LOCAL_PATH)/src/filesystem/dummy/*.c) \ $(wildcard $(LOCAL_PATH)/src/render/*.c) \ $(wildcard $(LOCAL_PATH)/src/render/*/*.c) \ $(wildcard $(LOCAL_PATH)/src/stdlib/*.c) \ $(wildcard $(LOCAL_PATH)/src/thread/*.c) \ $(wildcard $(LOCAL_PATH)/src/thread/pthread/*.c) \ $(wildcard $(LOCAL_PATH)/src/timer/*.c) \ $(wildcard $(LOCAL_PATH)/src/timer/unix/*.c) \ $(wildcard $(LOCAL_PATH)/src/video/*.c) \ $(wildcard $(LOCAL_PATH)/src/video/android/*.c) \ $(wildcard $(LOCAL_PATH)/src/test/*.c))LOCAL_CFLAGS += -DGL_GLEXT_PROTOTYPESLOCAL_LDLIBS := -ldl -lGLESv1_CM -lGLESv2 -llog -landroidinclude $(BUILD_SHARED_LIBRARY)############################# SDL static library#############################LOCAL_MODULE := SDL2_static#LOCAL_MODULE_FILENAME := libSDL2#LOCAL_SRC_FILES += $(LOCAL_PATH)/src/main/android/SDL_android_main.c#LOCAL_LDLIBS := #LOCAL_EXPORT_LDLIBS := -Wl,--undefined=Java_org_libsdl_app_SDLActivity_nativeInit -ldl -lGLESv1_CM -lGLESv2 -llog -landroid#include $(BUILD_STATIC_LIBRARY)
二、参考， 在工程中新建一个ffmpeg文件夹，将与ffmpeg相关的头文件include进来。ffmpeg文件夹下的Android.mk内容：
LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE := ffmpegLOCAL_SRC_FILES := /path/to/build/ffmpeg/libffmpeg.soinclude $(PREBUILT_SHARED_LIBRARY)
三、新建player文件夹，用来编写解码与显示文件。player.c文件内容：
/* * SDL_Lesson.c * * Created on: Aug 12, 2014 * Author: clarck */#include#include #include "SDL.h"#include "SDL_thread.h"#include "SDL_events.h"#include "../include/logger.h"#include "../ffmpeg/include/libavcodec/avcodec.h"#include "../ffmpeg/include/libavformat/avformat.h"#include "../ffmpeg/include/libavutil/pixfmt.h"#include "../ffmpeg/include/libswscale/swscale.h"int main(int argc, char *argv[]) { char *file_path = argv[1]; LOGI("file_path:%s", file_path); AVFormatContext *pFormatCtx; AVCodecContext *pCodecCtx; AVCodec *pCodec; AVFrame *pFrame, *pFrameYUV; AVPacket *packet; uint8_t *out_buffer; SDL_Texture *bmp = NULL; SDL_Window *screen = NULL; SDL_Rect rect; SDL_Event event; static struct SwsContext *img_convert_ctx; int videoStream, i, numBytes; int ret, got_picture; av_register_all(); pFormatCtx = avformat_alloc_context(); if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) { LOGE("Could not initialize SDL - %s. \n", SDL_GetError()); exit(1); } if (avformat_open_input(&pFormatCtx, file_path, NULL, NULL) != 0) { LOGE("can't open the file. \n"); return -1; } if (avformat_find_stream_info(pFormatCtx, NULL) < 0) { LOGE("Could't find stream infomation.\n"); return -1; } videoStream = 1; for (i = 0; i < pFormatCtx->nb_streams; i++) { if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) { videoStream = i; } } LOGI("videoStream:%d", videoStream); if (videoStream == -1) { LOGE("Didn't find a video stream.\n"); return -1; } pCodecCtx = pFormatCtx->streams[videoStream]->codec; pCodec = avcodec_find_decoder(pCodecCtx->codec_id); if (pCodec == NULL) { LOGE("Codec not found.\n"); return -1; } if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) { LOGE("Could not open codec.\n"); return -1; } pFrame = av_frame_alloc(); pFrameYUV = av_frame_alloc(); //---------------------------init sdl---------------------------// screen = SDL_CreateWindow("My Player Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, pCodecCtx->width, pCodecCtx->height, SDL_WINDOW_FULLSCREEN | SDL_WINDOW_OPENGL); SDL_Renderer *renderer = SDL_CreateRenderer(screen, -1, 0); bmp = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_YV12, SDL_TEXTUREACCESS_STREAMING, pCodecCtx->width, pCodecCtx->height); //-------------------------------------------------------------// img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL); numBytes = avpicture_get_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height); out_buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t)); avpicture_fill((AVPicture *) pFrameYUV, out_buffer, AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height); rect.x = 0; rect.y = 0; rect.w = pCodecCtx->width; rect.h = pCodecCtx->height; int y_size = pCodecCtx->width * pCodecCtx->height; packet = (AVPacket *) malloc(sizeof(AVPacket)); av_new_packet(packet, y_size); av_dump_format(pFormatCtx, 0, file_path, 0); while (av_read_frame(pFormatCtx, packet) >= 0) { if (packet->stream_index == videoStream) { ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet); if (ret < 0) { LOGE("decode error.\n"); return -1; } LOGI("got_picture:%d", got_picture); if (got_picture) { sws_scale(img_convert_ctx, (uint8_t const * const *) pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize); ////iPitch 计算yuv一行数据占的字节数 //SDL_UpdateTexture(bmp, &rect, pFrameYUV->data[0], pFrameYUV->linesize[0]); SDL_UpdateYUVTexture(bmp, &rect, pFrameYUV->data[0], pFrameYUV->linesize[0], pFrameYUV->data[1], pFrameYUV->linesize[1], pFrameYUV->data[2], pFrameYUV->linesize[2]); SDL_RenderClear(renderer); SDL_RenderCopy(renderer, bmp, &rect, &rect); SDL_RenderPresent(renderer); } SDL_Delay(50); } av_free_packet(packet); SDL_PollEvent(&event); switch (event.type) { case SDL_QUIT: SDL_Quit(); exit(0); break; default: break; } } SDL_DestroyTexture(bmp); av_free(out_buffer); av_free(pFrameYUV); avcodec_close(pCodecCtx); avformat_close_input(&pFormatCtx); return 0;}
四、编写player文件夹下面的Android makefile，内容如下：
LOCAL_PATH := $(call my-dir)include $(CLEAR_VARS)LOCAL_MODULE := playerSDL_PATH := ../SDLFFMPEG_PATH := ../ffmpegLOCAL_C_INCLUDES := $(LOCAL_PATH)/includeLOCAL_C_INCLUDES += $(LOCAL_PATH)/$(SDL_PATH)/includeLOCAL_C_INCLUDES += $(LOCAL_PATH)/$(FFMPEG_PATH)/include# Add your application source files here...LOCAL_SRC_FILES := $(SDL_PATH)/src/main/android/SDL_android_main.c LOCAL_SRC_FILES += player.cLOCAL_SHARED_LIBRARIES := SDL2LOCAL_SHARED_LIBRARIES += ffmpegLOCAL_LDLIBS := -lGLESv1_CM -lGLESv2 -lloginclude $(BUILD_SHARED_LIBRARY)
五、修改SDLActivity.java文件内容，用来加载libffmpeg.so以及libplayer.so，以及修改用来解码的文件路径。
// Load the .so static { System.loadLibrary("ffmpeg"); System.loadLibrary("SDL2"); //System.loadLibrary("SDL2_image"); //System.loadLibrary("SDL2_mixer"); //System.loadLibrary("SDL2_net"); //System.loadLibrary("SDL2_ttf"); System.loadLibrary("player"); } /** Simple nativeInit() runnable*/class SDLMain implements Runnable { @Override public void run() { // Runs SDL_main() String sdcard = Environment.getExternalStorageDirectory().getAbsolutePath(); SDLActivity.nativeInit("/sdcard/a.mp4"); //Log.v("SDL", "SDL thread terminated"); }} 工程项目截图：
运行效果截图：
