Android本地视频播放器开发--视频解码

在上一章Android本地视频播放器开发--SDL编译编译中编译出sdl的支持库，当时我们使用的2.0，但是有些api被更改了，所以在以下的使用者中我们使用SDL1.3的库，这个库我会传上源码以及编译出的库，接下来这张我们使用ffmpeg解码视频文件中的视频帧同时使用SDL去显示。

1、Decodec_Video.c 这是我视频解码的文件，其中内容如下:

 

#include <stdio.h>

#include <android/log.h>



#ifdef __MINGW32__

#undef main /* Prevents SDL from overriding main() */

#endif



#include "../SDL/include/SDL.h"

#include "../SDL/include/SDL_thread.h"



#include "VideoPlayerDecode.h"

#include "../ffmpeg/libavutil/avutil.h"

#include "../ffmpeg/libavcodec/avcodec.h"

#include "../ffmpeg/libavformat/avformat.h"

#include "../ffmpeg/libswscale/swscale.h"



AVFormatContext *pFormatCtx;

int             i, videoStream;

AVCodecContext  *pCodecCtx;

AVCodec         *pCodec;

AVFrame         *pFrame;

AVPacket        packet;

int             frameFinished;

float           aspect_ratio;



static struct SwsContext *img_convert_ctx;

SDL_Surface     *screen;

SDL_Overlay	*bmp;

SDL_Rect        rect;

SDL_Event       event;





JNIEXPORT jint JNICALL Java_com_zhangjie_graduation_videopalyer_jni_VideoPlayerDecode_VideoPlayer

(JNIEnv *env, jclass clz, jstring fileName)

{

	const char* local_title = (*env)->GetStringUTFChars(env, fileName, NULL);

	av_register_all();//注册所有支持的文件格式以及编解码器

	if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {

		fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());

		exit(1);

	}

	if(avformat_open_input(&pFormatCtx, local_title, NULL, NULL) != 0)

                return -1;

	if(avformat_find_stream_info(pFormatCtx, NULL) < 0)

                return -1;

	av_dump_format(pFormatCtx, -1, local_title, 0);

	videoStream=-1;

	for(i=0; i<pFormatCtx->nb_streams; i++)

		if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) {

			videoStream=i;

			break;

		}

	if(videoStream==-1)

		return -1; // Didn't find a video stream

	// Get a pointer to the codec context for the video stream

	pCodecCtx=pFormatCtx->streams[videoStream]->codec;



	// Find the decoder for the video stream

	pCodec=avcodec_find_decoder(pCodecCtx->codec_id);

	if(pCodec==NULL) {

		fprintf(stderr, "Unsupported codec!\n");

		return -1; // Codec not found

	}

	if(avcodec_open2(pCodecCtx, pCodec, NULL) < 0)return -1;

	pFrame = avcodec_alloc_frame();

	if(pFrame == NULL)return -1;

	// Make a screen to put our video

#ifndef __DARWIN__

	screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);

#else

	screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);

#endif

	if(!screen) {

		fprintf(stderr, "SDL: could not set video mode - exiting\n");

		exit(1);

	}

	// Allocate a place to put our YUV image on that screen

	bmp = SDL_CreateYUVOverlay(pCodecCtx->width,

			pCodecCtx->height,

			SDL_YV12_OVERLAY,

			screen);

 	img_convert_ctx = sws_getContext(pCodecCtx->width,  

                          pCodecCtx->height, pCodecCtx->pix_fmt,  

                          pCodecCtx->width, pCodecCtx->height,  

                          PIX_FMT_RGB24, SWS_BICUBIC, NULL, NULL, NULL);  



	// Read frames and save first five frames to disk

	i=0;

	while(av_read_frame(pFormatCtx, &packet)>=0) {

		// Is this a packet from the video stream?

		if(packet.stream_index==videoStream) {

			avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);

			// Did we get a video frame?

			if(frameFinished) {

				SDL_LockYUVOverlay(bmp);

				

				AVPicture *pict;

				pict->data[0] = bmp->pixels[0];

				pict->data[1] = bmp->pixels[2];

				pict->data[2] = bmp->pixels[1];



				pict->linesize[0] = bmp->pitches[0];

				pict->linesize[1] = bmp->pitches[2];

				pict->linesize[2] = bmp->pitches[1];

				

sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pict->data, pict->linesize);

				SDL_UnlockYUVOverlay(bmp);



				rect.x = 0;

				rect.y = 0;

				rect.w = pCodecCtx->width;

				rect.h = pCodecCtx->height;

				SDL_DisplayYUVOverlay(bmp, &rect);



			}

		}

		// Free the packet that was allocated by av_read_frame

		av_free_packet(&packet);

		SDL_PollEvent(&event);

		switch(event.type) {

			case SDL_QUIT:

				SDL_Quit();

				exit(0);

				break;

			default:

				break;

		}



	}

	// Free the YUV frame

	av_free(pFrame);



	// Close the codec

	avcodec_close(pCodecCtx);



	// Close the video file

	av_close_input_file(pFormatCtx);

}

2、编译结果如下:

 

 

root@zhangjie:/Graduation/jni# ndk-build

Install        : libSDL.so => libs/armeabi/libSDL.so

Install        : libffmpeg-neon.so => libs/armeabi/libffmpeg-neon.so

Compile arm    : ffmpeg-test-neon <= Decodec_Video.c

/Graduation/jni/jniffmpeg/Decodec_Video.c: In function 'Java_com_zhangjie_graduation_videopalyer_jni_VideoPlayerDecode_VideoPlayer':

/Graduation/jni/jniffmpeg/Decodec_Video.c:106:1: warning: passing argument 2 of 'sws_scale' from incompatible pointer type [enabled by default]

/Graduation/jni/jniffmpeg/../ffmpeg/libswscale/swscale.h:237:5: note: expected 'uint8_t const * const*' but argument is of type 'uint8_t **'

/Graduation/jni/jniffmpeg/Decodec_Video.c:137:2: warning: 'av_close_input_file' is deprecated (declared at /Graduation/jni/jniffmpeg/../ffmpeg/libavformat/avformat.h:1533) [-Wdeprecated-declarations]

SharedLibrary  : libffmpeg-test-neon.so

Install        : libffmpeg-test-neon.so => libs/armeabi/libffmpeg-test-neon.so

3、SDL1.3源码

 

http://download.csdn.net/detail/jwzhangjie/5596453

4、之前在Android本地视频播放器开发--NDK编译FFmpeg中没有添加swscale功能，所以需要重新编译ffmpeg，其脚本如下:

 

NDK=/opt/android-ndk-r8d

PLATFORM=$NDK/platforms/android-8/arch-arm/

PREBUILT=$NDK/toolchains/arm-linux-androideabi-4.4.3/prebuilt/linux-x86

LOCAL_ARM_NEON=true

CPU=armv7-a

OPTIMIZE_CFLAGS="-mfloat-abi=softfp -mfpu=neon -marm -mcpu=cortex-a8"

PREFIX=./android/$CPU

./configure --target-os=linux \

    --prefix=$PREFIX \

    --enable-cross-compile \

    --arch=arm \

    --enable-nonfree \

    --enable-asm \

    --cpu=cortex-a8 \

    --enable-neon \

    --cc=$PREBUILT/bin/arm-linux-androideabi-gcc \

    --cross-prefix=$PREBUILT/bin/arm-linux-androideabi- \

    --nm=$PREBUILT/bin/arm-linux-androideabi-nm \

    --sysroot=$PLATFORM \

    --extra-cflags=" -O3 -fpic -DANDROID -DHAVE_SYS_UIO_H=1 $OPTIMIZE_CFLAGS " \

    --disable-shared \

    --enable-static \

    --extra-ldflags="-Wl,-rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib  -nostdlib -lc -lm -ldl -llog" \

    --disable-ffmpeg \

    --disable-ffplay \

    --disable-ffprobe \

    --disable-ffserver \

    --disable-encoders \

    --enable-avformat \

    --disable-optimizations \

    --disable-doc \

    --enable-pthreads \

    --disable-yasm \

    --enable-zlib \

    --enable-pic \

    --enable-small



#make clean

make  -j4 install



$PREBUILT/bin/arm-linux-androideabi-ar d libavcodec/libavcodec.a inverse.o



$PREBUILT/bin/arm-linux-androideabi-ld -rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib  -soname libffmpeg-neon.so -shared -nostdlib  -z noexecstack -Bsymbolic --whole-archive --no-undefined -o $PREFIX/libffmpeg-neon.so libavcodec/libavcodec.a libavformat/libavformat.a libavutil/libavutil.a  libavfilter/libavfilter.a libswresample/libswresample.a libswscale/libswscale.a libavdevice/libavdevice.a -lc -lm -lz -ldl -llog  --warn-once  --dynamic-linker=/system/bin/linker $PREBUILT/lib/gcc/arm-linux-androideabi/4.4.3/libgcc.a