最简单的基于FFmpeg的移动端例子：Android 视频解码器-单个库版
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本文记录另一个安卓平台下基于FFmpeg的视频解码器。与前一篇文章记录的解码器不同，本文记录的解码器不再使用libavcodec.so、libavformat.so等类库，而只使用了一个类库——libffmpeg.so。该视频解码器C语言的源代码来自于《最简单的基于FFMPEG+SDL的视频播放器》。相关的概念就不再重复记录了。
FFmpeg类库的打包
记录一下FFmpeg类库打包的方法。Android平台下FFmpeg类库一共包含下面几个：libavformat-56.so
libavcodec-56.so
libavfilter-5.so
libavdevice-56.so
libavutil-54.so
libpostproc-53.so
libswresample-1.so
libswscale-3.so
由于数目繁多，直接使用这些类库还是比较麻烦的。因此可以将它们合并为一个类库。具体打包的命令就是下面脚本中“make install”后面的那个命令。- cd ffmpeg
-
- make clean
-
- export NDK=/home/leixiaohua1020/cdtworkspace/android-ndk-r9d
- export PREBUILT=$NDK/toolchains/arm-linux-androideabi-4.8/prebuilt
- export PLATFORM=$NDK/platforms/android-8/arch-arm
- export PREFIX=../ff-pure-onelib
- build_one(){
- ./configure --target-os=linux --prefix=$PREFIX \
- --enable-cross-compile \
- --enable-runtime-cpudetect \
- --disable-asm \
- --arch=arm \
- --cc=$PREBUILT/linux-x86_64/bin/arm-linux-androideabi-gcc \
- --cross-prefix=$PREBUILT/linux-x86_64/bin/arm-linux-androideabi- \
- --disable-stripping \
- --nm=$PREBUILT/linux-x86_64/bin/arm-linux-androideabi-nm \
- --sysroot=$PLATFORM \
- --enable-gpl --enable-static --disable-shared --enable-nonfree --enable-version3 --enable-small \
- --enable-zlib --disable-ffprobe --disable-ffplay --disable-ffmpeg --disable-ffserver --disable-debug \
- --extra-cflags="-fPIC -DANDROID -D__thumb__ -mthumb -Wfatal-errors -Wno-deprecated -mfloat-abi=softfp -marm -march=armv7-a"
- }
-
- build_one
-
- make
- make install
-
- $PREBUILT/linux-x86_64/bin/arm-linux-androideabi-ld -rpath-link=$PLATFORM/usr/lib -L$PLATFORM/usr/lib -L$PREFIX/lib -soname libffmpeg.so -shared -nostdlib -Bsymbolic --whole-archive --no-undefined -o $PREFIX/libffmpeg.so libavcodec/libavcodec.a libavfilter/libavfilter.a libswresample/libswresample.a libavformat/libavformat.a libavutil/libavutil.a libswscale/libswscale.a libpostproc/libpostproc.a libavdevice/libavdevice.a -lc -lm -lz -ldl -llog --dynamic-linker=/system/bin/linker $PREBUILT/linux-x86_64/lib/gcc/arm-linux-androideabi/4.8/libgcc.a
-
- cd ..
需要注意：
（1）与前面记录的脚本不同，这个脚本不再需要修改Configure的内容（生成的是*.a而不是*.so，并没有涉及到版本号问题）。
（2）前文记录的脚本里面Configure的时候是“--enable-shared --disable-static”，这个脚本里面Configure的时候设置的是“--enable-static --disable-shared”。编译完成后生成的是：
libavcodec.a
libavfilter.a
libswresample.a
libavformat.a
libavutil.a
libswscale.a
libpostproc.a
libavdevice.a
该脚本运行完后，会把上述的*.a文件打包为1个*.so文件：
libffmpeg.so
合并后的类库使用起来和合并前的类库使用方法没有区别。
源代码
项目的目录结构如图所示。Java源代码位于src目录，而C代码位于jni目录。Android程序Java端代码位于src\com\leixiaohua1020\sffmpegandroiddecoder\MainActivity.java，如下所示。-
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- package com.leixiaohua1020.sffmpegandroiddecoder;
-
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- import android.os.Bundle;
- import android.os.Environment;
- import android.app.Activity;
- import android.text.Editable;
- import android.util.Log;
- import android.view.Menu;
- import android.view.View;
- import android.view.View.OnClickListener;
- import android.widget.Button;
- import android.widget.EditText;
- import android.widget.TextView;
-
- public class MainActivity extends Activity {
-
-
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.activity_main);
-
- Button startButton = (Button) this.findViewById(R.id.button_start);
- final EditText urlEdittext_input= (EditText) this.findViewById(R.id.input_url);
- final EditText urlEdittext_output= (EditText) this.findViewById(R.id.output_url);
-
- startButton.setOnClickListener(new OnClickListener() {
- public void onClick(View arg0){
-
- String folderurl=Environment.getExternalStorageDirectory().getPath();
-
- String urltext_input=urlEdittext_input.getText().toString();
- String inputurl=folderurl+"/"+urltext_input;
-
- String urltext_output=urlEdittext_output.getText().toString();
- String outputurl=folderurl+"/"+urltext_output;
-
- Log.i("inputurl",inputurl);
- Log.i("outputurl",outputurl);
-
- decode(inputurl,outputurl);
-
- }
- });
- }
-
- @Override
- public boolean onCreateOptionsMenu(Menu menu) {
-
- getMenuInflater().inflate(R.menu.main, menu);
- return true;
- }
-
-
- public native int decode(String inputurl, String outputurl);
-
- static{
- System.loadLibrary("ffmpeg");
- System.loadLibrary("sffdecoder");
- }
- }
C语言端源代码位于jni/simplest_ffmpeg_decoder.c，如下所示。
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- #include <stdio.h>
- #include <time.h>
-
- #include "libavcodec/avcodec.h"
- #include "libavformat/avformat.h"
- #include "libswscale/swscale.h"
- #include "libavutil/log.h"
-
- #ifdef ANDROID
- #include <jni.h>
- #include <android/log.h>
- #define LOGE(format, ...) __android_log_print(ANDROID_LOG_ERROR, "(>_<)", format, ##__VA_ARGS__)
- #define LOGI(format, ...) __android_log_print(ANDROID_LOG_INFO, "(^_^)", format, ##__VA_ARGS__)
- #else
- #define LOGE(format, ...) printf("(>_<) " format "\n", ##__VA_ARGS__)
- #define LOGI(format, ...) printf("(^_^) " format "\n", ##__VA_ARGS__)
- #endif
-
-
-
- void custom_log(void *ptr, int level, const char* fmt, va_list vl){
- FILE *fp=fopen("/storage/emulated/0/av_log.txt","a+");
- if(fp){
- vfprintf(fp,fmt,vl);
- fflush(fp);
- fclose(fp);
- }
- }
-
- JNIEXPORT jint JNICALL Java_com_leixiaohua1020_sffmpegandroiddecoder_MainActivity_decode
- (JNIEnv *env, jobject obj, jstring input_jstr, jstring output_jstr)
- {
- AVFormatContext *pFormatCtx;
- int i, videoindex;
- AVCodecContext *pCodecCtx;
- AVCodec *pCodec;
- AVFrame *pFrame,*pFrameYUV;
- uint8_t *out_buffer;
- AVPacket *packet;
- int y_size;
- int ret, got_picture;
- struct SwsContext *img_convert_ctx;
- FILE *fp_yuv;
- int frame_cnt;
- clock_t time_start, time_finish;
- double time_duration = 0.0;
-
- char input_str[500]={0};
- char output_str[500]={0};
- char info[1000]={0};
- sprintf(input_str,"%s",(*env)->GetStringUTFChars(env,input_jstr, NULL));
- sprintf(output_str,"%s",(*env)->GetStringUTFChars(env,output_jstr, NULL));
-
-
- av_log_set_callback(custom_log);
-
- av_register_all();
- avformat_network_init();
- pFormatCtx = avformat_alloc_context();
-
- if(avformat_open_input(&pFormatCtx,input_str,NULL,NULL)!=0){
- LOGE("Couldn't open input stream.\n");
- return -1;
- }
- if(avformat_find_stream_info(pFormatCtx,NULL)<0){
- LOGE("Couldn't find stream information.\n");
- return -1;
- }
- videoindex=-1;
- for(i=0; i<pFormatCtx->nb_streams; i++)
- if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO){
- videoindex=i;
- break;
- }
- if(videoindex==-1){
- LOGE("Couldn't find a video stream.\n");
- return -1;
- }
- pCodecCtx=pFormatCtx->streams[videoindex]->codec;
- pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
- if(pCodec==NULL){
- LOGE("Couldn't find Codec.\n");
- return -1;
- }
- if(avcodec_open2(pCodecCtx, pCodec,NULL)<0){
- LOGE("Couldn't open codec.\n");
- return -1;
- }
-
- pFrame=av_frame_alloc();
- pFrameYUV=av_frame_alloc();
- out_buffer=(unsigned char *)av_malloc(av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height,1));
- av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize,out_buffer,
- AV_PIX_FMT_YUV420P,pCodecCtx->width, pCodecCtx->height,1);
-
- packet=(AVPacket *)av_malloc(sizeof(AVPacket));
-
- 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);
-
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- sprintf(info, "[Input ]%s\n", input_str);
- sprintf(info, "%s[Output ]%s\n",info,output_str);
- sprintf(info, "%s[Format ]%s\n",info, pFormatCtx->iformat->name);
- sprintf(info, "%s[Codec ]%s\n",info, pCodecCtx->codec->name);
- sprintf(info, "%s[Resolution]%dx%d\n",info, pCodecCtx->width,pCodecCtx->height);
-
-
- fp_yuv=fopen(output_str,"wb+");
- if(fp_yuv==NULL){
- printf("Cannot open output file.\n");
- return -1;
- }
-
- frame_cnt=0;
- time_start = clock();
-
- while(av_read_frame(pFormatCtx, packet)>=0){
- if(packet->stream_index==videoindex){
- ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
- if(ret < 0){
- LOGE("Decode Error.\n");
- return -1;
- }
- if(got_picture){
- sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
- pFrameYUV->data, pFrameYUV->linesize);
-
- y_size=pCodecCtx->width*pCodecCtx->height;
- fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);
- fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);
- fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);
-
- char pictype_str[10]={0};
- switch(pFrame->pict_type){
- case AV_PICTURE_TYPE_I:sprintf(pictype_str,"I");break;
- case AV_PICTURE_TYPE_P:sprintf(pictype_str,"P");break;
- case AV_PICTURE_TYPE_B:sprintf(pictype_str,"B");break;
- default:sprintf(pictype_str,"Other");break;
- }
- LOGI("Frame Index: %5d. Type:%s",frame_cnt,pictype_str);
- frame_cnt++;
- }
- }
- av_free_packet(packet);
- }
-
-
- while (1) {
- ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);
- if (ret < 0)
- break;
- if (!got_picture)
- break;
- sws_scale(img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0, pCodecCtx->height,
- pFrameYUV->data, pFrameYUV->linesize);
- int y_size=pCodecCtx->width*pCodecCtx->height;
- fwrite(pFrameYUV->data[0],1,y_size,fp_yuv);
- fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv);
- fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv);
-
- char pictype_str[10]={0};
- switch(pFrame->pict_type){
- case AV_PICTURE_TYPE_I:sprintf(pictype_str,"I");break;
- case AV_PICTURE_TYPE_P:sprintf(pictype_str,"P");break;
- case AV_PICTURE_TYPE_B:sprintf(pictype_str,"B");break;
- default:sprintf(pictype_str,"Other");break;
- }
- LOGI("Frame Index: %5d. Type:%s",frame_cnt,pictype_str);
- frame_cnt++;
- }
- time_finish = clock();
- time_duration=(double)(time_finish - time_start);
-
- sprintf(info, "%s[Time ]%fms\n",info,time_duration);
- sprintf(info, "%s[Count ]%d\n",info,frame_cnt);
-
- sws_freeContext(img_convert_ctx);
-
- fclose(fp_yuv);
-
- av_frame_free(&pFrameYUV);
- av_frame_free(&pFrame);
- avcodec_close(pCodecCtx);
- avformat_close_input(&pFormatCtx);
-
- return 0;
- }
Android.mk文件位于jni/Android.mk，如下所示。
- # Android.mk for FFmpeg
- #
- # Lei Xiaohua 雷霄骅
- # leixiaohua1020@126.com
- # http://blog.csdn.net/leixiaohua1020
- #
-
- LOCAL_PATH := $(call my-dir)
-
- # FFmpeg library
- include $(CLEAR_VARS)
- LOCAL_MODULE := ffmpeg
- LOCAL_SRC_FILES := libffmpeg.so
- include $(PREBUILT_SHARED_LIBRARY)
-
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- # Program
- include $(CLEAR_VARS)
- LOCAL_MODULE := sffdecoder
- LOCAL_SRC_FILES :=simplest_ffmpeg_decoder.c
- LOCAL_C_INCLUDES += $(LOCAL_PATH)/include
- LOCAL_LDLIBS := -llog -lz
- LOCAL_SHARED_LIBRARIES := ffmpeg
- include $(BUILD_SHARED_LIBRARY)
运行结果
App在手机上运行后的结果如下图所示。注意需要把等待解码的视频文件拷贝至存储卡相应的目录中。例如对于上述截图的情况，需要将sintel.mp4拷贝至存储卡的根目录中。
单击“Start”按钮就可以将存储卡根目录中的视频文件解码为YUV文件（需要等待一段时间完成解码）。注意解码后的YUV文件体积巨大，可能会占用大量的存储卡空间。
下载
simplest ffmpeg mobile
项目主页
Github：https://github.com/leixiaohua1020/simplest_ffmpeg_mobile
开源中国：https://git.oschina.net/leixiaohua1020/simplest_ffmpeg_mobile
SourceForge：https://sourceforge.net/projects/simplestffmpegmobile/
CSDN工程下载地址：http://download.csdn.net/detail/leixiaohua1020/8924391
本解决方案包含了使用FFmpeg在移动端处理多媒体的各种例子：[Android]
simplest_android_player: 基于安卓接口的视频播放器
simplest_ffmpeg_android_helloworld: 安卓平台下基于FFmpeg的HelloWorld程序
simplest_ffmpeg_android_decoder: 安卓平台下最简单的基于FFmpeg的视频解码器
simplest_ffmpeg_android_decoder_onelib: 安卓平台下最简单的基于FFmpeg的视频解码器-单库版
simplest_ffmpeg_android_streamer: 安卓平台下最简单的基于FFmpeg的推流器
simplest_ffmpeg_android_transcoder: 安卓平台下移植的FFmpeg命令行工具
simplest_sdl_android_helloworld: 移植SDL到安卓平台的最简单程序
[IOS]
simplest_ios_player: 基于IOS接口的视频播放器
simplest_ffmpeg_ios_helloworld: IOS平台下基于FFmpeg的HelloWorld程序
simplest_ffmpeg_ios_decoder: IOS平台下最简单的基于FFmpeg的视频解码器
simplest_ffmpeg_ios_streamer: IOS平台下最简单的基于FFmpeg的推流器
simplest_ffmpeg_ios_transcoder: IOS平台下移植的ffmpeg.c命令行工具
simplest_sdl_ios_helloworld: 移植SDL到IOS平台的最简单程序
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