Android FFMpeg应用实例(一):利用CMake方式实现视频解码MP4转YUV(附Demo源码)
本篇博文将给大家介绍一个FFMpeg在Android平台上的一个应用实例，实现视频转码格式转换。如果你还没了解如何通过CMake集成JNI开发环境和在Android Studio中集成FFMpeg，请阅读Android CMake集成JNI开发环境和Android Studio通过JNI(CMake方式)集成FFMpeg音视频处理框架。本人博客会长期更新Android FFmpeg，OpenGL和OpenCV，如果您感兴趣的话，可以关注我CSDN哦。
下面我们开始实现视频转码功能
项目结构如下
其中Java代码位于MainActivity下，C++代码位于native-lib.cpp下，在native-lib.cpp文件下调用FFmpeg库提供的函数库进行视频解码。
native-lib.cpp代码如下:
#include 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);//查找解码器
if(pCodec==NULL){
LOGE("Couldn't find Codec.\n");
return -1;
}
if(avcodec_open2(pCodecCtx, pCodec,NULL)<0){//打开解码器
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);
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){//读取一帧压缩数据
if(packet->stream_index==videoindex){
ret = avcodec_decode_video2(pCodecCtx, pFrame, &got_picture, packet);//解码一帧压缩数据
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); //Y //把H264数据写入fp_h264文件
fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv); //U
fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv); //V
//Output info
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);
}
//flush decoder
//FIX: Flush Frames remained in Codec
/**
* 当av_read_frame()循环退出的时候，实际上解码器中可能还包含剩余的几帧数据。
* 因此需要通过“ flush_decoder”将这几帧数据输出。
* “flush_decoder”功能简而言之即直接调用avcodec_decode_video2()获得AVFrame，而不再向解码器传递。
*/
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); //Y
fwrite(pFrameYUV->data[1],1,y_size/4,fp_yuv); //U
fwrite(pFrameYUV->data[2],1,y_size/4,fp_yuv); //V
//Output info
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;
}
jstring
Java_com_jacket_ffmpegandroiddecoder_MainActivity_avcodecinfo(
JNIEnv *env, jobject) {
char info[40000] = {0};
av_register_all();
AVCodec *c_temp = av_codec_next(NULL);
while (c_temp != NULL) {
if (c_temp->decode != NULL) {
sprintf(info, "%sdecode:", info);
} else {
sprintf(info, "%sencode:", info);
}
switch (c_temp->type) {
case AVMEDIA_TYPE_VIDEO:
sprintf(info, "%s(video):", info);
break;
case AVMEDIA_TYPE_AUDIO:
sprintf(info, "%s(audio):", info);
break;
default:
sprintf(info, "%s(other):", info);
break;
}
sprintf(info, "%s[%10s]\n", info, c_temp->name);
c_temp = c_temp->next;
}
return env->NewStringUTF(info);
}
}
在native-lib.cpp文件中，引入FFmpeg的库，调用FFmpeg库的相关C函数对视频流先进行分帧处理，然后对每一帧视频数据进行压缩转码处理，最后根据输出路径，生成对应的YUV文件。
MainActivity代码如下:
package com.jacket.ffmpegandroiddecoder;
import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
// Used to load the 'native-lib' library on application startup.
static {
System.loadLibrary("native-lib");
}
private Button codec;
private TextView tv_info;
private EditText editText1,editText2;
private Button btnDecoder;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
init();
}
private void init() {
codec = (Button) findViewById(R.id.btn_codec);
tv_info= (TextView) findViewById(R.id.tv_info);
editText1 = (EditText) findViewById(R.id.editText1);
editText2 = (EditText) findViewById(R.id.editText2);
btnDecoder= (Button) findViewById(R.id.button);
codec.setOnClickListener(this);
btnDecoder.setOnClickListener(this);
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.btn_codec:
tv_info.setText(avcodecinfo());
break;
case R.id.button:
startDecode();
break;
default:
break;
}
}
private void startDecode() {
///sdcard/ych/videotemp/2018-03-23_1521792056455_camera.mp4
String folderurl= Environment.getExternalStorageDirectory().getPath()+"/ych/videotemp";
// String inputurl=folderurl+"/"+editText1.getText().toString();
String inputurl=folderurl+"/"+"2018-03-23_1521792056455_camera.mp4";
String outputurl=folderurl+"/"+editText2.getText().toString();
Log.e("ws-----------inputurl",inputurl);
Log.e("ws------------outputurl",outputurl);
decode(inputurl,outputurl);
}
public native int decode(String inputurl, String outputurl);
public native String avcodecinfo();
}
拷贝视频ws2.mp4到手机SD卡下，进行编译转码即可得到对应的YUV文件
运行结果如下:
本篇博文源码在github，喜欢给个star，谢谢