Android音视频-FFmpeg视频解码

我们这一篇主要了解FFmpeg的解码API，把Mp4解码出yuv视频数据格式。其中的主要C代码参考自雷神查看，本实例的功能在上一节的一个应用里面。

在Java层声明native方法并调用

我这里第一次把在res/raw下面的mp4文件拷贝到了存储卡上面去然后调用native方法：

package com.lyman.ffmpeg_cmake;

import android.content.Context;
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.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class DecodeActivity extends AppCompatActivity {
private static final String TAG = "DecodeActivity";
private TextView mDecodeFilePathTV;
private String mDecodeFilePath;
private ProgressBar mProgressBar;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_decode);
if (!getMoveFile().exists()) {
new Thread(new Runnable() {
@Override
public void run() {
copyFilesFromRaw(DecodeActivity.this, R.raw.i_am_you,
"i_am_you.mp4",
getExternalFilesDir(Environment.DIRECTORY_MOVIES).getAbsolutePath());
}
}).start();
}
mDecodeFilePathTV = findViewById(R.id.textView);
mProgressBar = findViewById(R.id.progressBar);
}

public void onClickDecode(View view) {
if (!getMoveFile().exists()) {

4000
Toast.makeText(this, "source file not exist", Toast.LENGTH_SHORT).show();
return;
}

if (mDecodeFilePath == null) {
mDecodeFilePath = getExternalFilesDir(Environment.DIRECTORY_MOVIES).getAbsolutePath()
+ File.separator + "i_am_you.yuv";
}

mProgressBar.setVisibility(View.VISIBLE);
new Thread(new Runnable() {
@Override
public void run() {
decode(getMoveFile().getAbsolutePath(), mDecodeFilePath);
runOnUiThread(new Runnable() {
@Override
public void run() {
mProgressBar.setVisibility(View.GONE);
mDecodeFilePathTV.setText(mDecodeFilePath);
}
});
}
}).start();

}

public native int decode(String inputUrl, String outputUrl);

static {
//        System.loadLibrary("avutil-55");
//        System.loadLibrary("swresample-2");
//        System.loadLibrary("swscale-4");
//        System.loadLibrary("postproc-54");
//        System.loadLibrary("avcodec-57");
//        System.loadLibrary("avformat-57");
//        System.loadLibrary("avfilter-6");
//        System.loadLibrary("avdevice-57");
System.loadLibrary("decode-lib");
}

private File getMoveFile() {
File rootFile = getExternalFilesDir(Environment.DIRECTORY_MOVIES);
// Create the storage directory if it does not exist
if (!rootFile.exists()) {
if (!rootFile.mkdirs()) {
Log.d(TAG, "failed to create directory");
return null;
}
}

String fileName = "i_am_you.mp4";
String path = rootFile.getAbsolutePath() + File.separator + fileName;
return new File(path);
}

private void copyFilesFromRaw(Context context, int id, String fileName, String storagePath) {
InputStream inputStream = context.getResources().openRawResource(id);
File file = new File(storagePath);
if (!file.exists()) {//如果文件夹不存在，则创建新的文件夹
file.mkdirs();
}
readInputStream(storagePath + File.separator + fileName, inputStream);
}

/**
* 读取输入流中的数据写入输出流
*
* @param storagePath 目标文件路径
* @param inputStream 输入流
*/
private void readInputStream(String storagePath, InputStream inputStream) {
File file = new File(storagePath);
try {
if (!file.exists()) {
// 1.建立通道对象
FileOutputStream fos = new FileOutputStream(file);
// 2.定义存储空间
byte[] buffer = new byte[inputStream.available()];
// 3.开始读文件
int lenght = 0;
while ((lenght = inputStream.read(buffer)) != -1) {// 循环从输入流读取buffer字节
// 将Buffer中的数据写到outputStream对象中
fos.write(buffer, 0, lenght);
}
fos.flush();// 刷新缓冲区
// 4.关闭流
fos.close();
inputStream.close();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}

实现底层c代码

这个c文件和native-lib.c处于同一个目录下面，命名为decode-lib.c

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
#include <stdio.h>

#include "include/libavcodec/avcodec.h"
#include "include/libavformat/avformat.h"
#include "include/libswscale/swscale.h"
#include "include/libavutil/log.h"

#include <libavutil/imgutils.h>

#ifdef ANDROID

#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

/* Header for class com_lyman_ffmpeg_cmake_DecodeActivity */

#ifndef _Included_com_lyman_ffmpeg_cmake_DecodeActivity
#define _Included_com_lyman_ffmpeg_cmake_DecodeActivity
#ifdef __cplusplus
extern "C" {
#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);
}
}
/*
* Class:     com_lyman_ffmpeg_cmake_DecodeActivity
* Method:    decode
* Signature: (Ljava/lang/String;Ljava/lang/String;)I
*/
JNIEXPORT jint JNICALL Java_com_lyman_ffmpeg_1cmake_DecodeActivity_decode
(JNIEnv *env, jobject object, 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));

//FFmpeg av_log() callback
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);

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);    //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++;
}
}
av_free_packet(packet);
}
//flush decoder
//FIX: Flush Frames remained in Codec
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;

}

#ifdef __cplusplus
}
#endif
#endif

配置CmakeLists.txt 文件

这里接着上一章节的配置下面进行配置，添加的配置代码如下：

add_library( # Sets the name of the library.
decode-lib
# Sets the library as a shared library.
SHARED
# Provides a relative path to your source file(s).
src/main/cpp/decode-lib.c)
target_link_libraries(
native-lib
libavcodec-57
libavdevice-57
libavfilter-6
libavformat-57
libavutil-55
libpostproc-54
libswresample-2
libswscale-4
${log-lib})

target_link_libraries(
decode-lib
libavcodec-57
libavdevice-57
libavfilter-6
libavformat-57
libavutil-55
libpostproc-54
libswresample-2
libswscale-4
${log-lib})

这里趟了一个坑，刚开始的时候把新的decode-lib添加到了native-lib一起，对于target_link_libraries的理解错误了，以为是所有的so链接进来到这里配置，并不是这样，它是把第一个例如native-lib这个target链接可以使用的库文件，后面都是可以链接使用的库文件：详细参考：查看

OK到这里运行项目一起OK并且也和雷神一样解码出了yuv格式的视频数据。

项目完整代码：查看

参考链接：查看