在学习雷神的android视频解码器这篇文章的时候，又不小心踩了许多坑。这不是因为雷神的博客写的不够详细，而是随着技术更新，有很多在当初看来不用关心的细节，在今天一个不小心就会出错。
问题一：No implementation found for decode
No implementation found for int com.xiaguangcheng.cmakedemo.MainActivity.decode(java.lang.String, java.lang.String) (tried Java_com_xiaguangcheng_cmakedemo_MainActivity_decode and Java_com_xiaguangcheng_cmakedemo_MainActivity_decode__Ljava_lang_String_2Ljava_lang_String_2)
这个问题是说找不到我们在cpp文件中写的实现decode的本地方法，但实际上我们已经写了。可能是因为Cmake管理的问题，我们需要在方法之前加上extern "C"
extern "C"
JNIEXPORT jint JNICALL
Java_com_fengfutong_cmakedemo_MainActivity_decode
(JNIEnv *env, jobject , jstring input_jstr, jstring output_jstr)
问题二：Couldn't open input stream.
我们根据提示在cpp中找到这段代码
if (avformat_open_input(&pFormatCtx, input_str, NULL, NULL) != 0) {
LOGE("Couldn't open input stream.\n,%s,%d",input_str,avformat_open_input(&pFormatCtx, input_str, NULL, NULL));
return -1;
}
这个问题是因为我用的项目的目标版本超过了23.
targetSdkVersion 25
因为超过了23之后，有一些危险权限是需要手动申请的。尽管你在AndroidManifest.xml中已经配置了读写sdk的权限
但是报错的时候，并没有任何提示关于permission denied。
这个时候我们只要把targetSdkVersion降低到23以下就可以了。当然也可以稍微麻烦一点点，手动申请一下权限。
下面贴上最新的native-lib.cpp和MainActivity.java代码
#include
#include
extern "C" {
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
#include "libavutil/imgutils.h"
#ifdef ANDROID
#include
#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
};
extern "C"
JNIEXPORT jstring JNICALL
Java_com_fengfutong_cmakedemo_MainActivity_stringFromJNI(JNIEnv *env,
jobject /* this */) {
char info[10000] = {0};
sprintf(info, "%s\n", avcodec_configuration());
return env->NewStringUTF(info);
}
//Output FFmpeg's av_log()
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);
}
}
extern "C"
JNIEXPORT jint JNICALL
Java_com_fengfutong_cmakedemo_MainActivity_decode
(JNIEnv *env, jobject , 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(input_jstr, NULL));
sprintf(output_str, "%s", env->GetStringUTFChars(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,%s,%d",input_str,avformat_open_input(&pFormatCtx, input_str, NULL, NULL));
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;
}
MainActivity:
public class MainActivity extends Activity {
// Used to load the 'native-lib' library on application startup.
static {
System.loadLibrary("avutil-55");
System.loadLibrary("avcodec-57");
System.loadLibrary("avformat-57");
System.loadLibrary("avdevice-57");
System.loadLibrary("swresample-2");
System.loadLibrary("swscale-4");
// System.loadLibrary("postproc-53");
System.loadLibrary("avfilter-6");
System.loadLibrary("native-lib");
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Example of a call to a native method
// TextView tv = (TextView) findViewById(R.id.sample_text);
// tv.setText(stringFromJNI());
Button button= (Button) findViewById(R.id.button);
final EditText editText= (EditText) findViewById(R.id.editText);
final EditText editText2= (EditText) findViewById(R.id.editText2);
editText.setText("sintel.mp4");
editText2.setText("1234test.yuv");
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String s = editText.getText().toString();
String s1 = editText2.getText().toString();
String absolutePath = Environment.getExternalStorageDirectory().getAbsolutePath();
String inputPath=absolutePath+"/"+s;
String outPath=absolutePath+"/"+s1;
Log.e("main",inputPath+"---->"+outPath);
decode(inputPath,outPath);
}
});
}
public native int decode(String inputPath, String outPath) ;
/**
* A native method that is implemented by the 'native-lib' native library,
* which is packaged with this application.
*/
public native String stringFromJNI();
}