项目源代码https://github.com/liluojun/PlayVideo
Android相机输出的是yuv数据、yuv数据格式太多了如420p、420sp等，我们经常会需要对yuv数据做处理，最原始的使用java for循环的方式耗时太多不合算，libyuv是由google开源的一个针对yuv数据处理的库，其效率比使用java处理的方式快太多了，故比较推荐使用。
public class NativeMethod {
public native void nv21ToI420(byte[] src, byte[] dst, int w, int h, byte[] y, byte[] u, byte[] v);
public native void nv21ToNv12(byte[] src, byte[] dst, int w, int h, byte[] y, byte[] u, byte[] v);
public native void nv21CutterToI420(byte[] src, byte[] dst, int cutter_w, int cutter_h, int w, int h, byte[] y, byte[] u, byte[] v);
public native void nv21CutterToNv12(byte[] src, byte[] dst, int cutter_w, int cutter_h, int w, int h, byte[] y, byte[] u, byte[] v);
}
我在项目中提供了4个方法示例前两个是nv21转420p和420sp，后两个是转的过程中做出裁剪。
参数说明：byte[] src 源数据
byte[] dst转换后的输出数据
int cutter_w裁剪的宽度
int cutter_h裁剪的高度
int w原宽度
int h原高度
byte[] y, byte[] u, byte[] v裁剪后yuv三个分量的数据，由于我用的是yuv渲染故需要这些值，没需求的可以不用理会。
jni层代码
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,"ffmpeg",__VA_ARGS__)
#ifndef _Included_media_jni_NativeMethod
#define _Included_media_jni_NativeMethod
#ifdef __cplusplus
extern "C" {
#include "libyuv.h"
#include
#include "media_jni_NativeMethod.h"
#endif
void releaseByteArray(JNIEnv *env, jbyteArray array, uint8_t *elems, jint mode) {
env->ReleaseByteArrayElements(array, (jbyte *) elems, mode);
env->DeleteLocalRef(array);
}
/*
* Class: media_jni_NativeMethod
* Method: nv21ToI420
* Signature: ([B[BII)V
*/
JNIEXPORT void JNICALL Java_media_jni_NativeMethod_nv21ToI420
(JNIEnv *env, jobject job, jbyteArray src, jbyteArray dst, jint w, jint h, jbyteArray y,
jbyteArray u, jbyteArray v) {
uint8_t *srcArray = (uint8_t *) env->GetByteArrayElements(src, NULL);
uint8_t *dstArray = (uint8_t *) env->GetByteArrayElements(dst, NULL);
uint8_t *yArray = (uint8_t *) env->GetByteArrayElements(y, NULL);
uint8_t *uArray = (uint8_t *) env->GetByteArrayElements(u, NULL);
uint8_t *vArray = (uint8_t *) env->GetByteArrayElements(v, NULL);
jint uvW = w >> 1;
jint ySize = w * h;
jint uSize = (uvW) * (h >> 1);
uint8_t *y_src = srcArray;
uint8_t *uv_src = srcArray + ySize;
uint8_t *y_dst = dstArray;
uint8_t *u_dst = dstArray + ySize;
uint8_t *v_dst = dstArray + ySize + uSize;
libyuv::NV21ToI420(y_src, w, uv_src, w, y_dst, w, u_dst, uvW, v_dst, uvW, w, h);
memcpy(yArray, y_dst, ySize);
memcpy(uArray, u_dst, (w * h) >> 2);
memcpy(vArray, v_dst, (w * h) >> 2);
//I420旋转方法注释但不能删除
// yuv.libyuv::I420Rotate(y_tran, w, u_tran, w >> 1, v_tran, w >> 1, y_dst, h, u_dst, h >> 1, v_dst,
// h >> 1, h, w, yuv.libyuv::kRotate270);
releaseByteArray(env, src, srcArray, 0);
releaseByteArray(env, dst, dstArray, 0);
releaseByteArray(env, y, yArray, 0);
releaseByteArray(env, v, vArray, 0);
releaseByteArray(env, u, uArray, 0);
} ;
/*
* Class: media_jni_NativeMethod
* Method: nv21ToNv12
* Signature: ([B[BII)V
*/
JNIEXPORT void JNICALL Java_media_jni_NativeMethod_nv21ToNv12
(JNIEnv *env, jobject job, jbyteArray src, jbyteArray dst, jint w, jint h, jbyteArray y,
jbyteArray u, jbyteArray v) {
LOGE("111");
uint8_t *srcArray = (uint8_t *) env->GetByteArrayElements(src, 0);
uint8_t *dstArray = (uint8_t *) env->GetByteArrayElements(dst, 0);
LOGE("222");
uint8_t *yArray = (uint8_t *) env->GetByteArrayElements(y, NULL);
uint8_t *uArray = (uint8_t *) env->GetByteArrayElements(u, NULL);
uint8_t *vArray = (uint8_t *) env->GetByteArrayElements(v, NULL);
jint ySize = w * h;
jint uvSize = (w >> 1) * (h >> 1);
uint8_t *y_src = srcArray;
uint8_t *uv_src = srcArray + ySize;
uint8_t *u_src = srcArray + ySize;
uint8_t *v_src = srcArray + ySize + uvSize;
uint8_t *y_dst = dstArray;
uint8_t *uv_dst = dstArray + ySize;
libyuv::NV21ToI420(y_src, w, uv_src, w, yArray, w, uArray, w >> 1, vArray, w >> 1, w,
h);
libyuv::I420ToNV12(yArray, w, uArray, w >> 1, vArray, w >> 1, y_dst, w, uv_dst, w, w, h);
releaseByteArray(env, src, srcArray, 0);
releaseByteArray(env, dst, dstArray, 0);
releaseByteArray(env, y, yArray, 0);
releaseByteArray(env, v, vArray, 0);
releaseByteArray(env, u, uArray, 0);
} ;
/*
* Class: media_jni_NativeMethod
* Method: nv21CutterToI420
* Signature: ([B[BIIII)V
*/
JNIEXPORT void JNICALL Java_media_jni_NativeMethod_nv21CutterToI420
(JNIEnv *env, jobject job, jbyteArray src, jbyteArray dst, jint cw, jint ch, jint w,
jint h, jbyteArray y,
jbyteArray u, jbyteArray v) {
uint8_t *srcArray = (uint8_t *) env->GetByteArrayElements(src, 0);
uint8_t *dstArray = (uint8_t *) env->GetByteArrayElements(dst, 0);
jbyteArray transitJbyteArray = env->NewByteArray(w * h * 3 / 2);
uint8_t *transitArray = (uint8_t *) env->GetByteArrayElements(transitJbyteArray, 0);
uint8_t *yArray = (uint8_t *) env->GetByteArrayElements(y, NULL);
uint8_t *uArray = (uint8_t *) env->GetByteArrayElements(u, NULL);
uint8_t *vArray = (uint8_t *) env->GetByteArrayElements(v, NULL);
jint ySize = w * h;
jint startx = (w - cw) / 2;
jint starty = (h - ch) / 2;
jint uvSize = (w >> 1) * (h >> 1);
uint8_t *y_src = srcArray;
uint8_t *uv_src = srcArray + ySize;
uint8_t *y_transit = transitArray;
uint8_t *u_transit = transitArray + ySize;
uint8_t *v_transit = transitArray + ySize + uvSize;
uint8_t *y_dst = dstArray;
uint8_t *u_dst = dstArray + (cw * ch);
uint8_t *v_dst = dstArray + (cw * ch) + ((cw * ch) >> 2);
libyuv::NV21ToI420(y_src, w, uv_src, w, y_transit, w, u_transit, w >> 1, v_transit, w >> 1, w,
h);
libyuv::ConvertToI420(transitArray, ySize + uvSize, y_dst, cw, u_dst, cw >> 1,
v_dst, cw >> 1,
startx, starty, w, h, cw, ch, libyuv::kRotate0, libyuv::FOURCC_I420);
memcpy(yArray, y_dst, cw * ch);
memcpy(uArray, u_dst, (cw * ch) >> 2);
memcpy(vArray, v_dst, (cw * ch) >> 2);
releaseByteArray(env, transitJbyteArray, transitArray, 0);
releaseByteArray(env, src, srcArray, 0);
releaseByteArray(env, dst, dstArray, 0);
releaseByteArray(env, y, yArray, 0);
releaseByteArray(env, v, vArray, 0);
releaseByteArray(env, u, uArray, 0);
} ;
/*
* Class: media_jni_NativeMethod
* Method: nv21CutterToNv12
* Signature: ([B[BIIII)V
*/
JNIEXPORT void JNICALL Java_media_jni_NativeMethod_nv21CutterToNv12
(JNIEnv *env, jobject job, jbyteArray src, jbyteArray dst, jint cw, jint ch, jint w,
jint h, jbyteArray y,
jbyteArray u, jbyteArray v) {
uint8_t *srcArray = (uint8_t *) env->GetByteArrayElements(src, 0);
uint8_t *dstArray = (uint8_t *) env->GetByteArrayElements(dst, 0);
uint8_t *yArray = (uint8_t *) env->GetByteArrayElements(y, NULL);
uint8_t *uArray = (uint8_t *) env->GetByteArrayElements(u, NULL);
uint8_t *vArray = (uint8_t *) env->GetByteArrayElements(v, NULL);
jbyteArray transitJbyteArray = env->NewByteArray(w * h * 3 / 2);
uint8_t *transitArray = (uint8_t *) env->GetByteArrayElements(transitJbyteArray, 0);
jint ySize = w * h;
jint startx = (w - cw) / 2;
jint starty = (h - ch) / 2;
jint uvSize = (w >> 1) * (h >> 1);
uint8_t *y_src = srcArray;
uint8_t *uv_src = srcArray + ySize;
uint8_t *y_transit = transitArray;
uint8_t *u_transit = transitArray + ySize;
uint8_t *v_transit = transitArray + ySize + uvSize;
uint8_t *y_dst = dstArray;
uint8_t *uv_dst = dstArray + (cw * ch);
libyuv::NV21ToI420(y_src, w, uv_src, w, y_transit, w, u_transit, w >> 1, v_transit, w >> 1, w,
h);
libyuv::ConvertToI420(transitArray, ySize + uvSize, yArray, cw, uArray, cw >> 1,
vArray, cw >> 1,
startx, starty, w, h, cw, ch, libyuv::kRotate0, libyuv::FOURCC_I420);
libyuv::I420ToNV12(yArray, cw, uArray, cw >> 1, vArray, cw >> 1, y_dst, cw,
uv_dst, cw, cw, ch);
releaseByteArray(env, transitJbyteArray, transitArray, 0);
releaseByteArray(env, src, srcArray, 0);
releaseByteArray(env, dst, dstArray, 0);
releaseByteArray(env, y, yArray, 0);
releaseByteArray(env, v, vArray, 0);
releaseByteArray(env, u, uArray, 0);
} ;
#ifdef __cplusplus
}
#endif
#endif
以上就是jni层全部的代码基本上只涉及到数据转换和libyuv库的调用没啥太不好理解的地方。里面有注释旋转的代码有兴趣或者需求的童鞋可以恢复过来玩一玩。
这是yuv jni的目录。
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