使用libyuv库缩放YUV图像时出现的问题 [英] Problems when scaling a YUV image using libyuv library

问题描述

我正在开发基于 Camera API 2 的相机应用程序，我发现使用

我执行缩放后得到的结果：

我认为我在步幅方面做错了，或者提供了无效的YUV格式（也许我必须将图像转换为另一种格式？）。但是，我无法弄清楚错误在哪里，因为我不知道如何将绿色与缩放算法相关联。

这是转换代码I在使用时，你可以忽略返回NULL，因为还有与问题无关的进一步处理。

  #include< jni.h> 
 #include< stdint.h> 
 #include< android / log.h> 
 #include< inc / libyuv / scale.h> 
 #include< inc / libyuv.h> 
 #include< stdio.h> 
 
 
 #define LOG_TAGlibyuv-jni
 
 #define unused（x）UNUSED_ ## x __attribute __（（__ unused__））
 #define LOGD（...）__ android_log_print（ANDROID_LOG_DEBUG，LOG_TAG，__ VA_ARGS__）
 #define LOGE（...）__ android_log_print（ANDROID_LOG_ERROR，LOG_TAG，__ VA_ARGS_）
 
 struct YuvFrame {
 int宽度; 
 int height; 
 uint8_t * data; 
 uint8_t * y; 
 uint8_t * u; 
 uint8_t * v; 
}; 
 
 static struct YuvFrame i420_input_frame; 
 static struct YuvFrame i420_output_frame; 
 
 externC{
 
 JNIEXPORT jbyteArray JNICALL 
 Java_com_android_camera3_camera_hardware_session_output_photo_yuv_YuvJniInterface_scale420YuvByteArray（
 JNIEnv * env，jclass / * clazz * /，jbyteArray yuvByteArray_，jint src_width ，jint src_height，
 jint out_width，jint out_height）{
 
 jbyte * yuvByteArray = env-> GetByteArrayElements（yuvByteArray_，NULL）; 
 
 //获取输入和输出长度
 int input_size = env-> GetArrayLength（yuvByteArray_）; 
 int out_size = out_height * out_width; 
 
 //生成输入框
 i420_input_frame.width = src_width; 
 i420_input_frame.height = src_height; 
 i420_input_frame.data =（uint8_t *）yuvByteArray; 
 i420_input_frame.y = i420_input_frame.data; 
 i420_input_frame.u = i420_input_frame.y + input_size; 
 i420_input_frame.v = i420_input_frame.u + input_size / 4; 
 
 //生成输出框$​​ b $ b free（i420_output_frame.data）; 
 i420_output_frame.width = out_width; 
 i420_output_frame.height = out_height; 
 i420_output_frame.data = new unsigned char [out_size * 3/2]; 
 i420_output_frame.y = i420_output_frame.data; 
 i420_output_frame.u = i420_output_frame.y + out_size; 
 i420_output_frame.v = i420_output_frame.u + out_size / 4; 
 libyuv :: FilterMode mode = libyuv :: FilterModeEnum :: kFilterBilinear; 
 
 int result = I420Scale（i420_input_frame.y，i420_input_frame.width，
 i420_input_frame.u，i420_input_frame.width / 2，
 i420_input_frame.v，i420_input_frame.width / 2，
 i420_input_frame.width，i420_input_frame.height，
 i420_output_frame.y，i420_output_frame.width，
 i420_output_frame.u，i420_output_frame.width / 2，
 i420_output_frame.v，i420_output_frame.width / 2 ，
 i420_output_frame.width，i420_output_frame.height，
 mode）; 
 LOGD（图像结果％d，结果）; 
 env-> ReleaseByteArrayElements（yuvByteArray_，yuvByteArray，0）; 
返回NULL; 
} 
  

解决方案

你有一个问题框架的输入大小：

它应该是：

  int input_array_size = env-> GetArrayLength（yuvByteArray_）; 
 int input_size = input_array_size * 2/3; //这是帧大小
  

例如，如果你有一个6x4的帧

香奈儿 y 尺寸：6 * 4 = 24

  1 2 3 4 5 6 
 _ _ _ _ _ _ 
 | _ | _ | _ | _ | _ | _ | 1 
 | _ | _ | _ | _ | _ | _ | 2 
 | _ | _ | _ | _ | _ | _ | 3 
 | _ | _ | _ | _ | _ | _ | 4 
  

香奈儿你尺寸：3 * 2 = 6

  1 2 3 
 _ _ _ _ _ _ 
 | | | | 
 | _ _ | _ _ | _ _ | 1 
 | | | | 
 | _ _ | _ _ | _ _ | 2 
  

香奈儿 v 尺寸：3 * 2 = 6

  1 2 3 
 _ _ _ _ _ _ 
 | | | | 
 | _ _ | _ _ | _ _ | 1 
 | | | | 
 | _ _ | _ _ | _ _ | 2 
  

数组大小= 6 * 4 + 3 * 2 + 3 * 2 = 36

但实际帧大小=频道 y 大小= 36 * 2/3 = 24

I'm developing a camera app based on Camera API 2 and I have found several problems using the libyuv. I want to convert YUV_420_888 images retrieved from a ImageReader, but I'm having some problems with scaling in a reprocessable surface.

In essence: Images come out with tones of green instead of having the corresponding tones (I'm exporting the .yuv files and checking them using http://rawpixels.net/).

You can see an input example here:

And what I get after I perform scaling:

I think I am doing something wrong with strides, or providing an invalid YUV format (maybe I have to transform the image to another format?). However, I can't figure out where is the error since I don't know how to correlate the green color to the scaling algorithm.

This is the conversion code I am using, you can ignore the return NULL as there is further processing that is not related to the problem.

#include <jni.h>
#include <stdint.h>
#include <android/log.h>
#include <inc/libyuv/scale.h>
#include <inc/libyuv.h>
#include <stdio.h>


#define  LOG_TAG    "libyuv-jni"

#define unused(x) UNUSED_ ## x __attribute__((__unused__))
#define  LOGD(...)  __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)
#define  LOGE(...)  __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS_)

struct YuvFrame {
    int width;
    int height;
    uint8_t *data;
    uint8_t *y;
    uint8_t *u;
    uint8_t *v;
};

static struct YuvFrame i420_input_frame;
static struct YuvFrame i420_output_frame;

extern "C" {

JNIEXPORT jbyteArray JNICALL
Java_com_android_camera3_camera_hardware_session_output_photo_yuv_YuvJniInterface_scale420YuvByteArray(
        JNIEnv *env, jclass /*clazz*/, jbyteArray yuvByteArray_, jint src_width, jint src_height,
        jint out_width, jint out_height) {

    jbyte *yuvByteArray = env->GetByteArrayElements(yuvByteArray_, NULL);

    //Get input and output length
    int input_size = env->GetArrayLength(yuvByteArray_);
    int out_size = out_height * out_width;

    //Generate input frame
    i420_input_frame.width = src_width;
    i420_input_frame.height = src_height;
    i420_input_frame.data = (uint8_t *) yuvByteArray;
    i420_input_frame.y = i420_input_frame.data;
    i420_input_frame.u = i420_input_frame.y + input_size;
    i420_input_frame.v = i420_input_frame.u + input_size / 4;

    //Generate output frame
    free(i420_output_frame.data);
    i420_output_frame.width = out_width;
    i420_output_frame.height = out_height;
    i420_output_frame.data = new unsigned char[out_size * 3 / 2];
    i420_output_frame.y = i420_output_frame.data;
    i420_output_frame.u = i420_output_frame.y + out_size;
    i420_output_frame.v = i420_output_frame.u + out_size / 4;
    libyuv::FilterMode mode = libyuv::FilterModeEnum::kFilterBilinear;

    int result = I420Scale(i420_input_frame.y, i420_input_frame.width,
                           i420_input_frame.u, i420_input_frame.width / 2,
                           i420_input_frame.v, i420_input_frame.width / 2,
                           i420_input_frame.width, i420_input_frame.height,
                           i420_output_frame.y, i420_output_frame.width,
                           i420_output_frame.u, i420_output_frame.width / 2,
                           i420_output_frame.v, i420_output_frame.width / 2,
                           i420_output_frame.width, i420_output_frame.height,
                           mode);
    LOGD("Image result %d", result);
    env->ReleaseByteArrayElements(yuvByteArray_, yuvByteArray, 0);
    return NULL;
}

解决方案

You have an issue with the input size of the frame:

It should be:

int input_array_size = env->GetArrayLength(yuvByteArray_);
int input_size = input_array_size * 2 / 3; //This is the frame size

For example, If you have a Frame that is 6x4

Chanel y size: 6*4 = 24

 1 2 3 4 5 6
 _ _ _ _ _ _
|_|_|_|_|_|_| 1
|_|_|_|_|_|_| 2
|_|_|_|_|_|_| 3
|_|_|_|_|_|_| 4

Chanel u size: 3*2 = 6

  1   2   3 
 _ _ _ _ _ _
|   |   |   | 
|_ _|_ _|_ _| 1
|   |   |   | 
|_ _|_ _|_ _| 2

Chanel v size: 3*2 = 6

  1   2   3 
 _ _ _ _ _ _
|   |   |   | 
|_ _|_ _|_ _| 1
|   |   |   | 
|_ _|_ _|_ _| 2

Array Size = 6*4+3*2+3*2 = 36
But actual Frame Size = channel y Size = 36 * 2 / 3 = 24

这篇关于使用libyuv库缩放YUV图像时出现的问题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！