Question

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;
}

Answer 1

您可以尝试使用... //Get input and output length int input_size = env->GetArrayLength(yuvByteArray_); int y_size = src_width * src_height; 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 + y_size; i420_input_frame.v = i420_input_frame.u + y_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; ...而不是数组的完整大小的代码。

y_size

可能您的代码基于https://github.com/begeekmyfriend/yasea/blob/master/library/src/main/libenc/jni/libenc.cc，根据该代码，您必须使用ConvertDate = DateSerial(Year(DateValue(DueDate)), Month(DateValue(DueDate)), Day(DateValue(DueDate)))

Answer 2

框架的输入大小存在问题：

应该是：

keytool -importkeystore -destkeystore new.p12 -deststoretype pkcs12 -srckeystore original.pfx

例如，如果您的帧为6x4

香奈儿 y 尺寸：6 * 4 = 24

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

香奈儿你尺寸：3 * 2 = 6

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

香奈儿 v 尺寸：3 * 2 = 6

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

阵列尺寸= 6 * 4 + 3 * 2 + 3 * 2 = 36
但实际帧大小=通道 y 大小= 36 * 2/3 = 24

Answer 3

gmetax几乎是正确的。

您正在使用整个数组的大小，您应该使用Y组件的大小src_width * src_height。

gmetax的答案是错误的，因为他在定义输出框时已经y_size代替out_size。我相信，正确的代码片段如下所示：

//Get input and output length
int input_size = env->GetArrayLength(yuvByteArray_);
int y_size = src_width * src_height;
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 + y_size;
i420_input_frame.v = i420_input_frame.u + y_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;

Answer 4

您正在尝试将YUV422图像缩放为YUV420，难怪颜色全都搞砸了。首先，您需要弄清楚YUV输入缓冲区的确切格式。从YUV_422_888的文档来看，它看起来可能代表平面格式和交错格式（如果像素跨度不是1）。从您的结果看，您的源是平面的并且Y平面的处理是可以的，但是您的错误在于处理U和V平面。要正确扩展：

你必须弄清楚你的U和V平面是否是交错的平面。很可能它们也是平面的。
使用libyuv中的ScalePlane分别缩放U和V。也许如果您进入I420Scale，则会为个人调用ScalePlane 飞机。同样，但为U和V使用正确的\ n \ n“ 飞机（每个飞机比I420Scale预期的大两倍）。

一些提示如何判断您是否有平面或交错U和V：尝试跳过图像缩放并保存它，以确保获得正确的结果（与源相同））。然后尝试将U帧或V帧清零，看看你得到了什么。如果U和V是平面的并且您将U平面设置为零，则应该看到整个图片更改颜色。如果它们是交错的，你将获得一半的图像改变而另一个保持不变。同样，您可以检查有关飞机尺寸，线条和偏移的假设。一旦确定YUV格式和布局，如果输入是平面的，则可以缩放单个平面，或者如果首先有交错输入，则需要对平面进行解交织，然后进行缩放。

或者，你可以使用ffmpeg / libav中的libswscale并尝试不同的格式来找到正确的格式，然后使用libyuv。

Answer 5

绿色图像是由其中一个平面充满0引起的。这意味着其中一架飞机是空的。这是因为我从YUV NV21而不是YUV I420进行转换。来自Android相机框架的图像是I420 YUV。

我们需要将它们转换为YUV I420才能与Libyuv一起正常工作。之后，我们可以开始使用该库为您提供的多种操作。例如旋转，缩放等。

以下是缩放方法的外观：

JNIEXPORT jint JNICALL
Java_com_aa_project_images_yuv_myJNIcl_scaleI420(JNIEnv *env, jclass type,
                                                 jobject srcBufferY,
                                                 jobject srcBufferU,
                                                 jobject srcBufferV,
                                                 jint srcWidth, jint srcHeight,
                                                 jobject dstBufferY,
                                                 jobject dstBufferU,
                                                 jobject dstBufferV,
                                                 jint dstWidth, jint dstHeight,
                                                 jint filterMode) {

    const uint8_t *srcY = static_cast<uint8_t *>(env->GetDirectBufferAddress(srcBufferY));
    const uint8_t *srcU = static_cast<uint8_t *>(env->GetDirectBufferAddress(srcBufferU));
    const uint8_t *srcV = static_cast<uint8_t *>(env->GetDirectBufferAddress(srcBufferV));
    uint8_t *dstY = static_cast<uint8_t *>(env->GetDirectBufferAddress(dstBufferY));
    uint8_t *dstU = static_cast<uint8_t *>(env->GetDirectBufferAddress(dstBufferU));
    uint8_t *dstV = static_cast<uint8_t *>(env->GetDirectBufferAddress(dstBufferV));

    return libyuv::I420Scale(srcY, srcWidth,
                             srcU, srcWidth / 2,
                             srcV, srcWidth / 2,
                             srcWidth, srcHeight,
                             dstY, dstWidth,
                             dstU, dstWidth / 2,
                             dstV, dstWidth / 2,
                             dstWidth, dstHeight,
                             static_cast<libyuv::FilterMode>(filterMode));
}

Problems when scaling a YUV image using libyuv library

5 个答案: