android4.0 USB Camera示例(五个辅助)jpg压缩

前的最后一个　我们说，一个直接yuv变成jpg该功能　但是转换不成功　主要功能是yuv420转jpg的　根据研究发现

yuv420的序列是这种

YYYY

YYYY

UVUV

而yuv422的隔行扫描的序列是这种

YU YV YU YV YU YV

所以将函数作例如以下改动

static int put_jpeg_yuv420p_memory(unsigned char *dest_image,
unsigned char *input_image, int width, int height)
{
int i, j, jpeg_image_size;

JSAMPROW y[16],cb[16],cr[16]; // y[2][5] = color sample of row 2 and pixel column 5; (one plane)
JSAMPARRAY data[3]; // t[0][2][5] = color sample 0 of row 2 and column 5

struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
char *pbuf = NULL;
int jpglen = 0;
data[0] = y;
data[1] = cb;
data[2] = cr;

cinfo.err = jpeg_std_error(&jerr);  // errors get written to stderr

jpeg_create_compress(&cinfo);
cinfo.image_width = width;
cinfo.image_height = height;
cinfo.input_components = 3;
jpeg_set_defaults (&cinfo);

jpeg_set_colorspace(&cinfo, JCS_YCbCr);

cinfo.raw_data_in = TRUE;                  // supply downsampled data
cinfo.do_fancy_downsampling = FALSE;       // fix segfaulst with v7
cinfo.comp_info[0].h_samp_factor = 2;
cinfo.comp_info[0].v_samp_factor = 2;
cinfo.comp_info[1].h_samp_factor = 1;
cinfo.comp_info[1].v_samp_factor = 1;
cinfo.comp_info[2].h_samp_factor = 1;
cinfo.comp_info[2].v_samp_factor = 1;

jpeg_set_quality(&cinfo, 80, TRUE);
cinfo.dct_method = JDCT_FASTEST;

jpeg_mem_dest(&cinfo, &pbuf, &jpglen);    // data written to mem

jpeg_start_compress (&cinfo, TRUE);

for (j = 0; j < height; j += 16) {
for (i = 0; i < 16; i++) {
y[i] = input_image + width * (i + j);
//cb[i/2] = input_image + width * height + width / 2 * ((i + j) / 2);
//cr[i/2] = input_image + width * height + width * height / 4 + width / 2 * ((i + j) / 2);
if (i%2 == 0)
cb[i/2] = input_image + width * ((i + j) / 2);
else
cr[i/2] = input_image + width * ((i + j) / 2);
}
jpeg_write_raw_data(&cinfo, data, 16);
}

jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
memcpy(dest_image,pbuf,jpglen);
if(pbuf)
free(pbuf);
return jpglen;
}

就可以将yuv422直接转化成jpg

接口函数改动例如以下

JNIEXPORT jint JNICALL Java_com_hclydao_usbcamera_Fimcgzsd_writefile(JNIEnv * env, jclass obj,jbyteArray yuvdata,jbyteArray filename)//jintArray rgbdata
{
jbyte *ydata = (jbyte*)(*env)->GetByteArrayElements(env, yuvdata, 0);
jbyte *filedir = (jbyte*)(*env)->GetByteArrayElements(env, filename, 0);

FILE * outfile;
if ((outfile = fopen(filedir, "wb")) == NULL) {
LOGE("++++++++++++open %s failed\n",filedir);
return -1;
}

unsigned char* dst = malloc(mwidth*mheight*3*sizeof(char));
int size = put_jpeg_yuv420p_memory(dst,ydata,mwidth,mheight);
fwrite(dst,size,1,outfile);
if(dst)free(dst);
if(jpgdata)free(jpgdata);
fclose(outfile);
(*env)->ReleaseByteArrayElements(env, yuvdata, ydata, 0);
(*env)->ReleaseByteArrayElements(env, filename, filedir, 0);
}

还是静下心来研究