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android4.0 USB Camera实例(五补充)jpg压缩
前一篇最后 我们说了一个直接将yuv转成jpg的函数 但是转换没有成功 原函数是yuv420转jpg的 研究了下发现
yuv420隔行扫描的的序列是这样的
YYYY
YYYY
UVUV
而yuv422的隔行扫描的序列是这样的
YU YV YU YV YU YV
所以将函数作如下修改
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; }即可将yuv422直接转化成jpg
接口函数修改如下
JNIEXPORT jint JNICALL Java_com_hclydao_usbcamera_Fimcgzsd_writefile(JNIEnv * env, jclass obj,jbyteArray yuvdata,jbyteArray filename)//jintArray rgbdata { jbyte *ydata = http://www.mamicode.com/(jbyte*)(*env)->GetByteArrayElements(env, yuvdata, 0);>还是要静下心来研究
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