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
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