YUV格式學習:NV12和YUV420P格式互換
阿新 • • 發佈:2019-02-07
NV12和YUV420的轉換是在相同取樣空間的轉換,只是個別分量位置的調整,只要明白了Y、U、V分量的佈置,就很容易寫出來。
程式碼如下:
/** yyyy yyyy uv uv -> yyyy yyyy uu vv */ void yuv420sp_to_yuv420p(unsigned char* yuv420sp, unsigned char* yuv420p, int width, int height) { int i, j; int y_size = width * height; unsigned char* y = yuv420sp; unsigned char* uv = yuv420sp + y_size; unsigned char* y_tmp = yuv420p; unsigned char* u_tmp = yuv420p + y_size; unsigned char* v_tmp = yuv420p + y_size * 5 / 4; // y memcpy(y_tmp, y, y_size); // u for (j = 0, i = 0; j < y_size/2; j+=2, i++) { u_tmp[i] = uv[j]; v_tmp[i] = uv[j+1]; } } /** yyyy yyyy uu vv -> yyyy yyyy uv uv */ void yuv420p_to_yuv420sp(unsigned char* yuv420p, unsigned char* yuv420sp, int width, int height) { int i, j; int y_size = width * height; unsigned char* y = yuv420p; unsigned char* u = yuv420p + y_size; unsigned char* v = yuv420p + y_size * 5 / 4; unsigned char* y_tmp = yuv420sp; unsigned char* uv_tmp = yuv420sp + y_size; // y memcpy(y_tmp, y, y_size); // u for (j = 0, i = 0; j < y_size/2; j+=2, i++) { // 此處可調整U、V的位置,變成NV12或NV21 #if 01 uv_tmp[j] = u[i]; uv_tmp[j+1] = v[i]; #else uv_tmp[j] = v[i]; uv_tmp[j+1] = u[i]; #endif } }
後記:
一口氣把自己研究很久的東西寫出來,好像都沒寫到點子上。以前也嘗試過寫技術性很強的文章,到處找資料,找出處,但後來發覺自己不是那塊料,於是就直接貼程式碼,理論的東西反而不說——因為說不清,也怕說錯。
關於YUV,初步聽說是在6、7年前的大學,開始接觸是在4、5年前,而真正瞭解其原理,卻是近些年。學習進度不可謂不慢。寫出來,也算有個交待。也為自己準備實現的YUV播放器做些準備。
遲 2015.8.5 晚上