linux yuv420sp_to_jpg
时间: 2023-06-10 16:06:24 浏览: 64
在 Linux 系统中,可以使用 FFmpeg 工具将 YUV420SP 格式的视频帧转换为 JPEG 格式的图像。以下是一个示例命令:
```
ffmpeg -s 640x480 -pix_fmt yuv420p -i input.yuv -frames:v 1 output.jpg
```
其中,`-s` 参数指定视频帧的分辨率,`-pix_fmt` 参数指定 YUV420SP 格式,`-i` 参数指定输入文件名,`-frames:v` 参数指定要提取的帧数,`output.jpg` 是输出 JPEG 图像的文件名。
请注意,YUV420SP 格式的视频帧通常是没有头部信息的,因此需要提供视频帧的分辨率信息。另外,由于 YUV420SP 格式的数据中包含了亮度和色度信息,因此需要对数据进行处理才能将其转换为 RGB 格式的图像。这些处理步骤通常会在 FFmpeg 工具内部完成。
相关问题
yuv420sp_to_jpg C语言
下面是将yuv420sp格式的图像转换为jpeg格式的C语言代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <jpeglib.h>
void yuv420sp_to_jpg(unsigned char *yuv, int width, int height, char *filename) {
struct jpeg_compress_struct cinfo;
struct jpeg_error_mgr jerr;
JSAMPROW row_pointer[1];
int row_stride;
FILE *outfile = fopen(filename, "wb");
if (outfile == NULL) {
fprintf(stderr, "Cannot open output file %s\n", filename);
return;
}
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_compress(&cinfo);
jpeg_stdio_dest(&cinfo, outfile);
cinfo.image_width = width;
cinfo.image_height = height;
cinfo.input_components = 3;
cinfo.in_color_space = JCS_YCbCr;
jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, 90, TRUE);
jpeg_start_compress(&cinfo, TRUE);
row_stride = width * 3;
JSAMPLE *rgb = (JSAMPLE *)malloc(row_stride);
while (cinfo.next_scanline < cinfo.image_height) {
int y, u, v;
unsigned char *py, *pu, *pv;
py = yuv + cinfo.next_scanline * width;
pu = yuv + width * height + (cinfo.next_scanline >> 1) * width;
pv = yuv + width * height * 5 / 4 + (cinfo.next_scanline >> 1) * width;
for (int i = 0, j = 0; i < width; i += 2, j += 6) {
y = py[i];
u = pu[j] - 128;
v = pv[j] - 128;
rgb[i * 3] = (unsigned char)(y + 1.4075 * v);
rgb[i * 3 + 1] = (unsigned char)(y - 0.3455 * u - 0.7169 * v);
rgb[i * 3 + 2] = (unsigned char)(y + 1.779 * u);
y = py[i + 1];
rgb[(i + 1) * 3] = (unsigned char)(y + 1.4075 * v);
rgb[(i + 1) * 3 + 1] = (unsigned char)(y - 0.3455 * u - 0.7169 * v);
rgb[(i + 1) * 3 + 2] = (unsigned char)(y + 1.779 * u);
}
row_pointer[0] = rgb;
jpeg_write_scanlines(&cinfo, row_pointer, 1);
}
free(rgb);
jpeg_finish_compress(&cinfo);
fclose(outfile);
jpeg_destroy_compress(&cinfo);
}
```
其中,yuv是yuv420sp格式的图像数据,width和height分别是图像的宽和高,filename是要保存的jpeg文件名。该函数使用libjpeg库将yuv420sp格式的图像数据转换为jpeg格式的图像数据,并保存到指定的文件中。具体的转换过程是将yuv数据转换为rgb数据,然后使用libjpeg库进行压缩编码。
jpg to yuv420sp C语言
将JPEG格式的图片转换为YUV420SP格式,可以使用libjpeg库来读取JPEG图片,然后使用以下代码将RGB格式的图片转换为YUV420SP格式:
```c
#include <stdio.h>
#include <stdlib.h>
#include <jpeglib.h>
// Convert RGB to YUV420SP
void rgb2yuv(unsigned char *rgb, unsigned char *yuv, int width, int height)
{
int frameSize = width * height;
int yIndex = 0;
int uvIndex = frameSize;
int r, g, b, y, u, v;
for (int j = 0; j < height; j++) {
for (int i = 0; i < width; i++) {
r = rgb[j * width * 3 + i * 3];
g = rgb[j * width * 3 + i * 3 + 1];
b = rgb[j * width * 3 + i * 3 + 2];
y = ((66 * r + 129 * g + 25 * b + 128) >> 8) + 16;
u = ((-38 * r - 74 * g + 112 * b + 128) >> 8) + 128;
v = ((112 * r - 94 * g - 18 * b + 128) >> 8) + 128;
y = (y < 16) ? 16 : ((y > 255) ? 255 : y);
u = (u < 0) ? 0 : ((u > 255) ? 255 : u);
v = (v < 0) ? 0 : ((v > 255) ? 255 : v);
yuv[yIndex++] = (unsigned char)y;
if (j % 2 == 0 && i % 2 == 0) {
yuv[uvIndex++] = (unsigned char)u;
yuv[uvIndex++] = (unsigned char)v;
}
}
}
}
int main(int argc, char *argv[])
{
if (argc != 3) {
printf("Usage: %s input.jpg output.yuv\n", argv[0]);
return 0;
}
char *input_file = argv[1];
char *output_file = argv[2];
// Read JPEG image
FILE *file = fopen(input_file, "rb");
if (!file) {
printf("Error: Unable to open input file %s\n", input_file);
return 0;
}
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, file);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
int width = cinfo.output_width;
int height = cinfo.output_height;
int numChannels = cinfo.output_components;
int row_stride = width * numChannels;
unsigned char *rgb = (unsigned char *)malloc(width * height * numChannels);
unsigned char *yuv = (unsigned char *)malloc(width * height * 3 / 2);
JSAMPARRAY buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr)&cinfo, JPOOL_IMAGE, row_stride, 1);
int row = 0;
while (cinfo.output_scanline < cinfo.output_height) {
jpeg_read_scanlines(&cinfo, buffer, 1);
for (int i = 0; i < row_stride; i += numChannels) {
rgb[row * row_stride + i] = buffer[0][i];
rgb[row * row_stride + i + 1] = buffer[0][i + 1];
rgb[row * row_stride + i + 2] = buffer[0][i + 2];
}
row++;
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(file);
// Convert RGB to YUV420SP
rgb2yuv(rgb, yuv, width, height);
// Write YUV420SP image
file = fopen(output_file, "wb");
if (!file) {
printf("Error: Unable to open output file %s\n", output_file);
return 0;
}
fwrite(yuv, 1, width * height * 3 / 2, file);
fclose(file);
free(rgb);
free(yuv);
return 0;
}
```
在程序中,首先使用libjpeg库读取JPEG图片,然后将RGB格式的图片转换为YUV420SP格式,最后将YUV420SP格式的图片写入文件。注意,在YUV420SP格式中,Y分量占据前width * height个字节,U和V分量共占据(width * height) / 2个字节。