av_image_fill_arrays

av_image_fill_arrays是FFmpeg中用于填充图像数据指针数组的函数之一。在音视频处理领域，正确使用av_image_fill_arrays函数可以帮助我们有效地处理图像数据。

av_image_fill_arrays函数原型

/**
 * Setup the data pointers and linesizes based on the specified image
 * parameters and the provided array.
 *
 * The fields of the given image are filled in by using the src
 * address which points to the image data buffer. Depending on the
 * specified pixel format, one or multiple image data pointers and
 * line sizes will be set.  If a planar format is specified, several
 * pointers will be set pointing to the different picture planes and
 * the line sizes of the different planes will be stored in the
 * lines_sizes array. Call with src == NULL to get the required
 * size for the src buffer.
 *
 * To allocate the buffer and fill in the dst_data and dst_linesize in
 * one call, use av_image_alloc().
 *
 * @param dst_data      data pointers to be filled in
 * @param dst_linesize  linesizes for the image in dst_data to be filled in
 * @param src           buffer which will contain or contains the actual image data, can be NULL
 * @param pix_fmt       the pixel format of the image
 * @param width         the width of the image in pixels
 * @param height        the height of the image in pixels
 * @param align         the value used in src for linesize alignment
 * @return the size in bytes required for src, a negative error code
 * in case of failure
 */
int av_image_fill_arrays(uint8_t *dst_data[4], int dst_linesize[4],
                         const uint8_t *src,
                         enum AVPixelFormat pix_fmt, int width, int height, int align)
{
    int ret, i;

    ret = av_image_check_size(width, height, 0, NULL);
    if (ret < 0)
        return ret;

    ret = av_image_fill_linesizes(dst_linesize, pix_fmt, width);
    if (ret < 0)
        return ret;

    for (i = 0; i < 4; i++)
        dst_linesize[i] = FFALIGN(dst_linesize[i], align);

    return av_image_fill_pointers(dst_data, pix_fmt, height, (uint8_t *)src, dst_linesize);
}

• dst_data: 指向一个指针数组，用于存储图像数据的指针。
• dst_linesize: 存储每个图像数据指针的大小。
• src: 指向包含图像数据的缓冲区。
• pix_fmt: 图像像素格式。
• width: 图像宽度。
• height: 图像高度。
• align: 对齐方式。

如何正确使用av_image_fill_arrays函数

以下是一个简单的示例代码，演示如何正确使用av_image_fill_arrays函数：

#include <libavutil/imgutils.h>

void fill_image_data(uint8_t *dst_data[4], int dst_linesize[4], uint8_t *src, enum AVPixelFormat pix_fmt, int width, int height) {
    int ret = av_image_fill_arrays(dst_data, dst_linesize, src, pix_fmt, width, height, 1);
    if (ret < 0) {
        // 错误处理
        printf("Error filling image data arrays\n");
    }
}

int main() {
    int width = 1920;
    int height = 1080;
    enum AVPixelFormat pix_fmt = AV_PIX_FMT_YUV420P;
    uint8_t *src = (uint8_t *)av_malloc(av_image_get_buffer_size(pix_fmt, width, height, 1));
    uint8_t *dst_data[4];
    int dst_linesize[4];

    fill_image_data(dst_data, dst_linesize, src, pix_fmt, width, height);

    // 使用填充好的图像数据进行后续处理

    av_free(src);
    return 0;
}

在这个示例代码中，首先分配了一个足够大的缓冲区用于存储图像数据，然后调用fill_image_data函数来填充图像数据指针数组。最后使用填充好的图像数据进行后续的图像处理操作。