Commit 463b81de authored by wm4's avatar wm4

imgutils: add function to clear an image to black

Black isn't always just memset(ptr, 0, size). Limited YUV in particular
requires relatively non-obvious values, and filling a frame with
repeating 0 bytes is disallowed in some contexts. With component sizes
larger than 8 or packed YUV, this can become relatively complicated. So
having a generic function for this seems helpful.

In order to handle the complex cases in a generic way without destroying
performance, this code attempts to compute a black pixel, and then uses
that value to clear the image data quickly by using a function like
memset.

Common cases like yuv410p10 or rgba can't be handled with a simple
memset, so there is some code to fill memory with 2/4/8 byte patterns.
For the remaining cases, a generic slow fallback is used.
Signed-off-by: 's avatarAnton Khirnov <anton@khirnov.net>

Merged from Libav commit 45df7adc.
parent caa12027
......@@ -15,6 +15,9 @@ libavutil: 2015-08-28
API changes, most recent first:
2017-08-08 - xxxxxxx - lavu 55.72.100 - imgutils.h
Add av_image_fill_black().
2017-08-08 - xxxxxxx - lavu 55.71.100 - frame.h
Add av_frame_apply_cropping().
......
......@@ -491,3 +491,170 @@ int av_image_copy_to_buffer(uint8_t *dst, int dst_size,
return size;
}
// Fill dst[0..dst_size] with the bytes in clear[0..clear_size]. The clear
// bytes are repeated until dst_size is reached. If dst_size is unaligned (i.e.
// dst_size%clear_size!=0), the remaining data will be filled with the beginning
// of the clear data only.
static void memset_bytes(uint8_t *dst, size_t dst_size, uint8_t *clear,
size_t clear_size)
{
size_t pos = 0;
int same = 1;
int i;
if (!clear_size)
return;
// Reduce to memset() if possible.
for (i = 0; i < clear_size; i++) {
if (clear[i] != clear[0]) {
same = 0;
break;
}
}
if (same)
clear_size = 1;
if (clear_size == 1) {
memset(dst, clear[0], dst_size);
dst_size = 0;
} else if (clear_size == 2) {
uint16_t val = AV_RN16(clear);
for (; dst_size >= 2; dst_size -= 2) {
AV_WN16(dst, val);
dst += 2;
}
} else if (clear_size == 4) {
uint32_t val = AV_RN32(clear);
for (; dst_size >= 4; dst_size -= 4) {
AV_WN32(dst, val);
dst += 4;
}
} else if (clear_size == 8) {
uint32_t val = AV_RN64(clear);
for (; dst_size >= 8; dst_size -= 8) {
AV_WN64(dst, val);
dst += 8;
}
}
for (; dst_size; dst_size--)
*dst++ = clear[pos++ % clear_size];
}
// Maximum size in bytes of a plane element (usually a pixel, or multiple pixels
// if it's a subsampled packed format).
#define MAX_BLOCK_SIZE 32
int av_image_fill_black(uint8_t *dst_data[4], const ptrdiff_t dst_linesize[4],
enum AVPixelFormat pix_fmt, enum AVColorRange range,
int width, int height)
{
const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
int nb_planes = av_pix_fmt_count_planes(pix_fmt);
// A pixel or a group of pixels on each plane, with a value that represents black.
// Consider e.g. AV_PIX_FMT_UYVY422 for non-trivial cases.
uint8_t clear_block[4][MAX_BLOCK_SIZE] = {0}; // clear padding with 0
int clear_block_size[4] = {0};
ptrdiff_t plane_line_bytes[4] = {0};
int rgb, limited;
int plane, c;
if (!desc || nb_planes < 1 || nb_planes > 4 || desc->flags & AV_PIX_FMT_FLAG_HWACCEL)
return AVERROR(EINVAL);
rgb = !!(desc->flags & AV_PIX_FMT_FLAG_RGB);
limited = !rgb && range != AVCOL_RANGE_JPEG;
if (desc->flags & AV_PIX_FMT_FLAG_BITSTREAM) {
ptrdiff_t bytewidth = av_image_get_linesize(pix_fmt, width, 0);
uint8_t *data;
int mono = pix_fmt == AV_PIX_FMT_MONOWHITE || pix_fmt == AV_PIX_FMT_MONOBLACK;
int fill = pix_fmt == AV_PIX_FMT_MONOWHITE ? 0xFF : 0;
if (nb_planes != 1 || !(rgb || mono) || bytewidth < 1)
return AVERROR(EINVAL);
if (!dst_data)
return 0;
data = dst_data[0];
// (Bitstream + alpha will be handled incorrectly - it'll remain transparent.)
for (;height > 0; height--) {
memset(data, fill, bytewidth);
data += dst_linesize[0];
}
return 0;
}
for (c = 0; c < desc->nb_components; c++) {
const AVComponentDescriptor comp = desc->comp[c];
// We try to operate on entire non-subsampled pixel groups (for
// AV_PIX_FMT_UYVY422 this would mean two consecutive pixels).
clear_block_size[comp.plane] = FFMAX(clear_block_size[comp.plane], comp.step);
if (clear_block_size[comp.plane] > MAX_BLOCK_SIZE)
return AVERROR(EINVAL);
}
// Create a byte array for clearing 1 pixel (sometimes several pixels).
for (c = 0; c < desc->nb_components; c++) {
const AVComponentDescriptor comp = desc->comp[c];
// (Multiple pixels happen e.g. with AV_PIX_FMT_UYVY422.)
int w = clear_block_size[comp.plane] / comp.step;
uint8_t *c_data[4];
const int c_linesize[4] = {0};
uint16_t src_array[MAX_BLOCK_SIZE];
uint16_t src = 0;
int x;
if (comp.depth > 16)
return AVERROR(EINVAL);
if (!rgb && comp.depth < 8)
return AVERROR(EINVAL);
if (w < 1)
return AVERROR(EINVAL);
if (c == 0 && limited) {
src = 16 << (comp.depth - 8);
} else if ((c == 1 || c == 2) && !rgb) {
src = 128 << (comp.depth - 8);
} else if (c == 3) {
// (Assume even limited YUV uses full range alpha.)
src = (1 << comp.depth) - 1;
}
for (x = 0; x < w; x++)
src_array[x] = src;
for (x = 0; x < 4; x++)
c_data[x] = &clear_block[x][0];
av_write_image_line(src_array, c_data, c_linesize, desc, 0, 0, c, w);
}
for (plane = 0; plane < nb_planes; plane++) {
plane_line_bytes[plane] = av_image_get_linesize(pix_fmt, width, plane);
if (plane_line_bytes[plane] < 0)
return AVERROR(EINVAL);
}
if (!dst_data)
return 0;
for (plane = 0; plane < nb_planes; plane++) {
size_t bytewidth = plane_line_bytes[plane];
uint8_t *data = dst_data[plane];
int chroma_div = plane == 1 || plane == 2 ? desc->log2_chroma_h : 0;
int plane_h = ((height + ( 1 << chroma_div) - 1)) >> chroma_div;
for (; plane_h > 0; plane_h--) {
memset_bytes(data, bytewidth, &clear_block[plane][0], clear_block_size[plane]);
data += dst_linesize[plane];
}
}
return 0;
}
......@@ -238,6 +238,33 @@ int av_image_check_size2(unsigned int w, unsigned int h, int64_t max_pixels, enu
*/
int av_image_check_sar(unsigned int w, unsigned int h, AVRational sar);
/**
* Overwrite the image data with black. This is suitable for filling a
* sub-rectangle of an image, meaning the padding between the right most pixel
* and the left most pixel on the next line will not be overwritten. For some
* formats, the image size might be rounded up due to inherent alignment.
*
* If the pixel format has alpha, the alpha is cleared to opaque.
*
* This can return an error if the pixel format is not supported. Normally, all
* non-hwaccel pixel formats should be supported.
*
* Passing NULL for dst_data is allowed. Then the function returns whether the
* operation would have succeeded. (It can return an error if the pix_fmt is
* not supported.)
*
* @param dst_data data pointers to destination image
* @param dst_linesize linesizes for the destination image
* @param pix_fmt the pixel format of the image
* @param range the color range of the image (important for colorspaces such as YUV)
* @param width the width of the image in pixels
* @param height the height of the image in pixels
* @return 0 if the image data was cleared, a negative AVERROR code otherwise
*/
int av_image_fill_black(uint8_t *dst_data[4], const ptrdiff_t dst_linesize[4],
enum AVPixelFormat pix_fmt, enum AVColorRange range,
int width, int height);
/**
* @}
*/
......
......@@ -80,7 +80,7 @@
#define LIBAVUTIL_VERSION_MAJOR 55
#define LIBAVUTIL_VERSION_MINOR 71
#define LIBAVUTIL_VERSION_MINOR 72
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
......
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