Move pixdesc.{h,c} from libavcodec to libavutil.

This way pixdescs can be used without requiring a dependency on
libavcodec.

Originally committed as revision 20389 to svn://svn.ffmpeg.org/ffmpeg/trunk

1 files changed, 207 insertions, 0 deletions

diff --git a/libavutil/pixdesc.h b/libavutil/pixdesc.h
new file mode 100644
index 0000000000..fd1428fd81
--- /dev/null
+++ b/libavutil/pixdesc.h
@@ -0,0 +1,207 @@
+/*
+ * pixel format descriptor
+ * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_PIXDESC_H
+#define AVUTIL_PIXDESC_H
+
+#include <inttypes.h>
+
+#include "intreadwrite.h"
+
+typedef struct AVComponentDescriptor{
+    uint16_t plane        :2;            ///< which of the 4 planes contains the component
+
+    /**
+     * Number of elements between 2 horizontally consecutive pixels minus 1.
+     * Elements are bits for bitstream formats, bytes otherwise.
+     */
+    uint16_t step_minus1  :3;
+
+    /**
+     * Number of elements before the component of the first pixel plus 1.
+     * Elements are bits for bitstream formats, bytes otherwise.
+     */
+    uint16_t offset_plus1 :3;
+    uint16_t shift        :3;            ///< number of least significant bits that must be shifted away to get the value
+    uint16_t depth_minus1 :4;            ///< number of bits in the component minus 1
+}AVComponentDescriptor;
+
+/**
+ * Descriptor that unambiguously describes how the bits of a pixel are
+ * stored in the up to 4 data planes of an image. It also stores the
+ * subsampling factors and number of components.
+ *
+ * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
+ *       and all the YUV variants) AVPixFmtDescriptor just stores how values
+ *       are stored not what these values represent.
+ */
+typedef struct AVPixFmtDescriptor{
+    const char *name;
+    uint8_t nb_channels;        ///< The number of components each pixel has, (1-4)
+
+    /**
+     * Amount to shift the luma width right to find the chroma width.
+     * For YV12 this is 1 for example.
+     * chroma_width = -((-luma_width) >> log2_chroma_w)
+     * The note above is needed to ensure rounding up.
+     */
+    uint8_t log2_chroma_w;      ///< chroma_width = -((-luma_width )>>log2_chroma_w)
+
+    /**
+     * Amount to shift the luma height right to find the chroma height.
+     * For YV12 this is 1 for example.
+     * chroma_height= -((-luma_height) >> log2_chroma_h)
+     * The note above is needed to ensure rounding up.
+     */
+    uint8_t log2_chroma_h;
+    uint8_t flags;
+    AVComponentDescriptor comp[4]; ///< parameters that describe how pixels are packed
+}AVPixFmtDescriptor;
+
+#define PIX_FMT_BE        1 ///< big-endian
+#define PIX_FMT_PAL       2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
+#define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
+#define PIX_FMT_HWACCEL   8 ///< Pixel format is an HW accelerated format.
+
+/**
+ * The array of all the pixel format descriptors.
+ */
+extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
+
+/**
+ * Reads a line from an image, and writes to dst the values of the
+ * pixel format component c.
+ *
+ * @param data the array containing the pointers to the planes of the image
+ * @param linesizes the array containing the linesizes of the image
+ * @param desc the pixel format descriptor for the image
+ * @param x the horizontal coordinate of the first pixel to read
+ * @param y the vertical coordinate of the first pixel to read
+ * @param w the width of the line to read, that is the number of
+ * values to write to dst
+ * @param read_pal_component if not zero and the format is a paletted
+ * format writes to dst the values corresponding to the palette
+ * component c in data[1], rather than the palette indexes in
+ * data[0]. The behavior is undefined if the format is not paletted.
+ */
+static inline void read_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
+                             const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component)
+{
+    AVComponentDescriptor comp= desc->comp[c];
+    int plane= comp.plane;
+    int depth= comp.depth_minus1+1;
+    int mask = (1<<depth)-1;
+    int shift= comp.shift;
+    int step = comp.step_minus1+1;
+    int flags= desc->flags;
+
+    if (flags & PIX_FMT_BITSTREAM){
+        int skip = x*step + comp.offset_plus1-1;
+        const uint8_t *p = data[plane] + y*linesize[plane] + (skip>>3);
+        int shift = 8 - depth - (skip&7);
+
+        while(w--){
+            int val = (*p >> shift) & mask;
+            if(read_pal_component)
+                val= data[1][4*val + c];
+            shift -= step;
+            p -= shift>>3;
+            shift &= 7;
+            *dst++= val;
+        }
+    } else {
+        const uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
+
+        while(w--){
+            int val;
+            if(flags & PIX_FMT_BE) val= AV_RB16(p);
+            else                   val= AV_RL16(p);
+            val = (val>>shift) & mask;
+            if(read_pal_component)
+                val= data[1][4*val + c];
+            p+= step;
+            *dst++= val;
+        }
+    }
+}
+
+/**
+ * Writes the values from src to the pixel format component c of an
+ * image line.
+ *
+ * @param src array containing the values to write
+ * @param data the array containing the pointers to the planes of the
+ * image to write into. It is supposed to be zeroed.
+ * @param linesizes the array containing the linesizes of the image
+ * @param desc the pixel format descriptor for the image
+ * @param x the horizontal coordinate of the first pixel to write
+ * @param y the vertical coordinate of the first pixel to write
+ * @param w the width of the line to write, that is the number of
+ * values to write to the image line
+ */
+static inline void write_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
+                              const AVPixFmtDescriptor *desc, int x, int y, int c, int w)
+{
+    AVComponentDescriptor comp = desc->comp[c];
+    int plane = comp.plane;
+    int depth = comp.depth_minus1+1;
+    int step  = comp.step_minus1+1;
+    int flags = desc->flags;
+
+    if (flags & PIX_FMT_BITSTREAM) {
+        int skip = x*step + comp.offset_plus1-1;
+        uint8_t *p = data[plane] + y*linesize[plane] + (skip>>3);
+        int shift = 8 - depth - (skip&7);
+
+        while (w--) {
+            *p |= *src++ << shift;
+            shift -= step;
+            p -= shift>>3;
+            shift &= 7;
+        }
+    } else {
+        int shift = comp.shift;
+        uint8_t *p = data[plane]+ y*linesize[plane] + x*step + comp.offset_plus1-1;
+
+        while (w--) {
+            if (flags & PIX_FMT_BE) {
+                uint16_t val = AV_RB16(p) | (*src++<<shift);
+                AV_WB16(p, val);
+            } else {
+                uint16_t val = AV_RL16(p) | (*src++<<shift);
+                AV_WL16(p, val);
+            }
+            p+= step;
+        }
+    }
+}
+
+/**
+ * Returns the number of bits per pixel used by the pixel format
+ * described by pixdesc.
+ *
+ * The returned number of bits refers to the number of bits actually
+ * used for storing the pixel information, that is padding bits are
+ * not counted.
+ */
+int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
+
+#endif /* AVUTIL_PIXDESC_H */