pixdesc.h 8.9 KB

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  1. /*
  2. * pixel format descriptor
  3. * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at>
  4. *
  5. * This file is part of FFmpeg.
  6. *
  7. * FFmpeg is free software; you can redistribute it and/or
  8. * modify it under the terms of the GNU Lesser General Public
  9. * License as published by the Free Software Foundation; either
  10. * version 2.1 of the License, or (at your option) any later version.
  11. *
  12. * FFmpeg is distributed in the hope that it will be useful,
  13. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15. * Lesser General Public License for more details.
  16. *
  17. * You should have received a copy of the GNU Lesser General Public
  18. * License along with FFmpeg; if not, write to the Free Software
  19. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20. */
  21. #ifndef AVUTIL_PIXDESC_H
  22. #define AVUTIL_PIXDESC_H
  23. #include <inttypes.h>
  24. #include "pixfmt.h"
  25. typedef struct AVComponentDescriptor {
  26. uint16_t plane :2; ///< which of the 4 planes contains the component
  27. /**
  28. * Number of elements between 2 horizontally consecutive pixels minus 1.
  29. * Elements are bits for bitstream formats, bytes otherwise.
  30. */
  31. uint16_t step_minus1 :3;
  32. /**
  33. * Number of elements before the component of the first pixel plus 1.
  34. * Elements are bits for bitstream formats, bytes otherwise.
  35. */
  36. uint16_t offset_plus1 :3;
  37. uint16_t shift :3; ///< number of least significant bits that must be shifted away to get the value
  38. uint16_t depth_minus1 :4; ///< number of bits in the component minus 1
  39. } AVComponentDescriptor;
  40. /**
  41. * Descriptor that unambiguously describes how the bits of a pixel are
  42. * stored in the up to 4 data planes of an image. It also stores the
  43. * subsampling factors and number of components.
  44. *
  45. * @note This is separate of the colorspace (RGB, YCbCr, YPbPr, JPEG-style YUV
  46. * and all the YUV variants) AVPixFmtDescriptor just stores how values
  47. * are stored not what these values represent.
  48. */
  49. typedef struct AVPixFmtDescriptor {
  50. const char *name;
  51. uint8_t nb_components; ///< The number of components each pixel has, (1-4)
  52. /**
  53. * Amount to shift the luma width right to find the chroma width.
  54. * For YV12 this is 1 for example.
  55. * chroma_width = -((-luma_width) >> log2_chroma_w)
  56. * The note above is needed to ensure rounding up.
  57. * This value only refers to the chroma components.
  58. */
  59. uint8_t log2_chroma_w; ///< chroma_width = -((-luma_width )>>log2_chroma_w)
  60. /**
  61. * Amount to shift the luma height right to find the chroma height.
  62. * For YV12 this is 1 for example.
  63. * chroma_height= -((-luma_height) >> log2_chroma_h)
  64. * The note above is needed to ensure rounding up.
  65. * This value only refers to the chroma components.
  66. */
  67. uint8_t log2_chroma_h;
  68. uint8_t flags;
  69. /**
  70. * Parameters that describe how pixels are packed.
  71. * If the format has 2 or 4 components, then alpha is last.
  72. * If the format has 1 or 2 components, then luma is 0.
  73. * If the format has 3 or 4 components,
  74. * if the RGB flag is set then 0 is red, 1 is green and 2 is blue;
  75. * otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V.
  76. */
  77. AVComponentDescriptor comp[4];
  78. } AVPixFmtDescriptor;
  79. #define PIX_FMT_BE 1 ///< Pixel format is big-endian.
  80. #define PIX_FMT_PAL 2 ///< Pixel format has a palette in data[1], values are indexes in this palette.
  81. #define PIX_FMT_BITSTREAM 4 ///< All values of a component are bit-wise packed end to end.
  82. #define PIX_FMT_HWACCEL 8 ///< Pixel format is an HW accelerated format.
  83. #define PIX_FMT_PLANAR 16 ///< At least one pixel component is not in the first data plane
  84. #define PIX_FMT_RGB 32 ///< The pixel format contains RGB-like data (as opposed to YUV/grayscale)
  85. /**
  86. * The pixel format is "pseudo-paletted". This means that FFmpeg treats it as
  87. * paletted internally, but the palette is generated by the decoder and is not
  88. * stored in the file.
  89. */
  90. #define PIX_FMT_PSEUDOPAL 64
  91. #define PIX_FMT_ALPHA 128 ///< The pixel format has an alpha channel
  92. #if FF_API_PIX_FMT_DESC
  93. /**
  94. * The array of all the pixel format descriptors.
  95. */
  96. extern const AVPixFmtDescriptor av_pix_fmt_descriptors[];
  97. #endif
  98. /**
  99. * Read a line from an image, and write the values of the
  100. * pixel format component c to dst.
  101. *
  102. * @param data the array containing the pointers to the planes of the image
  103. * @param linesize the array containing the linesizes of the image
  104. * @param desc the pixel format descriptor for the image
  105. * @param x the horizontal coordinate of the first pixel to read
  106. * @param y the vertical coordinate of the first pixel to read
  107. * @param w the width of the line to read, that is the number of
  108. * values to write to dst
  109. * @param read_pal_component if not zero and the format is a paletted
  110. * format writes the values corresponding to the palette
  111. * component c in data[1] to dst, rather than the palette indexes in
  112. * data[0]. The behavior is undefined if the format is not paletted.
  113. */
  114. void av_read_image_line(uint16_t *dst, const uint8_t *data[4], const int linesize[4],
  115. const AVPixFmtDescriptor *desc, int x, int y, int c, int w, int read_pal_component);
  116. /**
  117. * Write the values from src to the pixel format component c of an
  118. * image line.
  119. *
  120. * @param src array containing the values to write
  121. * @param data the array containing the pointers to the planes of the
  122. * image to write into. It is supposed to be zeroed.
  123. * @param linesize the array containing the linesizes of the image
  124. * @param desc the pixel format descriptor for the image
  125. * @param x the horizontal coordinate of the first pixel to write
  126. * @param y the vertical coordinate of the first pixel to write
  127. * @param w the width of the line to write, that is the number of
  128. * values to write to the image line
  129. */
  130. void av_write_image_line(const uint16_t *src, uint8_t *data[4], const int linesize[4],
  131. const AVPixFmtDescriptor *desc, int x, int y, int c, int w);
  132. /**
  133. * Return the pixel format corresponding to name.
  134. *
  135. * If there is no pixel format with name name, then looks for a
  136. * pixel format with the name corresponding to the native endian
  137. * format of name.
  138. * For example in a little-endian system, first looks for "gray16",
  139. * then for "gray16le".
  140. *
  141. * Finally if no pixel format has been found, returns AV_PIX_FMT_NONE.
  142. */
  143. enum AVPixelFormat av_get_pix_fmt(const char *name);
  144. /**
  145. * Return the short name for a pixel format, NULL in case pix_fmt is
  146. * unknown.
  147. *
  148. * @see av_get_pix_fmt(), av_get_pix_fmt_string()
  149. */
  150. const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt);
  151. /**
  152. * Print in buf the string corresponding to the pixel format with
  153. * number pix_fmt, or an header if pix_fmt is negative.
  154. *
  155. * @param buf the buffer where to write the string
  156. * @param buf_size the size of buf
  157. * @param pix_fmt the number of the pixel format to print the
  158. * corresponding info string, or a negative value to print the
  159. * corresponding header.
  160. */
  161. char *av_get_pix_fmt_string (char *buf, int buf_size, enum AVPixelFormat pix_fmt);
  162. /**
  163. * Return the number of bits per pixel used by the pixel format
  164. * described by pixdesc.
  165. *
  166. * The returned number of bits refers to the number of bits actually
  167. * used for storing the pixel information, that is padding bits are
  168. * not counted.
  169. */
  170. int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
  171. /**
  172. * Return the number of bits per pixel for the pixel format
  173. * described by pixdesc, including any padding or unused bits.
  174. */
  175. int av_get_padded_bits_per_pixel(const AVPixFmtDescriptor *pixdesc);
  176. /**
  177. * @return a pixel format descriptor for provided pixel format or NULL if
  178. * this pixel format is unknown.
  179. */
  180. const AVPixFmtDescriptor *av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt);
  181. /**
  182. * Iterate over all pixel format descriptors known to libavutil.
  183. *
  184. * @param prev previous descriptor. NULL to get the first descriptor.
  185. *
  186. * @return next descriptor or NULL after the last descriptor
  187. */
  188. const AVPixFmtDescriptor *av_pix_fmt_desc_next(const AVPixFmtDescriptor *prev);
  189. /**
  190. * @return an AVPixelFormat id described by desc, or AV_PIX_FMT_NONE if desc
  191. * is not a valid pointer to a pixel format descriptor.
  192. */
  193. enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc);
  194. /**
  195. * Utility function to access log2_chroma_w log2_chroma_h from
  196. * the pixel format AVPixFmtDescriptor.
  197. *
  198. * See avcodec_get_chroma_sub_sample() for a function that asserts a
  199. * valid pixel format instead of returning an error code.
  200. * Its recommanded that you use avcodec_get_chroma_sub_sample unless
  201. * you do check the return code!
  202. *
  203. * @param[in] pix_fmt the pixel format
  204. * @param[out] h_shift store log2_chroma_h
  205. * @param[out] v_shift store log2_chroma_w
  206. *
  207. * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format
  208. */
  209. int av_pix_fmt_get_chroma_sub_sample(enum AVPixelFormat pix_fmt,
  210. int *h_shift, int *v_shift);
  211. #endif /* AVUTIL_PIXDESC_H */