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Add documentation to some avcodec.h's pix_fmt related functions and defines.

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Originally committed as revision 8171 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Panagiotis Issaris 2007-03-01 15:27:26 +00:00
parent b72ad0427e
commit 81299d421b
1 changed files with 41 additions and 8 deletions
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49
libavcodec/avcodec.h
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@ -2496,21 +2496,54 @@ void avcodec_set_dimensions(AVCodecContext *s, int width, int height);
enum PixelFormat avcodec_get_pix_fmt(const char* name);
unsigned int avcodec_pix_fmt_to_codec_tag(enum PixelFormat p);
#define FF_LOSS_RESOLUTION 0x0001 /* loss due to resolution change */
#define FF_LOSS_DEPTH 0x0002 /* loss due to color depth change */
#define FF_LOSS_COLORSPACE 0x0004 /* loss due to color space conversion */
#define FF_LOSS_ALPHA 0x0008 /* loss of alpha bits */
#define FF_LOSS_COLORQUANT 0x0010 /* loss due to color quantization */
#define FF_LOSS_CHROMA 0x0020 /* loss of chroma (e.g. rgb to gray conversion) */
#define FF_LOSS_RESOLUTION 0x0001 /**< loss due to resolution change */
#define FF_LOSS_DEPTH 0x0002 /**< loss due to color depth change */
#define FF_LOSS_COLORSPACE 0x0004 /**< loss due to color space conversion */
#define FF_LOSS_ALPHA 0x0008 /**< loss of alpha bits */
#define FF_LOSS_COLORQUANT 0x0010 /**< loss due to color quantization */
#define FF_LOSS_CHROMA 0x0020 /**< loss of chroma (e.g. RGB to gray conversion) */
/**
* compute the loss when converting from a pixel format to another
* Computes what kind of losses will occur when converting from one specific
* pixel format to another.
* When converting from one pixel format to another, information loss may occur.
* For example, when converting from RGB24 to GRAY, the color information will
* be lost. Similarly, other losses occur when converting from some formats to
* other formats. These losses can involve loss of chroma, but also loss of
* resolution, loss of color depth, loss due to the color space conversion, loss
* of the alpha bits or loss due to color quantization.
* avcodec_get_fix_fmt_loss() informs you on the various types of losses which
* will occur when converting from one pixel format to another.
*
* @param[in] dst_pix_fmt Destination pixel format.
* @param[in] src_pix_fmt Source pixel format.
* @param[in] has_alpha Whether the source pixel format alpha channel is used.
* @return Combination of flags informing you what kind of losses will occur.
*/
int avcodec_get_pix_fmt_loss(int dst_pix_fmt, int src_pix_fmt,
int has_alpha);
/**
* find best pixel format to convert to. Return -1 if none found
* Finds the best pixel format to convert to given a certain source pixel
* format. When converting from one pixel format to another, information loss
* may occur. For example, when converting from RGB24 to GRAY, the color
* information will be lost. Similarly, other losses occur when converting from
* some formats to other formats. avcodec_find_best_pix_fmt() searches which of
* the given pixel formats should be used to undergo the least amount of losses.
* The pixel formats from which it choses one, are determined by the
* \p pix_fmt_mask parameter.
*
* @code
* src_pix_fmt = PIX_FMT_YUV420P;
* pix_fmt_mask = (1 << PIX_FMT_YUV422P) || (1 << PIX_FMT_RGB24);
* dst_pix_fmt = avcodec_find_best_pix_fmt(pix_fmt_mask, src_pix_fmt, alpha, &loss);
* @endcode
*
* @param[in] pix_fmt_mask Bitmask determining which pixel format to choose from.
* @param[in] src_pix_fmt Source pixel format.
* @param[in] has_alpha Whether the source pixel format alpha channel is used.
* @param[out] loss_ptr Combination of flags informing you what kind of losses will occur.
* @return The best pixel format to convert to or -1 if none was found.
*/
int avcodec_find_best_pix_fmt(int pix_fmt_mask, int src_pix_fmt,
int has_alpha, int *loss_ptr);