diff options
Diffstat (limited to 'libavutil/pixdesc.h')
| -rw-r--r-- | libavutil/pixdesc.h | 109 |
1 files changed, 94 insertions, 15 deletions
diff --git a/libavutil/pixdesc.h b/libavutil/pixdesc.h index 23dc009a12..78f8d559c4 100644 --- a/libavutil/pixdesc.h +++ b/libavutil/pixdesc.h @@ -2,20 +2,20 @@ * pixel format descriptor * Copyright (c) 2009 Michael Niedermayer <michaelni@gmx.at> * - * This file is part of Libav. + * This file is part of FFmpeg. * - * Libav is free software; you can redistribute it and/or + * 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. * - * Libav is distributed in the hope that it will be useful, + * 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 Libav; if not, write to the Free Software + * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ @@ -90,9 +90,12 @@ typedef struct AVPixFmtDescriptor { uint8_t flags; /** - * Parameters that describe how pixels are packed. If the format - * has chroma components, they must be stored in comp[1] and - * comp[2]. + * Parameters that describe how pixels are packed. + * If the format has 2 or 4 components, then alpha is last. + * If the format has 1 or 2 components, then luma is 0. + * If the format has 3 or 4 components: + * if the RGB flag is set then 0 is red, 1 is green and 2 is blue; + * otherwise 0 is luma, 1 is chroma-U and 2 is chroma-V. */ AVComponentDescriptor comp[4]; @@ -126,14 +129,29 @@ typedef struct AVPixFmtDescriptor { * The pixel format contains RGB-like data (as opposed to YUV/grayscale). */ #define AV_PIX_FMT_FLAG_RGB (1 << 5) + /** - * The pixel format is "pseudo-paletted". This means that Libav treats it as - * paletted internally, but the palette is generated by the decoder and is not - * stored in the file. + * The pixel format is "pseudo-paletted". This means that it contains a + * fixed palette in the 2nd plane but the palette is fixed/constant for each + * PIX_FMT. This allows interpreting the data as if it was PAL8, which can + * in some cases be simpler. Or the data can be interpreted purely based on + * the pixel format without using the palette. + * An example of a pseudo-paletted format is AV_PIX_FMT_GRAY8 */ #define AV_PIX_FMT_FLAG_PSEUDOPAL (1 << 6) + /** - * The pixel format has an alpha channel. + * The pixel format has an alpha channel. This is set on all formats that + * support alpha in some way. The exception is AV_PIX_FMT_PAL8, which can + * carry alpha as part of the palette. Details are explained in the + * AVPixelFormat enum, and are also encoded in the corresponding + * AVPixFmtDescriptor. + * + * The alpha is always straight, never pre-multiplied. + * + * If a codec or a filter does not support alpha, it should set all alpha to + * opaque, or use the equivalent pixel formats without alpha component, e.g. + * AV_PIX_FMT_RGB0 (or AV_PIX_FMT_RGB24 etc.) instead of AV_PIX_FMT_RGBA. */ #define AV_PIX_FMT_FLAG_ALPHA (1 << 7) @@ -205,7 +223,7 @@ void av_write_image_line(const uint16_t *src, uint8_t *data[4], * For example in a little-endian system, first looks for "gray16", * then for "gray16le". * - * Finally if no pixel format has been found, returns PIX_FMT_NONE. + * Finally if no pixel format has been found, returns AV_PIX_FMT_NONE. */ enum AVPixelFormat av_get_pix_fmt(const char *name); @@ -219,7 +237,7 @@ const char *av_get_pix_fmt_name(enum AVPixelFormat pix_fmt); /** * Print in buf the string corresponding to the pixel format with - * number pix_fmt, or an header if pix_fmt is negative. + * number pix_fmt, or a header if pix_fmt is negative. * * @param buf the buffer where to write the string * @param buf_size the size of buf @@ -242,6 +260,12 @@ char *av_get_pix_fmt_string(char *buf, int buf_size, int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc); /** + * Return the number of bits per pixel for the pixel format + * described by pixdesc, including any padding or unused bits. + */ +int av_get_padded_bits_per_pixel(const AVPixFmtDescriptor *pixdesc); + +/** * @return a pixel format descriptor for provided pixel format or NULL if * this pixel format is unknown. */ @@ -266,9 +290,14 @@ enum AVPixelFormat av_pix_fmt_desc_get_id(const AVPixFmtDescriptor *desc); * Utility function to access log2_chroma_w log2_chroma_h from * the pixel format AVPixFmtDescriptor. * + * See av_get_chroma_sub_sample() for a function that asserts a + * valid pixel format instead of returning an error code. + * Its recommended that you use avcodec_get_chroma_sub_sample unless + * you do check the return code! + * * @param[in] pix_fmt the pixel format - * @param[out] h_shift store log2_chroma_h - * @param[out] v_shift store log2_chroma_w + * @param[out] h_shift store log2_chroma_w + * @param[out] v_shift store log2_chroma_h * * @return 0 on success, AVERROR(ENOSYS) on invalid or unknown pixel format */ @@ -291,6 +320,56 @@ int av_pix_fmt_count_planes(enum AVPixelFormat pix_fmt); */ enum AVPixelFormat av_pix_fmt_swap_endianness(enum AVPixelFormat pix_fmt); +#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 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. + * av_get_fix_fmt_loss() informs you about 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 + * (maximum loss for an invalid dst_pix_fmt). + */ +int av_get_pix_fmt_loss(enum AVPixelFormat dst_pix_fmt, + enum AVPixelFormat src_pix_fmt, + int has_alpha); + +/** + * Compute 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. + * av_get_fix_fmt_loss() informs you about 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 + * (maximum loss for an invalid dst_pix_fmt). + */ +enum AVPixelFormat av_find_best_pix_fmt_of_2(enum AVPixelFormat dst_pix_fmt1, enum AVPixelFormat dst_pix_fmt2, + enum AVPixelFormat src_pix_fmt, int has_alpha, int *loss_ptr); + /** * @return the name for provided color range or NULL if unknown. */ |