[FFmpeg-cvslog] swscale: organize and better document flags
Niklas Haas
git at videolan.org
Mon Nov 25 12:11:36 EET 2024
ffmpeg | branch: master | Niklas Haas <git at haasn.dev> | Thu Oct 10 15:56:32 2024 +0200| [fb1696400924e14e65f842a93300b95a23f849fa] | committer: Niklas Haas
swscale: organize and better document flags
Group them into an enum rather than random #defines, and document their
behavior a bit more obviously.
Of particular note, I discovered that SWS_DIRECT_BGR is not referenced
anywhere else in the code base. As such, I have moved it to the deprecated
section, alongside SWS_ERROR_DIFFUSION.
Sponsored-by: Sovereign Tech Fund
Signed-off-by: Niklas Haas <git at haasn.dev>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=fb1696400924e14e65f842a93300b95a23f849fa
---
doc/APIchanges | 3 ++
libswscale/swscale.h | 116 +++++++++++++++++++++++++++++----------------------
libswscale/version.h | 2 +-
3 files changed, 70 insertions(+), 51 deletions(-)
diff --git a/doc/APIchanges b/doc/APIchanges
index a0c6b2c82a..0d8ef0bbe3 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2024-03-07
API changes, most recent first:
+2024-11-25 - xxxxxxxxxx - lsws 8.11.100 - swscale.h
+ Replace #define-based SWS_* flags by enum SwsFlags.
+
2024-11-25 - xxxxxxxxxx - lsws 8.10.100 - swscale.h
Publicly expose struct SwsContext, enum SwsDither, and enum SwsAlphaBlend.
diff --git a/libswscale/swscale.h b/libswscale/swscale.h
index 4baef532b6..3996411dc8 100644
--- a/libswscale/swscale.h
+++ b/libswscale/swscale.h
@@ -91,6 +91,71 @@ typedef enum SwsAlphaBlend {
SWS_ALPHA_BLEND_NB, /* not part of the ABI */
} SwsAlphaBlend;
+typedef enum SwsFlags {
+ /**
+ * Scaler selection options. Only one may be active at a time.
+ */
+ SWS_FAST_BILINEAR = 1 << 0, ///< fast bilinear filtering
+ SWS_BILINEAR = 1 << 1, ///< bilinear filtering
+ SWS_BICUBIC = 1 << 2, ///< 2-tap cubic B-spline
+ SWS_X = 1 << 3, ///< experimental
+ SWS_POINT = 1 << 4, ///< nearest neighbor
+ SWS_AREA = 1 << 5, ///< area averaging
+ SWS_BICUBLIN = 1 << 6, ///< bicubic luma, bilinear chroma
+ SWS_GAUSS = 1 << 7, ///< gaussian approximation
+ SWS_SINC = 1 << 8, ///< unwindowed sinc
+ SWS_LANCZOS = 1 << 9, ///< 3-tap sinc/sinc
+ SWS_SPLINE = 1 << 10, ///< cubic Keys spline
+
+ /**
+ * Emit verbose log of scaling parameters.
+ */
+ SWS_PRINT_INFO = 1 << 12,
+
+ /**
+ * Perform full chroma upsampling when upscaling to RGB.
+ *
+ * For example, when converting 50x50 yuv420p to 100x100 rgba, setting this flag
+ * will scale the chroma plane from 25x25 to 100x100 (4:4:4), and then convert
+ * the 100x100 yuv444p image to rgba in the final output step.
+ *
+ * Without this flag, the chroma plane is instead scaled to 50x100 (4:2:2),
+ * with a single chroma sample being re-used for both of the horizontally
+ * adjacent RGBA output pixels.
+ */
+ SWS_FULL_CHR_H_INT = 1 << 13,
+
+ /**
+ * Perform full chroma interpolation when downscaling RGB sources.
+ *
+ * For example, when converting a 100x100 rgba source to 50x50 yuv444p, setting
+ * this flag will generate a 100x100 (4:4:4) chroma plane, which is then
+ * downscaled to the required 50x50.
+ *
+ * Without this flag, the chroma plane is instead generated at 50x100 (dropping
+ * every other pixel), before then being downscaled to the required 50x50
+ * resolution.
+ */
+ SWS_FULL_CHR_H_INP = 1 << 14,
+
+ /**
+ * Force bit-exact output. This will prevent the use of platform-specific
+ * optimizations that may lead to slight difference in rounding, in favor
+ * of always maintaining exact bit output compatibility with the reference
+ * C code.
+ *
+ * Note: It is recommended to set both of these flags simultaneously.
+ */
+ SWS_ACCURATE_RND = 1 << 18,
+ SWS_BITEXACT = 1 << 19,
+
+ /**
+ * Deprecated flags.
+ */
+ SWS_DIRECT_BGR = 1 << 15, ///< This flag has no effect
+ SWS_ERROR_DIFFUSION = 1 << 23, ///< Set `SwsContext.dither` instead
+} SwsFlags;
+
/***********************************
* Context creation and management *
***********************************/
@@ -109,7 +174,7 @@ typedef struct SwsContext {
void *opaque;
/**
- * Bitmask of SWS_*.
+ * Bitmask of SWS_*. See `SwsFlags` for details.
*/
unsigned flags;
@@ -225,60 +290,11 @@ int sws_test_frame(const AVFrame *frame, int output);
*/
int sws_is_noop(const AVFrame *dst, const AVFrame *src);
-/* values for the flags, the stuff on the command line is different */
-#define SWS_FAST_BILINEAR 1
-#define SWS_BILINEAR 2
-#define SWS_BICUBIC 4
-#define SWS_X 8
-#define SWS_POINT 0x10
-#define SWS_AREA 0x20
-#define SWS_BICUBLIN 0x40
-#define SWS_GAUSS 0x80
-#define SWS_SINC 0x100
-#define SWS_LANCZOS 0x200
-#define SWS_SPLINE 0x400
-
#define SWS_SRC_V_CHR_DROP_MASK 0x30000
#define SWS_SRC_V_CHR_DROP_SHIFT 16
#define SWS_PARAM_DEFAULT 123456
-#define SWS_PRINT_INFO 0x1000
-
-//the following 3 flags are not completely implemented
-
-/**
- * Perform full chroma upsampling when upscaling to RGB.
- *
- * For example, when converting 50x50 yuv420p to 100x100 rgba, setting this flag
- * will scale the chroma plane from 25x25 to 100x100 (4:4:4), and then convert
- * the 100x100 yuv444p image to rgba in the final output step.
- *
- * Without this flag, the chroma plane is instead scaled to 50x100 (4:2:2),
- * with a single chroma sample being re-used for both of the horizontally
- * adjacent RGBA output pixels.
- */
-#define SWS_FULL_CHR_H_INT 0x2000
-
-/**
- * Perform full chroma interpolation when downscaling RGB sources.
- *
- * For example, when converting a 100x100 rgba source to 50x50 yuv444p, setting
- * this flag will generate a 100x100 (4:4:4) chroma plane, which is then
- * downscaled to the required 50x50.
- *
- * Without this flag, the chroma plane is instead generated at 50x100 (dropping
- * every other pixel), before then being downscaled to the required 50x50
- * resolution.
- */
-#define SWS_FULL_CHR_H_INP 0x4000
-
-#define SWS_DIRECT_BGR 0x8000
-
-#define SWS_ACCURATE_RND 0x40000
-#define SWS_BITEXACT 0x80000
-#define SWS_ERROR_DIFFUSION 0x800000
-
#define SWS_MAX_REDUCE_CUTOFF 0.002
#define SWS_CS_ITU709 1
diff --git a/libswscale/version.h b/libswscale/version.h
index a5f5b2e3c7..16459ca9f7 100644
--- a/libswscale/version.h
+++ b/libswscale/version.h
@@ -28,7 +28,7 @@
#include "version_major.h"
-#define LIBSWSCALE_VERSION_MINOR 10
+#define LIBSWSCALE_VERSION_MINOR 11
#define LIBSWSCALE_VERSION_MICRO 100
#define LIBSWSCALE_VERSION_INT AV_VERSION_INT(LIBSWSCALE_VERSION_MAJOR, \
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