avfilter: Constify all AVFilters

[ffmpeg] / doc / swscale.txt

diff --git a/doc/swscale.txt b/doc/swscale.txt
index 6c849426275a7a5e9a4133b639e61515225f4274..dbb4e2901ecc83bfaa2f2557f1e6e474e605a26a 100644 (file)
--- a/doc/swscale.txt
+++ b/doc/swscale.txt
@@ -10,12 +10,12 @@ Current (simplified) Architecture:
                /                       \
        special converter     [Input to YUV converter]
               |                         |
                /                       \
        special converter     [Input to YUV converter]
               |                         |

-              |          (8bit YUV 4:4:4 / 4:2:2 / 4:2:0 / 4:0:0 )
+              |         (8-bit YUV 4:4:4 / 4:2:2 / 4:2:0 / 4:0:0 )

               |                         |
               |                         v
               |                  Horizontal scaler
               |                         |
               |                         |
               |                         v
               |                  Horizontal scaler
               |                         |

-              |      (15bit YUV 4:4:4 / 4:2:2 / 4:2:0 / 4:1:1 / 4:0:0 )
+              |     (15-bit YUV 4:4:4 / 4:2:2 / 4:2:0 / 4:1:1 / 4:0:0 )

               |                         |
               |                         v
               |          Vertical scaler and output converter
               |                         |
               |                         v
               |          Vertical scaler and output converter


@@ -24,77 +24,75 @@ Current (simplified) Architecture:
                          output
 
 
                          output
 
 

-Swscale has 2 scaler pathes, each side must be capable to handle
-slices, that is consecutive non overlapping rectangles of dimension
-(0,slice_top) - (picture_width, slice_bottom)
+Swscale has 2 scaler paths. Each side must be capable of handling
+slices, that is, consecutive non-overlapping rectangles of dimension
+(0,slice_top) - (picture_width, slice_bottom).

 
 special converter
 
 special converter

-    This generally are unscaled converters of common
-    formats, like YUV 4:2:0/4:2:2 -> RGB15/16/24/32. Though it could also
+    These generally are unscaled converters of common
+    formats, like YUV 4:2:0/4:2:2 -> RGB12/15/16/24/32. Though it could also

     in principle contain scalers optimized for specific common cases.
 
 Main path
     in principle contain scalers optimized for specific common cases.
 
 Main path

-    The main path is used when no special converter can be used, the code
-    is designed as a destination line pull architecture. That is for each
+    The main path is used when no special converter can be used. The code
+    is designed as a destination line pull architecture. That is, for each

     output line the vertical scaler pulls lines from a ring buffer. When
     output line the vertical scaler pulls lines from a ring buffer. When

-    the ring buffer does not contain the wanted line then it is pulled from
-    the input slice through the input converter and horizontal scaler, and
-    the result is also stored in the ring buffer to serve future vertical
+    the ring buffer does not contain the wanted line, then it is pulled from
+    the input slice through the input converter and horizontal scaler.
+    The result is also stored in the ring buffer to serve future vertical

     scaler requests.
     When no more output can be generated because lines from a future slice
     would be needed, then all remaining lines in the current slice are
     converted, horizontally scaled and put in the ring buffer.
     scaler requests.
     When no more output can be generated because lines from a future slice
     would be needed, then all remaining lines in the current slice are
     converted, horizontally scaled and put in the ring buffer.

-    [this is done for luma and chroma, each with possibly different numbers
-     of lines per picture]
+    [This is done for luma and chroma, each with possibly different numbers
+     of lines per picture.]

 
 Input to YUV Converter
 
 Input to YUV Converter

-    When the input to the main path is not planar 8bit per component yuv or
-    8bit gray then it is converted to planar 8bit YUV, 2 sets of converters
-    exist for this currently one performing horizontal downscaling by 2
-    before the convertion and the other leaving the full chroma resolution
-    but being slightly slower. The scaler will try to preserve full chroma
-    here when the output uses it, its possible to force full chroma with
-    SWS_FULL_CHR_H_INP though even for cases where the scaler thinks its
-    useless.
+    When the input to the main path is not planar 8 bits per component YUV or
+    8-bit gray, it is converted to planar 8-bit YUV. Two sets of converters
+    exist for this currently: One performs horizontal downscaling by 2
+    before the conversion, the other leaves the full chroma resolution,
+    but is slightly slower. The scaler will try to preserve full chroma
+    when the output uses it. It is possible to force full chroma with
+    SWS_FULL_CHR_H_INP even for cases where the scaler thinks it is useless.

 
 Horizontal scaler
 
 Horizontal scaler

-    There are several horizontal scalers, a special case worth mentioning is
-    the fast bilinear scaler that is made of runtime generated mmx2 code
+    There are several horizontal scalers. A special case worth mentioning is
+    the fast bilinear scaler that is made of runtime-generated MMXEXT code

     using specially tuned pshufw instructions.
     using specially tuned pshufw instructions.

-    The remaining scalers are specially tuned for various filter lengths
-    they scale 8bit unsigned planar data to 16bit signed planar data.
-    Future >8bit per component inputs will need to add a new scaler here
-    that preserves the input precission.
+    The remaining scalers are specially-tuned for various filter lengths.
+    They scale 8-bit unsigned planar data to 16-bit signed planar data.
+    Future >8 bits per component inputs will need to add a new horizontal
+    scaler that preserves the input precision.

 
 Vertical scaler and output converter
 
 Vertical scaler and output converter

-    There is a large number of combined vertical scalers+output converters
+    There is a large number of combined vertical scalers + output converters.

     Some are:
     * unscaled output converters
     * unscaled output converters that average 2 chroma lines
     * bilinear converters                (C, MMX and accurate MMX)
     * arbitrary filter length converters (C, MMX and accurate MMX)
     And
     Some are:
     * unscaled output converters
     * unscaled output converters that average 2 chroma lines
     * bilinear converters                (C, MMX and accurate MMX)
     * arbitrary filter length converters (C, MMX and accurate MMX)
     And

-    * Plain C  8bit 4:2:2 YUV -> RGB converters using LUTs
-    * Plain C 17bit 4:4:4 YUV -> RGB converters using multiplies
-    * MMX     11bit 4:2:2 YUV -> RGB converters
-    * Plain C 16bit Y -> 16bit gray
+    * Plain C  8-bit 4:2:2 YUV -> RGB converters using LUTs
+    * Plain C 17-bit 4:4:4 YUV -> RGB converters using multiplies
+    * MMX     11-bit 4:2:2 YUV -> RGB converters
+    * Plain C 16-bit Y -> 16-bit gray

       ...
 
       ...
 

-    RGB with less than 8bit per component uses dither to improve the
-    subjective quality and low frequency accuracy.
+    RGB with less than 8 bits per component uses dither to improve the
+    subjective quality and low-frequency accuracy.

 
 
 Filter coefficients:
 --------------------
 
 
 Filter coefficients:
 --------------------

-There are several different scalers (bilinear, bicubic, lanczos, area, sinc, ...)
-Their coefficients are calculated in initFilter().
-Horinzontal filter coeffs have a 1.0 point at 1<<14, vertical ones at 1<<12.
-The 1.0 points have been choosen to maximize precission while leaving a
-little headroom for convolutional filters like sharpening filters and
+There are several different scalers (bilinear, bicubic, lanczos, area,
+sinc, ...). Their coefficients are calculated in initFilter().
+Horizontal filter coefficients have a 1.0 point at 1 << 14, vertical ones at
+1 << 12. The 1.0 points have been chosen to maximize precision while leaving
+a little headroom for convolutional filters like sharpening filters and

 minimizing SIMD instructions needed to apply them.
 It would be trivial to use a different 1.0 point if some specific scaler
 would benefit from it.
 minimizing SIMD instructions needed to apply them.
 It would be trivial to use a different 1.0 point if some specific scaler
 would benefit from it.

-Also as already hinted at initFilter() accepts an optional convolutional
+Also, as already hinted at, initFilter() accepts an optional convolutional

 filter as input that can be used for contrast, saturation, blur, sharpening
 shift, chroma vs. luma shift, ...
 filter as input that can be used for contrast, saturation, blur, sharpening
 shift, chroma vs. luma shift, ...

-