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1st November 2014, 01:45 | #1 | Link |
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Scaling, colorspace conversion, and dithering library
Some folks have expressed interest in having a program library to perform the common tasks of manipulating resolution, colorspace, and depth. The "z" library (name subject to change) provides a simple interface to perform those tasks. An open source Vapoursynth plugin is provided, demonstrating the usage of the API.
Code:
NAME: z - z.lib for VapourSynth SYNOPSIS: z.Format(clip clip, int "width", int "height", int "format", enum "matrix", enum "transfer", enum "primaries", enum "range", enum "chromaloc", enum "matrix_in", enum "transfer_in", enum "primaries_in", enum "range_in", enum "chromaloc_in", string "resample_filter", float "filter_param_a", float "filter_param_b", string "resample_filter_uv", float "filter_param_a_uv", float "filter_param_b_uv", string "dither_type") z.Subresize(clip clip, int width, int height, float "shift_w", float "shift_h", float "subwidth", float "subheight", string "resample_filter", float "filter_param_a", float "filter_param_b", string "dither_type") DESCRIPTION: z.Format is a drop-in replacement for the built-in VapourSynth resize functions. It converts a clip of known or unknown format to another clip of known or unknown format, changing only the parameters specified by the user. z.Subresize provides advanced resampling capabilities intended for use by script writers. Arguments denoted as type "enum" may be specified by numerical index (see ITU-T H.265 Annex E.3) or by name. Enums specified by name have their argument name suffixed with "_s". clip: input clip The input may be of COMPAT color family (requires VS R28). width, height: output image dimensions format: output format preset id The output may be of COMPAT color family (requires VS R28). matrix, transfer, primaries: output colorspace specification If not provided, the corresponding attribute from the input clip will be selected, except for YCoCg and RGB color families, where the corresponding matrix is set by default. range: output pixel range For integer formats, this allows selection of the legal code values. Even when set, out of range values (BTB/WTW) may be generated. If the input format is of a different color family, the default range is studio/limited for YUV and full-range for RGB. chromaloc: output chroma location For subsampled formats, specifies the chroma location. If the input format is 4:4:4 or RGB and the output is subsampled, the default location is left-aligned, as per MPEG. matrix_in, transfer_in, primaries_in, range_in, chromaloc_in: input colorspace/format specification If the corresponding frame property is set to a value other than unspecified, the frame property is used instead of this parameter. Default values are set for certain color families. resample_filter, filter_param_a, filter_param_b: scaling method for RGB and Y-channel For the bicubic filter, filter_param_a/b represent the "b" and "c" parameters. For the lanczos filter, filter_param_a represents the number of taps. resample_filter_uv, resample_filter_uv_a, resample_filter_uv_b: scaling method for UV channels dither_type: dithering method Dithering is used only for conversions resulting in an integer format. shift_w, shift_h: offset of image top-left corner The top-left image corner is assumed to be at coordinate (0, 0) and the first sample centered at coordinate (0.5, 0.5). An offset may be applied to the assumed image origin to "shift" the image. subwidth, subheight: fractional dimensions of input image The input image is assumed to span from its origin a distance equal to its dimensions in pixels. An alternative image resolution may be specified. The following tables list values of selected colorspace enumerations and their abbreviated names. For all possible values, see ITU-T H.265. Matrix coefficients (ITU-T H.265 Table E.5): rgb Identity The identity matrix. Typically used for GBR (often referred to as RGB); however, may also be used for YZX (often referred to as XYZ); 709 KR = 0.2126; KB = 0.0722 ITU-R Rec. BT.709-5 unspec Unspecified Image characteristics are unknown or are determined by the application. 470bg KR = 0.299; KB = 0.114 ITU-R Rec. BT.470-6 System B, G (historical) (functionally the same as the value 6 (170m)) 170m KR = 0.299; KB = 0.114 SMPTE 170M (2004) (functionally the same as the value 5 (470bg)) ycgco YCgCo 2020ncl KR = 0.2627; KB = 0.0593 Rec. ITU-R BT.2020 non-constant luminance system 2020cl KR = 0.2627; KB = 0.0593 Rec. ITU-R BT.2020 constant luminance system Transfer characteristics (ITU-T H.265 Table E.4): 709 V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b V = 4.500 * Lc for b > Lc >= 0 Rec. ITU-R BT.709-5 (functionally the same as the values 6 (601), 14 (2020_10) and 15 (2020_12)) unspec Unspecified Image characteristics are unknown or are determined by the application. 601 V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b V = 4.500 * Lc for b > Lc >= 0 Rec. ITU-R BT.601-6 525 or 625 (functionally the same as the values 1 (709), 14 (2020_10) and 15 (2020_12)) linear V = Lc for all values of Lc Linear transfer characteristics 2020_10 V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b V = 4.500 * Lc for b > Lc >= 0 Rec. ITU-R BT.2020 (functionally the same as the values 1 (709), 6 (601) and 15 (2020_12)) 2020_12 V = a * Lc0.45 - ( a - 1 ) for 1 >= Lc >= b V = 4.500 * Lc for b > Lc >= 0 Rec. ITU-R BT.2020 (functionally the same as the values 1 (709), 6 (601) and 14 (2020_10)) Color primaries (ITU-T H.265 Table E.3): 709 primary x y green 0.300 0.600 blue 0.150 0.060 red 0.640 0.330 white D65 0.3127 0.3290 Rec. ITU-R BT.709-5 unspec Unspecified Image characteristics are unknown or are determined by the application. 170m primary x y green 0.310 0.595 blue 0.155 0.070 red 0.630 0.340 white D65 0.3127 0.3290 SMPTE 170M (2004) (functionally the same as the value 7 (240m)) 240m primary x y green 0.310 0.595 blue 0.155 0.070 red 0.630 0.340 white D65 0.3127 0.3290 SMPTE 240M (1999) (functionally the same as the value 6 (170m)) 2020 primary x y green 0.170 0.797 blue 0.131 0.046 red 0.708 0.292 white D65 0.3127 0.3290 Rec. ITU-R BT.2020 Pixel range (ITU-T H.265 Eq E-4 to E-15): limited Y = Clip1Y( Round( ( 1 << ( BitDepthY - 8 ) ) * ( 219 * E'Y + 16 ) ) ) Cb = Clip1C( Round( ( 1 << ( BitDepthC - 8 ) ) * ( 224 * E'PB + 128 ) ) ) Cr = Clip1C( Round( ( 1 << ( BitDepthC - 8 ) ) * ( 224 * E'PR + 128 ) ) ) R = Clip1Y( ( 1 << ( BitDepthY - 8 ) ) * ( 219 * E'R + 16 ) ) G = Clip1Y( ( 1 << ( BitDepthY - 8 ) ) * ( 219 * E'G + 16 ) ) B = Clip1Y( ( 1 << ( BitDepthY - 8 ) ) * ( 219 * E'B + 16 ) ) full Y = Clip1Y( Round( ( ( 1 << BitDepthY ) - 1 ) * E'Y ) ) Cb = Clip1C( Round( ( ( 1 << BitDepthC ) - 1 ) * E'PB + ( 1 << ( BitDepthC - 1 ) ) ) ) Cr = Clip1C( Round( ( ( 1 << BitDepthC ) - 1 ) * E'PR + ( 1 << ( BitDepthC - 1 ) ) ) ) R = Clip1Y( ( ( 1 << BitDepthY ) - 1 ) * E'R ) G = Clip1Y( ( ( 1 << BitDepthY ) - 1 ) * E'G ) B = Clip1Y( ( ( 1 << BitDepthY ) - 1 ) * E'B ) Chroma location (ITU-T H.265 Figure E.1): left center top_left top bottom_left bottom The following scaling methods are available: point, bilinear, bicubic, spline16, spline36, lanczos The following dithering methods are available: none, ordered, random, error_diffusion Last edited by Stephen R. Savage; 7th December 2015 at 07:55. Reason: v2.0.2 |
30th November 2014, 02:15 | #4 | Link |
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After much (?) work, I am pleased to announce the release of "zlib" v1.0 FINAL. The library and VapourSynth example are linked in the frist post. Work is underway to improve the multithreaded scalability of the software, making it a better fit for playback scenarios
Last edited by Stephen R. Savage; 30th November 2014 at 02:17. |
30th November 2014, 16:02 | #5 | Link | |
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Could you add some noise generator? I found that Floyd Steinberg dithering with a tiny amount of noise gives very good results. This small noise helps to cover contouring left after dithering. Another thing is Filter Light algorithm, which is close to Floyd, but apparently waay faster. Last edited by kolak; 30th November 2014 at 16:05. |
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7th December 2014, 15:49 | #8 | Link |
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Question of the day :
What you guys have with cats ? Answer of the day : I tried the filter on my Odroid-U2 (unlike fmtconv, it doesn't throw me SSE2 errors) for resizing/cropping a 1920x1080 Blu-Ray to 1280x536. Swscale is 2x as fast as zlib (8.79fps against 4.36fps). It's probably caused by the lack of NEON optimizations. |
17th April 2015, 17:58 | #9 | Link |
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Thanks for your reply!
This build fixes the magnitude of ordered dither (to 0.5), which solved lots of problems. The underflow issues is solved, but the overflow issues for 9-15bit still exists. 2. Not only full range YUV can produce this kind of overflow issue, but also limited range RGB/YUV with out of range value, such as reducing 65535 to 9-15bit with dithering, or converting 65535 from limited range 16bit to full range 9-15bit. Thus, IMO this may lead to potential problems in practice, since we may not guarantee the input image is perfect. Acctually converting to 9-15bit is not so often used except in the case of final output, so I prefer safe output rather than performance or intermediate precision. Perhaps an additional option for clamping the result to valid range can be added? Also it can be used for limiting the value to limited range when fullrange_out=False. 3. My mistake, the ordered dither does affect only the least significant bit of the output, maybe I was misled by the image with underflow issues. In the previous build, when the output depth & range are the same as input, the ordered dithering pattern still applies to the image. After fixing the magnitude issue of ordered dither it's also solved. I suppose it will be faster to directly return the src frame pointer on this condition, since the frame data is always unchanged. 4. Yes, I got it. |
18th April 2015, 21:08 | #10 | Link |
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I see. This will make this filter clean and clear. On the other side, the users need to be aware of what they are doing and take more care of such risks on these special conditions.
Anyway, this is a great library and thanks for your efforts! |
7th June 2015, 03:39 | #12 | Link | |
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Code:
# YUV420P8 input src = core.z.Depth(src, depth=16, fullrange_in=False) src = core.z.Resize(src, src.width, src.height, filter_uv="bicubic", filter_param_a_uv=1/3, filter_param_b_uv=1/3, subsample_w=0, subsample_h=0) src = core.z.Colorspace(src, matrix_in=1, transfer_in=1, primaries_in=1, matrix_out=0, transfer_out=1, primaries_out=1) # RGB48 output Quote:
Last edited by mawen1250; 7th June 2015 at 04:54. |
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15th August 2015, 13:24 | #13 | Link |
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zimg-1.1.1 crashes VS for unknown reason, after running a script for some time(about 70-100s in my tests).
Windows 7 x64 VapourSynth R27 x64 threads=8 I just found that using BM3D built with MSVC14 also introduces the same problem (64bit crashes, 32bit doesn't in my test). Considering zimg-1.1.1 is also built with MSVC14, could this be some problems related to VapourSynth and MSVC14? Last edited by mawen1250; 15th August 2015 at 13:31. |
15th August 2015, 13:37 | #14 | Link | |
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Quote:
like this? 80% sure it's a vs2015 issue |
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8th October 2015, 16:26 | #16 | Link |
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two issues about 1.95 Beta:
1. If the clip is first cropped with std.CropAbs/std.CropRel and the width is not mod16, right-most pixels are corrupt. 2. no arguments for shift_w, shift_h, subwidth, subheight Last edited by mawen1250; 8th October 2015 at 17:20. |
8th October 2015, 18:14 | #17 | Link | |
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Quote:
2. Is there a use case for this that's not covered by specifying chromaloc? Last edited by Stephen R. Savage; 8th October 2015 at 19:02. |
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9th October 2015, 04:50 | #18 | Link | |
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Quote:
2. to do top-left aligned resampling, for example mv.Super and warp.AWarp may need it 3. any other time you want to do a (sub-pixel) cropping/padding |
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24th October 2015, 11:49 | #19 | Link |
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Looks like around 32 threads 'engine' gets saturated in terms of threading.
How does the threading work- some slices? Does it mean higher resolution will scale better? Latest ffmpeg added zscale filter, which I think is great news! |
24th October 2015, 22:50 | #20 | Link |
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I meant: performance doesn't scale linear with cores. Provided graphs show big speed/core performance drop with bigger core numbers. Speed still rises, but we are wasting many cores and CPU power to get eg. just 20% speedup.
I think my question is- does z library engine scales linearly with core numbers? If we would be able to deliver raw video data at unlimited speed and just measure z performace, would processing speed be linear with cores rise? Last edited by kolak; 24th October 2015 at 22:54. |
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