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/*
* Copyright (c) 2021, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 3-Clause Clear License and the
* Alliance for Open Media Patent License 1.0. If the BSD 3-Clause Clear License was
* not distributed with this source code in the LICENSE file, you can obtain it
* at aomedia.org/license/software-license/bsd-3-c-c/. If the Alliance for Open Media Patent
* License 1.0 was not distributed with this source code in the PATENTS file, you
* can obtain it at aomedia.org/license/patent-license/.
*/
The Lanczos resampling library and utilities are developed by Google
initially and contributed to the Alliance for open Media for experiments
related to super-resolution and Adaptive Streaming use cases.
For questions and technical support, please contact debargha@google.com
LIBRARY
#######
The main library source and header files are:
lanczos_resample.c
lanczos_resample.h
UTILITIES
#########
Two utilities are provided to resample y4m and yuv videos respectively:
lanczos_resample_y4m (built using source lanczos_resample_y4m.c)
lanczos_resample_y4m (built using source lanczos_resample_yuv.c)
Another utility simply returns the filter parameters for a given
resampling configuration:
lanczos_resample_filter (built using source lanczos_resample_filter.c)
lanczos_resample_y4m
--------------------
The usage of lanczos_resample_y4m is:
lanczos_resample_y4m
[<Options>]
<y4m_input>
<num_frames>
<horz_resampling_config>
<vert_resampling_config>
<y4m_output>
[<outwidth>x<outheight>]
Notes:
<Options> are optional switches prefixed by '-' as follows:
-bit:<n> - providing bits for filter taps
[default: 14]
-ieb:<n> - providing intermediate extra bits of
prec between horz and vert filtering
clamped to maximum of (15 - bitdepth)
[default: 2]
-ext:<ext_type> - providing the extension type
<ext_type> is one of:
'r' or 'rep' (Repeat)
's' or 'sym' (Symmetric)
'f' or 'ref' (Reflect/Mirror-whole)
'g' or 'gra' (Grafient preserving)
[default: 'r']
-win:<win_type> - providing the windowing function type
<win_type> is one of:
'lanczos' (Repeat)
'lanczos_dil' (Symmetric)
'gaussian' (Gaussian)
'gengaussian' (Generalized Gaussian)
'cosine' (Cosine)
'hamming (Hamming)
'blackman (Blackman)
'kaiser (Kaiser)
[default: 'lanczos']
<y4m_input> is the input video in Y4M format
<y4m_output> is the output video in Y4M format
<num_frames> is number of frames to be processed
<horz_resampling_config> and <vert_resampling_config>
are of the form:
<p>:<q>:<Lanczos_a>[:<x0>] where:
<p>/<q> gives the resampling ratio.
<Lanczos_a> is Lanczos parameter.
<x0> is the optional initial offset
[default: centered]
If used, it can be a number in (-1, 1),
or 'c' meaning centered.
which is a shortcut for x0 = (q-p)/(2p)
or 'd' meaning co-sited chroma with centered
luma for use only on sub-sampled chroma,
which is a shortcut for x0 = (q-p)/(4p)
The field can be prefixed by 'i' meaning
using the inverse of the number provided,
If it is desired to provide different config parameters
for luma and chroma, the <Lanczos_a> and <x0> fields
could be optionally converted to a pair of
comma-separated parameters as follows:
<p>:<q>:<Lanczos_al>,<lanczos_ac>[:<x0l>,<x0c>]
where <Lanczos_al> and <lanczos_ac> are
luma and chroma lanczos parameters
<x0l> and <x0c> are
luma and chroma initial offsets
<outwidth>x<outheight> is output video dimensions
only needed in case of upsampling
Resampling config of 1:1:1:0 horizontally or vertically
is regarded as a no-op in that direction
Example usages:
1a. Downsample 10 frames from Boat_1920x1080_60fps_10bit_420.y4m by
ratio 3/2 horizontally and 4/3 vertically with Lanczos parameter
6 for both and centered sampling.
lanczos_resample_y4m Boat_1920x1080_60fps_10bit_420.y4m 10 \
2:3:6 3:4:6 /tmp/down.y4m
1b. Reverse the process in 1a. That is, upsample 10 frames from
/tmp/boat.y4m by ratio 3/2 horizontally and 4/3 vertically with
Lanczos parameter 6 for both and centered sampling. The output
dimension desired is specified to be 1920x1080.
lanczos_resample_y4m /tmp/down.y4m 10 3:2:6 4:3:6 /tmp/downup.y4m 1920x1080
2a. Similar to 1a, except using left-aligned sampling
lanczos_resample_y4m Boat_1920x1080_60fps_10bit_420.y4m 10 \
2:3:6:0 3:4:6:0 /tmp/down.y4m
2b. Reversing the process in 2a.
lanczos_resample_y4m /tmp/down.y4m 10 3:2:6:0 4:3:6:0 /tmp/downup.y4m \
1920x1080
3a. Similar to 1a, except using a specified initial offset of 0.125 horizontally
and center aligned sampling vertically
lanczos_resample_y4m Boat_1920x1080_60fps_10bit_420.y4m 10 \
2:3:6:0.125 3:4:6 /tmp/down.y4m
3b. Reversing the process in 3a.
lanczos_resample_y4m /tmp/down.y4m 10 3:2:6:i0.125 4:3:6 /tmp/downup.y4m \
1920x1080
4a. Similar to 3a, except using symmetric border extension instead of default
repeat.
lanczos_resample_y4m -ext:sym Boat_1920x1080_60fps_10bit_420.y4m 10 \
2:3:6:0.125 3:4:6:c /tmp/down.y4m
4b. Reversing the process in 4a.
lanczos_resample_y4m -ext:sym /tmp/down.y4m 10 3:2:6:i0.125 4:3:6:c \
/tmp/downup.y4m 1920x1080
5a. Downsample 10 frames from Boat_1920x1080_60fps_10bit_420.y4m by
ratio 3/2 horizontally and vertically with Lanczos parameter
6 for both, centered sampling for luma, co-sited chroma horizontally
and centered chroma vertically. Note this is the most common use
case encountered in practice.
lanczos_resample_y4m Boat_1920x1080_60fps_10bit_420.y4m 10 \
2:3:6:c,d 2:3:6 /tmp/down.y4m
5b. Reversing the process in 5a.
lanczos_resample_y4m /tmp/down.y4m 10 3:2:6:ic,id 3:2:6 \
/tmp/downup.y4m 1920x1080
6a. Similar to 5a except using symmetric border extension, 12-bit
filters, 3 bit intermediate extra precision, and hamming windowing.
lanczos_resample_y4m -ext:sym -bit:12 -ieb:3 -win:hamming \
Boat_1920x1080_60fps_10bit_420.y4m 10 \
2:3:6:c,d 2:3:6 /tmp/down.y4m
6b. Reversing the process in 6a.
lanczos_resample_y4m -ext:sym -bit:12 -ieb:3 -win:hamming \
/tmp/down.y4m 10 3:2:6:ic,id 3:2:6 \
/tmp/downup.y4m 1920x1080
lanczos_resample_yuv
--------------------
The usage of lanczos_resample_yuv is similar but with two extra
arguments to specify the input format:
lanczos_resample_yuv
[<Options>]
<yuv_input>
<width>x<height>
<pix_format>
<num_frames>
<horz_resampling_config>
<vert_resampling_config>
<yuv_output>
[<outwidth>x<outheight>]
Notes:
<yuv_input> is the input video in raw YUV format
<yuv_output> is the output video in raw YUV format
<width>x<height> is input video dimensions.
<pix_format> is one of { yuv420p, yuv420p10, yuv420p12,
yuv422p, yuv422p10, yuv422p12,
yuv444p, yuv444p10, yuv444p12 }
All other parameters are the same as the ones used for
lanczos_resample_y4m described above.
lanczos_resample_filter
-----------------------
Utility to show the filter parameters used for both luma and chroma.
The usage of lanczos_resample_filter is:
lanczos_resample_filter
[<Options>]
<resampling_config>
Notes:
<resampling_config> is in the same format as one specified
in lanczos_resample_y4m above for <horz_resampling_config>
or <vert_resampling_config>.
Example usages:
7a. lanczos_resample_filter -bit:14 2:3:6
(shows 14-bit a = 6 filter for 2/3 resampling, x0 = centered)
7b. lanczos_resample_filter -bit:12 1:2:5:0.125
(shows 12-bit a = 5 filter for 1/2 resampling, x0 = 0.125)
7c. lanczos_resample_filter -bit:12 1:2:5:c,d 12
(shows 12-bit a = 5 filter for 1/2 resampling,
x0 = centered for luma, co-sited for chroma)
7d. lanczos_resample_filter -bit:12 3:2:6:i0.125 12
(shows 12-bit a = 5 filter for 3/2 resampling, x0 = inverse of 0.125)
SCRIPTS
#######
In addition to these utilities, two convenience scripts are provided:
lanczos_downup.sh
lanczos_downcompup.sh
They can be invoked from the build directory directly after a build that
produces lanczos_resample_y4m, aomenc and aomdec applications.
lanczos_downup.sh
-----------------
The script lanczos_downup.sh resamples a video with specified parameters
and then reverses the process using two lanczos_resample_y4m commands.
The usage for the script is:
Usage:
lanczos_downup.sh [<Options>]
<input_y4m>
<num_frames>
<horz_resampling_config>
<vert_resampling_config>
<downup_y4m>
[<down_y4m>]
Notes:
<Options> are optional switches similar to what is used by
lanczos_resample_y4m utility
<y4m_input> is input y4m video
<num_frames> is number of frames to process
<horz_resampling_config> and <vert_resampling_config> are in format:
<p>:<q>:<Lanczos_a_str>[:<x0>]
similar to what is used by lanczos_resample_y4m utility, with the
enhancement that for <Lanczos_a_str> optionally
two '^'-separated strings for 'a' could be provided instead
of one for down and up-sampling operations respectively if different.
Note each string separated by '^' could have two values for luma
and chroma separated by ','.
So <Lanczos_a_str> could be of the form:
<a_luma_down>,<a_chroma_down>^<a_luma_up>,<a_chroma_up>
if down and up operations use different parameters, or
<a_luma_down>,<a_chroma_down>
if down and up operations use the same parameters.
<downup_y4m> is the output y4m video.
<down_y4m> provides the intermediate resampled file as an
optional parameter. If skipped the intermediate resampled
file is deleted.
Example usages:
8. Similar to combined use cases 1a and 1b above including both
down and inverse up steps.
8a. From build directory run:
/path/to/script/lanczos_downup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:6 3:4:6 /tmp/downup.y4m
[Here the intermediate resampled files is not stored]
8b. From build directory run:
/path/to/script/lanczos_downup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:6 3:4:6 /tmp/downup.y4m \
/tmp/down.y4m
[Here the intermediate resampled file is stored in /tmp/down.y4m]
8c. From build directory run:
/path/to/script/lanczos_downup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:8^4 3:4:8^4 /tmp/downup.y4m
[Here Lanczos parameters 8 and 4 are used for down and upscaling
respectively]
8d. From build directory run:
/path/to/script/lanczos_downup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:6,4^6,4:c,d 3:4:6,4^6,4 /tmp/downup.y4m
[Here Lanczos parameters 6 and 4 are used for luma and chroma
respectively for both down and upscaling. Further centered
luma and co-sited chroma are used horizontally, while centered
luma and chroma sampling are used vertically.]
lanczos_downcompup.sh
---------------------
The script lanczos_downcompup.sh resamples a video with specified parameters
using lanczos_resample_y4m, then comprsses and decompresses using aomenc and
aomdec respectively, and finally reverse resamples the decompressed video to
the source resolution using another lanczos_resample_y4m command.
The usage for the script is:
Usage:
lanczos_downcompup.sh [<Options>]
<input_y4m>
<num_frames>
<horz_resampling_config>
<vert_resampling_config>
<cq_level>[:<cpu_used>]
<downcompup_y4m>
[[<down_y4m>]:[<downcomp_bit>]:[<downcomp_y4m]]
Notes:
<Options> are optional switches similar to what is used by
lanczos_resample_y4m utility
<y4m_input> is input y4m video
<num_frames> is number of frames to process
<horz_resampling_config> and <vert_resampling_config> are in format:
<p>:<q>:<Lanczos_a_str>[:<x0>]
similar to what is used by lanczos_resample_y4m utility, with the
enhancement that for <Lanczos_a_str> optionally
two '^'-separated strings for 'a' could be provided instead
of one for down and up-sampling operations respectively if different.
Note each string separated by '^' could have two values for luma
and chroma separated by ','.
So <Lanczos_a_str> could be of the form:
<a_luma_down>,<a_chroma_down>^<a_luma_up>,<a_chroma_up>
if down and up operations use different parameters, or
<a_luma_down>,<a_chroma_down>
if down and up operations use the same parameters.
<cq_level>[:<cpu_used>] provides the cq_level parameter of
compression along with an optional cpu_used parameter.
<downcompup_y4m> is the output y4m video.
The last param [[<down_y4m>]:[<downcomp_bit>]:[<downcomp_y4m]]
provides names of intermediate files where:
<down_y4m> is the resampled source
<downcomp_bit> is the compressed resampled bitstream
<downcomp_y4m> is the reconstructed bitstream.
This parameter string is entirely optional.
Besides if provided, each of <down_y4m>, <downcomp_bit> and
<downcomp_y4m> are optional by themselves where each can be
either provided or empty. If empty the corresponding
intermediate file is deleted.
Example usages:
9. Similar to use cases 8 above with a compression step in between.
9a. From build directory run:
/path/to/script/lanczos_downcompup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:6 3:4:6 40:5 /tmp/downup.y4m
[Here no intermediate files are stored.
Compression is at cq_level 40 and cpu_used=5]
9b. From build directory run:
/path/to/script/lanczos_downcompup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:6 3:4:6 40:5 /tmp/downup.y4m \
/tmp/down.y4m::/tmp/downrec.y4m
[Here the resampled source and its compressed reconstruction are
stoted in /tmp/down.y4m and /tmp/downrec.y4m respectively.
Compression is at cq_level 40 and cpu_used=5].
9c. From build directory run:
/path/to/script/lanczos_downcompup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:6 3:4:6 40:5 /tmp/downup.y4m \
/tmp/down.y4m:/tmp/down.bit:/tmp/downrec.y4m
[Here the resampled source, its compressed bitstream, and the
conpressed reconstruction are stoted in /tmp/down.y4m,
/tmp/downcomp.bit and /tmp/downrec.y4m respectively.
Compression is at cq_level 40 and cpu_used=5].
9d. From build directory run:
/path/to/script/lanczos_downcompup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:8^4 3:4:8^4 40:5 /tmp/downup.y4m
[Here Lanczos parameters 8 and 4 are used for down and upscaling
respectively.
Compression is at cq_level 40 and cpu_used=5].
9e. From build directory run:
/path/to/script/lanczos_downcompup.sh Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:6,4^6,4:c,d 3:4:6,4^6,4 40:5 /tmp/downup.y4m
[Here Lanczos parameters 6 and 4 are used for luma and chroma
respectively for both down and upscaling. Further centered
luma sampling and co-sited chroma sampling are respectively used
in the horizontal direction, while centered sampling is used for
both luma and chroma vertically.
Compression is at cq_level 40 and cpu_used=5].
9f. From build directory run:
/path/to/script/lanczos_downcompup.sh -win:kaiser \
Boat_1920x1080_60fps_10bit_420.y4m \
10 2:3:5:c,d 3:4:5 40:5 /tmp/downup.y4m
[Here Lanczos parameter 5 is used for luma and chroma both
horizontally and vertically, Further, centered luma
sampling and co-sited chroma sampling are used respectively
in the horizontal direction, while centered sampling is used
for both luma and chroma vertically.
Compression is at cq_level 40 and cpu_used=5].