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doc/fftools-common-opts: update/extend documentation for -opencl_bench option

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Signed-off-by: Stefano Sabatini <stefasab@gmail.com>
This commit is contained in:
Maneesh Gupta
2015-01-27 20:28:24 +05:30
committed by Stefano Sabatini
parent fb34c580bb
commit 1600f85cbc
1 changed files with 35 additions and 2 deletions
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37
doc/fftools-common-opts.texi
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@@ -294,8 +294,41 @@ Possible flags for this option are:
@end table
@item -opencl_bench
Benchmark all available OpenCL devices and show the results. This option
is only available when FFmpeg has been compiled with @code{--enable-opencl}.
This option is used to benchmark all available OpenCL devices and print the
results. This option is only available when FFmpeg has been compiled with
@code{--enable-opencl}.
When FFmpeg is configured with @code{--enable-opencl}, the options for the
global OpenCL context are set via @option{-opencl_options}. See the
"OpenCL Options" section in the ffmpeg-utils manual for the complete list of
supported options. Amongst others, these options include the ability to select
a specific platform and device to run the OpenCL code on. By default, FFmpeg
will run on the first device of the first platform. While the options for the
global OpenCL context provide flexibility to the user in selecting the OpenCL
device of their choice, most users would probably want to select the fastest
OpenCL device for their system.
This option assists the selection of the most efficient configuration by
identifying the appropriate device for the user's system. The built-in
benchmark is run on all the OpenCL devices and the performance is measured for
each device. The devices in the results list are sorted based on their
performance with the fastest device listed first. The user can subsequently
invoke @command{ffmpeg} using the device deemed most appropriate via
@option{-opencl_options} to obtain the best performance for the OpenCL
accelerated code.
Typical usage to use the fastest OpenCL device involve the following steps.
Run the command:
@example
ffmpeg -opencl_bench
@end example
Note down the platform ID (@var{pidx}) and device ID (@var{didx}) of the first
i.e. fastest device in the list.
Select the platform and device using the command:
@example
ffmpeg -opencl_options platform_idx=@var{pidx}:device_idx=@var{didx} ...
@end example
@item -opencl_options options (@emph{global})
Set OpenCL environment options. This option is only available when