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Ubuntu - Video - ffmpeg - Hardware Acceleration using GPU - AMD GPU - Benchmark

Null muxer

A simple way to benchmark decoding is to use the null muxer:

ffmpeg -i input -f null -

Linux and macOS users can add the time command:

time ffmpeg -i input -f null -

returns:

[...]
real    0m5.343s
user    0m20.290s
sys     0m0.230s

NOTE: See man time for more info.

The -benchmark option can be added to output CPU time and maximum memory consumption:

time ffmpeg -i input -benchmark -f null -

returns:

[...]
bench: utime=7.314s
bench: maxrss=72280kB

ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -hwaccel_output_format vaapi -i a.mp4 -c:v hevc_vaapi -q:v 28 -f null - -benchmark

returns:

...
bench: utime=0.156s stime=0.195s rtime=3.003s
bench: maxrss=358944kB

NOTE: maxrss indicates the maximum RAM used during the ffmpeg execution.

utime: user time.
- utime is the sum of processing time across all threads. Since they may operate in parallel, utime can exceed rtime.
stime: system time.
rtime: real time.

The following parts of the command force a null file and tells ffmpeg to benchmark.

-f null - -benchmark