[FFmpeg-user] Benchmarking with ffmpeg - What are the parameters meaning?

[Andy Sheen]

David Wagner wrote on Mon 10 Sep at 23:46 UK time
> Am 10.09.2012 21:18, schrieb Andy Sheen:
>> Roger Pack wrote on Mon Sep 10 2012 19:43:18 GMT+0100 (GMT Daylight Time)
>>>>> What is meant by the fps? Is it the (averaged) speed at which
>>>>> the frames are processed?
>>>> No, not averaged but current.
>>> I thought fps was average? If now, how much of a window does it take
>>> into
>>> consideration do you know?
>> Definitely averaged..... I often skip a few minutes of streams when
>> recoding and the value slowly climbs - starting at 0.
> Can you tell me why this means that it is the average speed and not the
> real speed at which the frames are processed. I'm not sure if I
> understand the assumption in your example.

If I skip 5 minutes of video at the start of an encode (with -ss
0:05:00) the processor is searching for the I frame closest to 5mins in.
I think it does this by decoding the stream as fast as it can - lets say
it takes 1 minute to reach there.

During this 1 minute, the fps = 0, after 1 minute, the fps gradually
climbs and heads asymptotically (with a little under/overshoot) to the
final fps value. I.e. after it has encoded 10 secs of video, fps may be
4. After 10 minutes of encoding, it may have settled to 30fps.

If it were measuring "current" encode rate, it would immediately jump to
30fps as soon as it starts encoding.

I think the maths is simple number-encoded-frames/secs-since-start. That
is, after all, the definition of fps for encode rate (you encode 100000
frames - it takes you 10000 secs, fps = 10).

>>> -r
>> Andy
>>
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