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

[David Wagner]

Am 11.09.2012 00:53, schrieb 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.
Ok, now I don't know what current encode rate could be? The momentary 
output?

In the beginning I have some lines like that.

frame=  113 fps=0.0 q=39.0 size=      40kB time=00:00:02.13 bitrate= 
154.1kbits/s

Is this 0 because also 0 seconds have passed? And the calculation in the 
first second would be 113/0 ?

> 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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