[FFmpeg-user] Strange CPU usage in MPEG2 encoding

[Roberto Ragusa]

On 09/04/2014 12:33 PM, SF wrote:

> Clearly, the following options : 
> 
> -b:v 2300k -maxrate 2500k -bufsize 2500k -muxrate 2500k
> 
> are consuming more than twice CPU power than 
> -maxrate 2500k -bufsize 2500k -muxrate 2500k

What is the resulting bitrate in the second case? Much smaller?

Another explanation could be that if you ask for a very
specific bitrate the encoding process has to encode a frame,
then retry a few times with stronger/weaker quantization to
match the bitrate target. I suppose the code does not
really encode, just estimate used bits, but I would not be
surprised if estimation would be almost as slow as actual
encoding.

I'm not familiar with code internals, so I could be wrong.

-- 
   Roberto Ragusa    mail at robertoragusa.it