[FFmpeg-user] ffmpeg: parallel encoding and cpu utilization.

[theairkit]

Hi.
First of all, sorry for my probably bad english (i`m russian).

I test scheme for online conferences (using bmdcapture, ffmpeg,  
nginx-rtmp).

So, i used ffmpeg to parallel encode to some formats at the same time.

For clean test, i record rawvideo to file:

bmdcapture -M 2 -A 2 -V 3 -m 8 -F nut -f ./rawvideo

Then, i run command:

cat ./rawvideo | \
/usr/bin/ffmpeg -re -i - \
-vcodec libx264 -acodec libfdk_aac -b:a 128k -ar 44100 -y -f flv  
rtmp://$url_1080p \
-vcodec libx264 -acodec libfdk_aac -b:a 128k -ar 44100 -s 1280x720 -y -f  
flv rtmp://$url_720p \
-vcodec libx264 -acodec libfdk_aac -b:a 128k -ar 44100 -s 720x404 -y -f  
flv rtmp://$url_pal \
-vcodec libx264 -acodec libfdk_aac -b:a 128k -ar 44100 -s 960x640   
-pix_fmt yuv420p -y -f flv rtmp://$url_hls

When it running, i see 'top -H' (fragment):

15672 root      20   0 1852m 1.2g 3988 R   94 15.1   0:52.96 ffmpeg

That is, one thread utilizes up to 100% of one core.
Other threads utilizes much less (each - about 20%).

So, result video (i see in from web-page as flash, or as HLS from ipad) -  
is show very slowly, and some time not load.

I suppose, that this thread is not enough CPU frequency, now its: 2 x  
Intel(R) Xeon(R) CPU E5520 @ 2.27GHz

I trying to ran this command on other CPU (Intel(R) Xeon(R) CPU E5645  @  
2.40GHz), it looked the same...

So, my questions is:
1. Will help me increasing cpu frequency (if i use corei7 with frequency >  
3GHz)?
2. Why this silngle ffmpeg thread uses so much single CPU (i would like to  
understand this...)?
3. Do you have any recommendations about hardware for using this scheme;

Thanks in advance!


Info about host and ffmpeg:

ffmpeg version 1.2 Copyright (c) 2000-2013 the FFmpeg developers
   built on Apr 16 2013 13:46:11 with gcc 4.4.3 (Ubuntu 4.4.3-4ubuntu5)
   configuration: --prefix=/usr --enable-gpl --enable-nonfree  
--disable-yasm --enable-libx264 --enable-libmp3lame --enable-libfdk-aac
   libavutil      52. 18.100 / 52. 18.100
   libavcodec     54. 92.100 / 54. 92.100
   libavformat    54. 63.104 / 54. 63.104
   libavdevice    54.  3.103 / 54.  3.103
   libavfilter     3. 42.103 /  3. 42.103
   libswscale      2.  2.100 /  2.  2.100
   libswresample   0. 17.102 /  0. 17.102
   libpostproc    52.  2.100 / 52.  2.100

Host:
Distributor ID:	Ubuntu
Description:	Ubuntu 10.04.4 LTS
Release:	10.04
Codename:	lucid
Linux 2.6.32-41-server #94-Ubuntu SMP Fri Jul 6 18:15:07 UTC 2012 x86_64  
GNU/Linux
2 x Intel(R) Xeon(R) CPU           E5520  @ 2.27GHz
8GB RAM

-- 
theairkit.