[FFmpeg-user] Request for advise on performance - transcoding on the fly

[Charu Palkar]

Hi,

I am new to the forum and would like guidance.

System :
     Server : Rackable
     CPU :  AMD Opteron  (2GHZ) Dual CPU
     RAM : 2 Gb
     Disk  : SATA  ( 250GB x 4 disks )  -  3 disks configured as RAID0  (3Ware)
     Network :  1 Gig
     OS : Slackware - 13.1

Command :
      ffmpeg -benchmark -i 
/mnt/samba/share/test/Baraka.1992.BRrip.H264.AAC.ITS-ALI.mp4 -threads 4 -target 
ntsc-dvd -aspect 16:9 test.mpg

NOTES :
      Only one CPU has 90% (sys + user),  others 4% (sys + user),  no wait on 
I/O
      There is no swapping, initial page faults is 11 and remains constant for 
the entire time
      Both files input and output are located on the RAID partition
      The time it takes to transcode is 20% higher than the run-time of the 
media file
      Nothing else is running on the server
      ffmpeg - Built with ARCH=x86_64  CPU=opteron

QUESTIONS :
      Q : What else can I do to speed up the transcoding  to take less time than 
run-time of media file ?
                + To use for on-the-fly transcode with a media server.

      Background : Installed media server  'serviio' and transcoding 
on-the-fly-enabled. The following command is invoked.

                          ffmpeg -i 
/mnt/samba/share/test/Baraka.1992.BRrip.H264.AAC.ITS-ALI.mp4 -y -threads 4 
-vcodec mpeg2video 
                                    -sameq -r 23.976 -g 15 -copyts -acodec ac3 
-ab 192k -ac 6 -map 0:0 -map 0:1 -sn -f mpegts
                                    
 /mnt/samba/trans_tmp/Serviio/transcoding-temp-2-MPEG2TS.stf

                          CPU Usage is 60% per core and no wait on I/O, 
swapping.

                           Viewing using WDTV Live  streaming stops after 31 
secs consistently
                           Viewing using  XMBC on WinXP  stream starts buffering 
after  7 mins or 3 mins of play, takes about 8 to 10 seconds to catch up
                           Cabled network 100 MB connection on WinXP the network 
usage varies between  7% to 50%

       Q : What can be done to make transcoding on-the-fly continuous ?

Any and all help is greatly appreciated.

Thanx

Charu Palkar
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