There's a TV channel, broadcasting over IPADSL, I need to watch for 2 hours each saturday night.
For many reasons, I can't access it from my new place.

At my office, I have that channel available and a synology NAS with a ARM CPU.
I can VPN that network and access the IPADSL stream.

Thing is, the max upload speed at said office is 115KB/s.

So I need to transcode the stream in realtime and access it from my home.

I've done some testing, transcoding in realtime is possible and the result is more than enough for my needs. I need to transcode the video to around 800kb/s sound included and try to keep sound bitrate at 192kb/s if possible since sound is more important than image in that case.

The testing has been done with fairly low end computer by today's standards, using VLC transcoding/broadcasting.
But I can't use that comp as a longterm solution.

Since I have full access to the nas, the idea is that I use it. But its computing power is far below that of the test comp I used obviously.

Hence the need for help in finding the best set of options to optimize transcoding speed.

Source stats reported by ffmpeg (1 minute sample):
Code:
Duration: 00:00:59.21, start: 13060.597889, bitrate: 3549 kb/s
  Program 1
    Stream #0.0[0x44]: Video: mpeg2video (Main), yuv420p, 720x576 [PAR  64:45 DAR 16:9], 3100 kb/s, 26.89 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0.1[0x45](fra): Audio: mp2, 48000 Hz, stereo, s16, 192 kb/s
With FFMPEG default settings, I get 7-8 FPS processing speed. When I first got that number, I was quite surprised as I thought I would get a much lower "score".

Stats from media for the test sample result:
Code:
General
Complete name                  : \\192.168.0.33\public\test.avi
Format                         : AVI
Format/Info                    : Audio Video Interleave
File size                      : 1.48 MiB
Duration                       : 18s 80ms
Overall bit rate               : 687 Kbps
Writing application            : Lavf52.108.0

Video
ID                             : 0
Format                         : MPEG-4 Visual
Format profile                 : Simple@L1
Format settings, BVOP          : No
Format settings, QPel          : No
Format settings, GMC           : No warppoints
Format settings, Matrix        : Default (H.263)
Codec ID                       : FMP4
Duration                       : 18s 80ms
Bit rate                       : 484 Kbps
Width                          : 720 pixels
Height                         : 576 pixels
Display aspect ratio           : 16:9
Frame rate                     : 25.000 fps
Standard                       : PAL
Color space                    : YUV
Chroma subsampling             : 4:2:0
Bit depth                      : 8 bits
Scan type                      : Progressive
Compression mode               : Lossy
Bits/(Pixel*Frame)             : 0.047
Stream size                    : 1.04 MiB (71%)
Writing library                : Lavc52.120.0

Audio
ID                             : 1
Format                         : MPEG Audio
Format version                 : Version 1
Format profile                 : Layer 2
Codec ID                       : 50
Duration                       : 17s 472ms
Bit rate mode                  : Constant
Bit rate                       : 192 Kbps
Channel(s)                     : 2 channels
Sampling rate                  : 48.0 KHz
Compression mode               : Lossy
Stream size                    : 410 KiB (27%)
Alignment                      : Aligned on interleaves
Interleave, duration           : 25 ms (0.62 video frame)
Interleave, preload duration   : 528 ms
ffmpeg -formats result:
Code:
ffmpeg version UNKNOWN, Copyright (c) 2000-2011 the FFmpeg developers
  built on Sep  4 2011 02:28:29 with gcc 4.2.1
  configuration: --arch=arm --target-os=linux  --cross-prefix=/usr/local/arm-none-linux-gnueabi/bin/arm-none-linux-gnueabi-  --enable-cross-compile --enable-optimizations --disable-yasm  --disable-altivec --enable-pic --enable-shared --disable-static  --disable-swscale-alpha --disable-ffserver --disable-ffplay  --enable-libmp3lame
  libavutil    50. 40. 1 / 50. 40. 1
  libavcodec   52.120. 0 / 52.120. 0
  libavformat  52.108. 0 / 52.108. 0
  libavdevice  52.  4. 0 / 52.  4. 0
  libavfilter   1. 77. 0 /  1. 77. 0
  libswscale    0. 14. 0 /  0. 14. 0
File formats:
 D. = Demuxing supported
 .E = Muxing supported
 --
  E 3g2             3GP2 format
  E 3gp             3GP format
 D  4xm             4X Technologies format
 D  IFF             IFF format
 D  ISS             Funcom ISS format
 D  MTV             MTV format
 DE RoQ             raw id RoQ format
  E a64             a64 - video for Commodore 64
 D  aac             raw ADTS AAC
 DE ac3             raw AC-3
  E adts            ADTS AAC
 D  aea             MD STUDIO audio
 DE aiff            Audio IFF
 DE alaw            PCM A-law format
 DE amr             3GPP AMR file format
 D  anm             Deluxe Paint Animation
 D  apc             CRYO APC format
 D  ape             Monkey's Audio
 D  applehttp       Apple HTTP Live Streaming format
 DE asf             ASF format
  E asf_stream      ASF format
 DE ass             Advanced SubStation Alpha subtitle format
 DE au              SUN AU format
 DE avi             AVI format
  E avm2            Flash 9 (AVM2) format
 D  avs             AVS format
 D  bethsoftvid     Bethesda Softworks VID format
 D  bfi             Brute Force & Ignorance
 D  bink            Bink
 D  c93             Interplay C93
 D  caf             Apple Core Audio Format
 DE cavsvideo       raw Chinese AVS video
 D  cdg             CD Graphics Format
  E crc             CRC testing format
 DE daud            D-Cinema audio format
 D  dfa             Chronomaster DFA
 DE dirac           raw Dirac
 DE dnxhd           raw DNxHD (SMPTE VC-3)
 D  dsicin          Delphine Software International CIN format
 DE dts             raw DTS
 DE dv              DV video format
 D  dv1394          DV1394 A/V grab
  E dvd             MPEG-2 PS format (DVD VOB)
 D  dxa             DXA
 D  ea              Electronic Arts Multimedia Format
 D  ea_cdata        Electronic Arts cdata
 DE eac3            raw E-AC-3
 DE f32be           PCM 32 bit floating-point big-endian format
 DE f32le           PCM 32 bit floating-point little-endian format
 DE f64be           PCM 64 bit floating-point big-endian format
 DE f64le           PCM 64 bit floating-point little-endian format
 D  fbdev           Linux framebuffer
 DE ffm             FFM (FFserver live feed) format
 DE ffmetadata      FFmpeg metadata in text format
 D  film_cpk        Sega FILM/CPK format
 DE filmstrip       Adobe Filmstrip
 DE flac            raw FLAC
 D  flic            FLI/FLC/FLX animation format
 DE flv             FLV format
  E framecrc        framecrc testing format
  E framemd5        Per-frame MD5 testing format
 DE g722            raw G.722
  E gif             GIF Animation
 D  gsm             raw GSM
 DE gxf             GXF format
 DE h261            raw H.261
 DE h263            raw H.263
 DE h264            raw H.264 video format
 D  idcin           id Cinematic format
 DE image2          image2 sequence
 DE image2pipe      piped image2 sequence
 D  ingenient       raw Ingenient MJPEG
 D  ipmovie         Interplay MVE format
  E ipod            iPod H.264 MP4 format
 D  iv8             A format generated by IndigoVision 8000 video server
 DE ivf             On2 IVF
 D  jv              Bitmap Brothers JV
 D  lmlm4           lmlm4 raw format
 D  lxf             VR native stream format (LXF)
 DE m4v             raw MPEG-4 video format
  E matroska        Matroska file format
 D  matroska,webm   Matroska/WebM file format
  E md5             MD5 testing format
 DE microdvd        MicroDVD subtitle format
 DE mjpeg           raw MJPEG video
 DE mlp             raw MLP
 D  mm              American Laser Games MM format
 DE mmf             Yamaha SMAF
  E mov             MOV format
 D  mov,mp4,m4a,3gp,3g2,mj2 QuickTime/MPEG-4/Motion JPEG 2000 format
  E mp2             MPEG audio layer 2
 DE mp3             MPEG audio layer 3
  E mp4             MP4 format
 D  mpc             Musepack
 D  mpc8            Musepack SV8
 DE mpeg            MPEG-1 System format
  E mpeg1video      raw MPEG-1 video
  E mpeg2video      raw MPEG-2 video
 DE mpegts          MPEG-2 transport stream format
 D  mpegtsraw       MPEG-2 raw transport stream format
 D  mpegvideo       raw MPEG video
  E mpjpeg          MIME multipart JPEG format
 D  msnwctcp        MSN TCP Webcam stream
 DE mulaw           PCM mu-law format
 D  mvi             Motion Pixels MVI format
 DE mxf             Material eXchange Format
  E mxf_d10         Material eXchange Format, D-10 Mapping
 D  mxg             MxPEG clip file format
 D  nc              NC camera feed format
 D  nsv             Nullsoft Streaming Video
  E null            raw null video format
 DE nut             NUT format
 D  nuv             NuppelVideo format
 DE ogg             Ogg
 D  oma             Sony OpenMG audio
 DE oss             Open Sound System playback
 D  pmp             Playstation Portable PMP format
  E psp             PSP MP4 format
 D  psxstr          Sony Playstation STR format
 D  pva             TechnoTrend PVA file and stream format
 D  qcp             QCP format
 D  r3d             REDCODE R3D format
 DE rawvideo        raw video format
  E rcv             VC-1 test bitstream
 D  rl2             RL2 format
 DE rm              RealMedia format
 D  rpl             RPL/ARMovie format
 DE rso             Lego Mindstorms RSO format
 DE rtp             RTP output format
 DE rtsp            RTSP output format
 DE s16be           PCM signed 16 bit big-endian format
 DE s16le           PCM signed 16 bit little-endian format
 DE s24be           PCM signed 24 bit big-endian format
 DE s24le           PCM signed 24 bit little-endian format
 DE s32be           PCM signed 32 bit big-endian format
 DE s32le           PCM signed 32 bit little-endian format
 DE s8              PCM signed 8 bit format
 DE sap             SAP output format
 D  sdp             SDP
 D  shn             raw Shorten
 D  siff            Beam Software SIFF
 D  smk             Smacker video
 D  sol             Sierra SOL format
 DE sox             SoX native format
 DE spdif           IEC 61937 (used on S/PDIF - IEC958)
 DE srt             SubRip subtitle format
  E svcd            MPEG-2 PS format (VOB)
 DE swf             Flash format
 D  thp             THP
 D  tiertexseq      Tiertex Limited SEQ format
 D  tmv             8088flex TMV
 DE truehd          raw TrueHD
 D  tta             True Audio
 D  tty             Tele-typewriter
 D  txd             Renderware TeXture Dictionary
 DE u16be           PCM unsigned 16 bit big-endian format
 DE u16le           PCM unsigned 16 bit little-endian format
 DE u24be           PCM unsigned 24 bit big-endian format
 DE u24le           PCM unsigned 24 bit little-endian format
 DE u32be           PCM unsigned 32 bit big-endian format
 DE u32le           PCM unsigned 32 bit little-endian format
 DE u8              PCM unsigned 8 bit format
 D  vc1             raw VC-1
 D  vc1test         VC-1 test bitstream format
  E vcd             MPEG-1 System format (VCD)
 D  video4linux     Video4Linux device grab
 D  video4linux2    Video4Linux2 device grab
 D  vmd             Sierra VMD format
  E vob             MPEG-2 PS format (VOB)
 DE voc             Creative Voice file format
 D  vqf             Nippon Telegraph and Telephone Corporation (NTT) TwinVQ
 D  w64             Sony Wave64 format
 DE wav             WAV format
 D  wc3movie        Wing Commander III movie format
  E webm            WebM file format
 D  wsaud           Westwood Studios audio format
 D  wsvqa           Westwood Studios VQA format
 D  wtv             Windows Television (WTV)
 D  wv              WavPack
 D  xa              Maxis XA File Format
 D  xwma            Microsoft xWMA
 D  yop             Psygnosis YOP Format
 DE yuv4mpegpipe    YUV4MPEG pipe format

I tried halving height and width, setting 15FPS for the output and many codecs, but never really got over 9FPS... only when I divided height and width by 4 and got 14 FPS. But it's not very watchable anymore.

I can accept halving height and width
I can accept pixelisation
I can accept going to 20FPS for the output
If I have no other option I can accept going to 128kb/s for the audio although transcoding it would impact processing speed I guess.

The resulting file must be 800kb/s max and I need transcoding settings that allow for maximum speed. I know that maybe it's impossible to cope with all those conditions on such a slow system (DS109) but I wish to try.

Thanks for reading Even more if you can and do help