seeking help with rtmpdump

[anctop]

Hi,

I've a problem about choosing high quality streams in downloading with rtmpdump.

Currently I'm using a front-end called "RTMPHelper" (on Windows) to download video streams, but the problem is that it can only grab the default "medium" quality.

For example, when I try to get the video from "http://mytv.tvb.com/tc/cat_lifestyle/braingames2/236859", the rtmpsuck console shows :

Processing connect
       app : vipo/_definst_/mp4:vipo/34/6758/675716/000000874154.mp4?ts=1455764386
  flashVer : WIN 19,0,0,185
    swfUrl : http://img.tvb.com/mytv4/swf/supertv_r2-1.swf?1455764376
     tcUrl : rtmpe://wowza.stream.tvb.com:1935/vipo/_definst_/mp4:vipo/34/6758/675716/000000874154.mp4?ts=1455764386
   pageUrl : http://mytv.tvb.com/tc/cat_lifestyle/braingames2/236859
WARNING: Trying different position for server digest!
      live : no
  Playpath : mp4:vipo/34/6758/675716/000000874154.mp4
 Saving as : 2016-02-18_10-59-54_000000874154.flv
WARNING: ignoring too small audio packet: size: 0
INFO: Metadata:
INFO: trackinfo:
INFO:   language                und
INFO:   timescale               90000.00
INFO:   length                  121546800.00
INFO: sampledescription:
INFO:   sampletype              avc1
INFO:   language                und
INFO:   timescale               44100.00
INFO:   length                  59565056.00
INFO: sampledescription:
INFO:   sampletype              mp4a
INFO:   language                und
INFO:   timescale               44100.00
INFO:   length                  59565056.00
INFO: sampledescription:
INFO:   sampletype              mp4a
INFO:   language                und
INFO:   timescale               44100.00
INFO:   length                  59565056.00
INFO: sampledescription:
INFO:   sampletype              mp4a
INFO:   language                und
INFO:   timescale               44100.00
INFO:   length                  59565056.00
INFO: sampledescription:
INFO:   sampletype              mp4a
INFO:   audiochannels           2.00
INFO:   audiosamplerate         44100.00
INFO:   videoframerate          25.00
INFO:   aacaot                  2.00
INFO:   avclevel                31.00
INFO:   avcprofile              77.00
INFO:   audiocodecid            mp4a
INFO:   videocodecid            avc1
INFO:   width                   853.00
INFO:   height                  480.00
INFO:   frameWidth              854.00
INFO:   frameHeight             480.00
INFO:   displayWidth            853.00
INFO:   displayHeight           480.00
INFO:   framerate               25.00
INFO:   moovposition            146678113.00
INFO:   duration                1350.68

and the log file contains a line

rtmpdump -r "rtmpe://wowza.stream.tvb.com:1935/vipo/_definst_/mp4:vipo/34/6758/675716/000000874154.mp4" -a "vipo/_definst_/mp4:vipo/34/6758/675716/000000874154.mp4?ts=1455764386" -f "WIN 19,0,0,185" -W "http://img.tvb.com/mytv4/swf/supertv_r2-1.swf" -p "http://mytv.tvb.com/tc/cat_lifestyle/braingames2/236859" -C S:vipo/34/6758/675716/000000874154.mp4 -C S:1455764386 -C S:33d0b324e6866816d3bccedbdde4cfdf -y "mp4:vipo/34/6758/675716/000000874154.mp4" -o "2016-02-18_10-59-54_000000874154.flv"

Then I switch to high quality (1280x720) and drag the slidebar back to the beginning, the log file contains a further line

rtmpdump -r "rtmpe://wowza.stream.tvb.com:1935/vipo/_definst_/mp4:vipo/34/6758/675716/000000874154.mp4" -a "vipo/_definst_/mp4:vipo/34/6758/675716/000000874154.mp4?ts=1455764728" -f "WIN 19,0,0,185" -W "http://img.tvb.com/mytv4/swf/supertv_r2-1.swf" -p "http://mytv.tvb.com/tc/cat_lifestyle/braingames2/236859" -C S:vipo/34/6758/675716/000000874154.mp4 -C S:1455764728 -C S:7fe63e0fdde31b1886468d24c6c5208e --live -y "mp4:vipo/34/6758/675716/000000874156.mp4?audioindex=0" -o "2016-02-18_11-05-38_000000874156.flv"

and the resultant .flv is incomplete.

I tried to execute the rtmpdump commands directly, but fail

RTMPDump v2.4 GIT-2014-03-02 (Compiled by KSV)
(c) 2010 Andrej Stepanchuk, Howard Chu, The Flvstreamer Team; license: GPL
Connecting ...
WARNING: Trying different position for server digest!
INFO: Connected...
ERROR: RTMP_ReadPacket, failed to read RTMP packet header

Could someone suggest a solution ?

Thanks in advance.