Loosing Overall Bitrate in Direct Copy Mode both in Virtualdub and Avidemux

[DBCOOPER1990]

Hi,

I have Video 8 captures in AVI container that I captured via the iLink port of my Sony TVR345 Handycam. I used WinDV for the captures, type 2 avi vids+auds. I would like to perform some minor edits on the masters but when I use the Direct Copy Modes, be it in Avidemux or Virtualdub, both for video and audio, I am loosing a small amount of bitrate. I have just cut 3 seconds of the original and added a 1.5 second section of captured footage to the video, that was captured the exact same way with WinDV. Same format, same everything. The small 1.5 second section has a little higher bitrate, around 31000 kb/sec.

My question is, if these modes are supposed to be direct copies, whats with the bitrate difference? The overall bitrate goes from 30.0 mbits (30.011 kb/sec) down to 29.8 (29.831 kb/sec) despite amending a 1.5 second higher bitrate section. Mediainfo shows the video and audio bitrates for the original and edit as identical 24.4 mb/s and 1024 kb/sec, respectively. The copy mode takes only 6-7 minutes to complete the edit for an around 50 minute video. So I can assume no decoding re-encoding is taking place. I have attached the comparisons.

[jagabo]

Different programs use different padding when muxing. The video and audio streams themselves are unchanged.