ceiling on bitrate for transport stream?

[alfred]

We are trying to convert a quicktime mpeg 4 file to a mpeg2 transport stream using vlc command line. Given the following parameters
C:\Program Files\VideoLAN\VLC>vlc -I dummy -vvv c:\smaller.mov :sout=#transcode{
vcodec=mp2v,vb=15000,acodec=mpga,ab=192,channels=2}:duplicate{dst=std{access=file
,mux=ts,url="c:\d2.ts"}}
give us a decent quality mpeg2. If we increase the bitrate however,
C:\Program Files\VideoLAN\VLC>vlc -I dummy -vvv c:\smaller.mov :sout=#transcode{
vcodec=mp2v,vb=20000,acodec=mpga,ab=192,channels=2}:duplicate{dst=std{access=file
,mux=ts,url="c:\d2.ts"}}
it results in a lower quality file. Is there anything we can do about it?

[BigBen]

well, 15 Mbit/s is already a lot for a standard sized (eg 640x480) video stream (for instance, a DVD stream is about 6-9 Mbit/s. I wouldn't be surprised if ffmpeg wasn't able to profit from bitrates high like this correctly...

[Alfred]

We are working with HD that starts off at 18300000 bps, at 15 Mbits there is noticable degradation. The highest possible bitrate that VLC outputs is determined by ffmpeg then BigBen?

[BigBen]

I would say so... Not sure ffmpeg encoder is the best fit for HDTV... But I think you will more info on that looking in ffmpeg doc...