how exactly does bitrate calculation work?

[4th alphabet]

hi, i recently tried fitting an 89min movie onto a single disc MPEG1 VCD. the bitrate calculation on DVD2SVCD for 89mins on an 80min CD-R is 1023kbit/sec. so i set the max, min, min avg, and max avg all to 1000kbit/sec. am i understanding this correctly? cos the result i got were 2 files, one 79min long and the other was 10min.

does the estimated bitrate calculation include the audio bitrate as well? like in the example above, 1023kbit/sec would mean the total of the video AND audio bitrates. so if my audio bitrate was 192kbit, would i have to set the max, min, min avg, and max avg to 1023-192 = 831kbit?

i always assumed the bitrate did not include audio because for a standard VCD of 1150kbit/sec video and 224kbit/sec audio the total bitrate would be 1374kbit/sec. but according to the bitrate calculation 80mins on an 80min CD-R would use 1161kbit/sec. if this figure was for video alone that would be correct, but if it includes audio as well, it means a standard VCD wouldn't be able to fit 80mins on an 80min CD-R, which it does.

hope i'm making some sense here. i just need help in understanding the bitrate calculation. any guides i could look at?

thanks!

[Labersack]

The shown bitrate in bitrate-tab is only video. You don't have to set all values to 1000kb, because if you do so, the programm can't use it's caculated value and you will do a CBR-encode with 1000kb, no matter what will be the correct bitrate.
Set your max to something higher than 1000 and your min to something lower, don't check the min.avg. box, and D2S will calculate the bitrate by itself. To hit the correct filesize, you should use at least 2Pass VBR or CBR.
But you won't gat an VCD, it will be a XVCD, because VCD has to be 1150kb CBR Video + 224kb Audio, nothing else is allowed.
My player has no problems with a VCD with MPEG1 VBR from 800 to 2000 and Audio from 128 to 224, best you try it with a CD-RW first.

[4th alphabet]

thanks for the reply labersack. i'm still a little confused about something. i hope somebody will be patient enough to explain it to me.

to confirm, the bitrate calculated on the bitrate tab is the max average bitrate the video can have in order to satisfy the parameters we defined, EXCLUDING audio. correct?

On the birate tab, 79mins Use 1 CD size 800 gives me 1147kbit/sec.

i encoded the same movie twice with the following settings. The first time i set all the values in the bitrate tab to 1000kbit/sec and audio at 192kbit/sec and used CBR. I managed to fit a maximum 79mins on the first disc.

The second time i set all values in the bitrate tab to 1150kbit/sec and audio at 224kbit/sec and used CBR. I also managed to fit maximum 79mins on the first disc.

the total average bitrate (video PLUS audio) for the first time was 1192kbit/sec, a little over the calculated 1147, but not much. while the total for the second time was 1374kbit/sec. isn't this over the 1147 bitrate calculation for 79mins on one CD? how come i was still able to fit 79mins on the disc? and shouldn't the first disc be able to hold a little more running time than the other since the bitrate is less?

[Labersack]

The shown bitrate in the tab is only the ESTIMATED rate. What the bitrate realy is, you can see if CCE is being started, because only in this stage DVD2SVCD has the correct duration of the movie.
And yes, if you set all values as you wrote, the second disc should be a little shorter than the first one. Please post the logs of both conversions if you still have them. Without the logs I don't know what happend.