How doi i create a smaller MPEG file

Finatic13 wrote on 7/17/2002, 3:18 AM
Hi All
I have an edited video thats 80 minutes long, im creating a seperate NTSC video stream for this but its coming out at 3.65gig, which is too big for the project im working with.

I first made the file using VBR at 6,000 to 8,000, i then made the file using a CBR of 6,000 and it was the same size as the above.

Does the bit rate affect the file size even when creating an NTSC elementry seperate stream??
should i go lower maybe 5000?? ts taking meapproximatly 10 hours to render the file so a it of info before hand would be appreciated

Im wanting a finished file of about 3gig in size.

thanks for the help
regards
simon



Comments

Chienworks wrote on 7/17/2002, 7:52 AM
Does the bitrate affect the size? Yes. The bitrate defines the size of the output file.
dsanders wrote on 7/17/2002, 9:59 AM
I thought that I remember reading that in VV 3.0, the mpeg bit rate settings don't quite work right. This is one of the things fixed in revision VV 3.0c. If you don't have the "c" version, I would suggest that you download it.

Also, you might want to select a five minute portion of the video and just render it using the different settings. That might give you some idea of the final quality/file size.
vonhosen wrote on 7/17/2002, 11:06 AM
Use this formula to work out what bitrate you can use safely for your 4.7Gb DVD general media. Just adjust the audio amount to what you are going to use in project. 1600Kbs for PCM and whatever you have chosen for compressed audio should you have that.

The safe, useable size for Video and Audio is 3.6 gigs. As shown below in the formula:

DVD: 36096 Mbits of safe useable space
Space for AC3 audio (at 192 Kbit/s)= (number of seconds in your video*192)/1024
e.g. audio for 2 hours, (7200*192)/1024 = 1350 Mbits
Remaining space can be allocated for video, 36096-1350 = 34746 Mbits
For 2 hour project: video data rate = remaining space/number of seconds in your video
e.g. 34746/7200 = 4.825 Mbit/s
If using PCM audio, substitute 1600 in place of 192 in the audio calculation.

Since it’s easier to calculate the minutes, rather than the seconds, here’s the formula:

For AC3 audio:

(36096-(((Length of Video in Minutes*60)*192)/1024))/(Length of Video in Minutes*60)

For PCM audio:

(36096-(((Length of Video in Minutes*60)*1600)/1024))/(Length of Video in Minutes*60)


vonhosen wrote on 7/17/2002, 11:43 AM
Another quicker recipe you can use is this.

Remember the number 600.
Divide 600 by the number of minutes: e.g. 600/82=7.3
This is the bit rate in Mb/s for video and audio combined.
Subtract the audio bit rate: for uncompressed audio 1.6Mb/s, for compressed audio 0.2Mb/s*.
With DVDit PE you can use compressed Dolby Digital (AC3) audio: 7.3-0.2=7.1.
You could encode the 82 minute video with 7.1Mb/s to make it fit on a DVD-R.

For shorter projects be aware that the maximum bit rate allowed on a DVD is 9.8Mb/s for audio and video. Meaning that you can't have a 10 minute clip with 59.8Mb/s.

(*It depends on the bit rate you select for the AC3, but 192Kb/s (~0.2Mb/s) is a normal setting.)