AC3 and Compressor bitrates?

[adamthole]

Is there an equation, or anyway to tell, what my average bit rate can be in compressor for X length video when the audio I use is .ac3?

When you add your own templates, it gives you an estimate of how many minutes will fit onto a DVD, but that estimate is using .aiff for the audio file.

Any idea?

Also does .ac3 audio work with all dvd players/sound systems?

[Frobozz]

Give Mr. Bitbudget a try
http://www.planfilmberlin.com/mrbb/mrbitbudget0.5bX.sit

.ac3 is universally supported on DVD players which also convert the sound to standard analog stereo through the line output or RF cable.

[WiseWeasel]

The equation is rather simple. If you're using single-layered DVD-R media, then you have 4,700,000,000 bytes to fill = 4,589,843 kbytes = 4482 MB = 4.37 GB. If you use 192kbit/sec AC3 (common bitrate for stereo audio), if X (length of film) = 2hrs = 7200 seconds * 192 kbit/sec = 1,382,400 kbits. or 172,800 kbytes = 168.75 MB, leaving 4313.25 MB for video (assuming you have a single audio track. If the video is 7200 seconds, that means you have to have the bitrate below 0.599 MB/sec, or 4.79 Mbit/sec (4313.25 MB / 7200 seconds * 8 bits/byte). You might want to leave a little bit of extra space for the DVD menu and such, so if you want to make it 100 MB smaller (should be enough space for a decent motion menu), 4213.25 MB / 7200 seconds * 8 bits/byte = 4.68 Mbit/sec. Compressor's VBR (Variable Bit Rate) encoder isn't exactly accurate (and depends on how much complexity and motion is in the video you're using), so it may take a bit of trial and error before you find a setting that gives you the exact size you want.

[Hans de Bijl]

http://home.wanadoo.nl/hansdebijl/pages/FCP%20to%20DVDSP.html

[willrob]

BitrateCalc appeared on versiontracker a couple of days after this thread started. It seems we don't all have to be math majors.

[deadsierra]

BitrateCalc appeared on versiontracker a couple of days after this thread started. It seems we don't all have to be math majors.

Or have completed grade six math.

[adamthole]

Thanks for the Bitrate Calculator, it works great!

Man, I'm gald I didn't have your sixth grade teacher!

It's not the math that I have a problem with, it is remembering all the bits bytes and whatnots.