AMV file size

[JaddziaDax]

this is the compression method i use...
also cleaning up your video with AVISynth can also help reduce your file size.

[Scintilla]

use the system calculater and find what you want and see if it works. Take a 4 minute song for example. 4x60 = 240seconds. so you want a 65mb file. That is 65000KB. 65000/240 = 270kb/second. (THIS IS JUST YOUR AVERAGE BITRATE.

No, that's your average BYTErate. You forgot to multiply by 8, which gives an average bitrate of 2160 kbps -- and that's still without subtracting out the bitrate required for the audio.

[Gepetto]

That's a generalized way to calculate the video bitrate. But it also depends on what's on the screen (not just how many effects or flashes or whatnot). Remember that video is simply a sequence of images, and a 320x240 black image takes up a lot less space than a 1024x768 screenshot from an explosion scene in FF XII.

[EvaFan]

270<b>kb/second</b>.

kthxbai

[Willen]

270<b>kb/second</b>.

No, that's your average BYTErate. You forgot to multiply by 8, which gives an average bitrate of 2160 kbps -- and that's still without subtracting out the bitrate required for the audio.

kthxbai

The reason for the confusion is little b = bit, big B = BYTE (8 bits).

So, average BIT rate = 2160 kbps. Average BYTE rate = 270 kBps. Capital letters make a big difference here.

so you want a 65mb file.

Same here. I know you mean megabyte not millibit (or millibyte? megabit?), because what would a millibit (or millibyte) be?

Resources:
http://en.wikipedia.org/wiki/Byte
http://ts.nist.gov/ts/htdocs/200/202/metrsty3.htm

Anyways, back to the topic, Eva-Fan's method is essentially correct, but like Scintilla mentioned, make sure you factor the audio out when calculating the video bitrate or you'll end up with a filesize bigger than you intended. Depending on how the audio is compressed, this could be 4 or more MBs of additional data (assuming you remembered to compress the audio, if not, you are looking at 40+ MBs for a 4 minute song). So your 65 MB target AMV is actually a 69+ MB file with the audio muxed.

Going back to that target 65 MB, you want to subtract the audio filesize first. Let's say 5 MB for the MP3 audio. So that means 60 MB for the video. That equals approximately 60000 kB (http://en.wikipedia.org/wiki/Kilobyte). 60000 kB/240 s = 250 kBps = 2000 kbps. And yes, this is a generalized way to calculate as Gepetto says. Content, video resolution, and frame rate will have an effect on filesize also. Ultimately, you have to carefully watch the compressed video to determine if the bitrate is too low or if the loss in visual quality is acceptable.

For example, my ASIB(SA) video is a (mostly) slow paced romance video, but has the same (actually higher) bitrate as my RFM video which is an action AMV. This is due partly to how I processed and edited each video and the conditions of each source. For ASIB(SA), it uses KOR which being an older anime is fairly "dirty" footage-wise with lots of grain and scratches. Unfortunately, I didn't pre-process the footage before sticking it into my editor so I had to do it in post. Which, because of the massive amounts of fade transitions I used made it harder to properly clean up (and compress). If you watch it, there are portions where blocking becomes apparent. And this is a 65 MB video file (plus 6 MB audio = 71 MB total) for a 4:37 640x480 slow-paced video! The first pass video data ended up being 89 MB (plus audio 96MB). And while still having blocking (due to the fades), is cleaner overall.

Now RFM is totally different. As typical of action videos, you have fast cuts, lots of motion, white flashes, and tons of stuff going on in each scene. FLCL has one big advantage over KOR: it was animated using digital processes and is a much cleaner source because of it. So clean in comparison, I forgot to do any processing on the video footage, pre- or post-. The second pass distro copy has a 35 MB video file (and 3.5 MB audio, 39 MB total) for a 2:35 640x480 AMV. The first pass copy is a 53 MB video file (57 MB total), and honestly, the differences in video quality are slight. I probably could have pushed the average bitrate lower, but I erred on the side of caution. So I did the first (full) pass, then the second (70%) and called it a day. Unlike ASIB(SA), where I think I did 4 encodes total before settling on the one on local now. Of course, the fact that RFM is a 23.976 fps video helps the filesize also (less frames to encode), compared to ASIB(SA)'s 29.97 fps.

I'm not too thrilled that ASIB(SA) is a 71 MB file for a 4:37 video since it is a slow romance video (I'd actually like it closer to 50 or 60 MB). Because RFM is an action video, being 39 MB for a 2:35 video I'm OK with.

[jubjub2]

Kids. Stay in school.

You WILL use math.



*bookmarks*

[Willen]

Kids. Stay in school.

You WILL use math.



*bookmarks*

Oh crap. That was MATH that I used? At least I didn't also use kilo = 1024 or mega = 1,048,576

[EvaFan]

I think willen just made this thread stickyable for anyone who needs help on filesizes or bitrate, dunno still alot more stuff to cover that affects size and qaulity.

[BasharOfTheAges]

All hail the power of base 2 expansion!

[Castor Troy]

2 + 2 = 5