H.264 file size?

[lordsmurf]

I just wanted to check up on something.

I have a video that is 1:55 (one hour, 55 minutes) long.
I've encoded it as H.264 using x264 through VirtualDub (x264vfw), 640x480, with single-pass ABR, 1000k bitrate.
The file size is 855MB.

Is this normal?
Slightly higher, slightly lower?
Too high?

I don't often work with such long streams as H.264, wanted to check against somebody else.
This is intended to be high-quality streaming content, via Adobe Flash 10.

Source video is 720x480 DVD, made from a clearly lower-resolution source (mix of VHS, Betacam, others)
I'm almost wondering if the bitrate could be lower.

[minidv2dvd]

any audio? if so what bitrate? but, it looks to be in the correct ballpark. i don't have much luck with rates any smaller than that. just not enough detail to even be good for decent streaming material.

[poisondeathray]

It should be ~822.5mb (no audio) for 1000kb/s in .mp4 container, avi overhead is slightly higher (and I am uncertain if you can use .avi for streaming flash, so you might have to to put into .mp4 later if you are using vdub)

1pass abr won't give you as good results as using crf or 2-pass mode

If you are using the default x264 vfw settings, just beware they are set for low quality, so if you intend on "high quality streaming content" you might want to adjust them a bit.

Consider bumping up the reference frames from 1 to at least 3, and using a few b-frames should almost mandatory (IMO) for streaming content (it is set to zero at default)

[jagabo]

bitrate * running time = file size

1000 kbps * 115 minutes * 60 seconds per minute / 8 bits per byte = 862500 kbytes ~= 862 MB

Could the bitrate be lower? Use constant quality (CRF or CQP) encoding. Pick the quality you want. The file will use whatever bitrate is necessary to achieve that quality.

[poisondeathray]

jagabo, your math is correct, but I think our #'s are different because of binary vs. SI Decimal definition of kbytes?

http://www.dewassoc.com/kbase/hard_drives/binary_v_decimal_measurement.htm

[jagabo]

Yes, that's the difference between our calculations. I just wanted to show the OP the general calculation.