Encoding to a target size

[videoip]

Is there any way I can encode a video to get a predictable file size? I try to calculate size=length*(audiobitrate + videobitrate), but I always get a file a lot larger than calculated.
Could you at least tell me why this is? I´ve tried different muxers and codecs and that makes the file size vary, but I always find this quite unpredictable.

[The DJ]

It's because next to video and audio, there is a lot more in a file. This is called the muxing overhead. various fileformats have various amounts of overhead. Predicting this exactly is almost impossible. You just need to make an educated guess.

[videoip]

Thanks for the info. Now, how do I "educate" myself in this? I´m trying to predict the size of a h264 video on TS. Do muxer overheads weigh less on longer files? Please tell me where I can read more on any of this.

[markfm]

mpeg ts chops things up into little 188 byte packets. The norm in VLC is to then put 7 of these packets together into one Ethernet packet (since 7x188 < 1500 bytes, a "normal" MTU)

Do a search for ISO 13818-1 on the Web -- it gives you the definition of what is in a transport stream (a bit of a slog, admittedly).

Alternately, take a look at:
http://www.leitch.com/resources/tutoria ... ystems.pdf

see page 47 of the document, which gives you a glimpse of the kinds of TS packets.