Encoding not producing Target Size output

[craigg]

using CCE 2.50 (SP) to encode an avs script using the Rob Shot method (normal usage tried as well) doesn't encode using multipass vbr to the correct target size.

the source i'm trying to encode is 144960 frames long (1:40:46) and i'm trying to encode it @ 5775kbps, which in the long run should produce a mpv of about 4gb. instead its producing a mpv of only 2.42gb. The quality of the video is pretty good considering the source (reencoding from a divx compressed avi), but i'd definately say that the extra bitrate sould be able to be used.

also when passing the output mpv into tmpgenc it only sees it as 35mins long (even though the film isn't truncated at all and plays fine).

anyone with any ideas?

Ta :)

Craigg

[RB]

Originally posted by craigg
(reencoding from a divx compressed avi)
So the source is already fairly "soft" and easy to encode. MPEG2 just cannot get below a quantization of 1.0 (best quality posible), the fact that your output is smaller than expected suggests that less than the bitrate you specified is enough to achive this.
Originally posted by craigg

also when passing the output mpv into tmpgenc it only sees it as 35mins long (even though the film isn't truncated at all and plays fine).

That's normal because it's VBR. TMPEG just makes an educated guess based on the file size and the assumption that it's CBR.

[drob]

Actually I came across several occurrences where there was some minor error with the AVI that CCE could encode easily, and TMPG stop recognizing beyond the corrupted frame, or it could be VBR sound that is braking the situation, use virtualdub or mod, and when you open the file click ok in virtualdub or yes in mod, then select direct stream both for video and audio and save the file as an AVI, when you play the file it would be out of sync, but on encoding it using TMPG it would be ok.

[craigg]

ahh, i suppose that makes sense. vbr encoding in cce is based then on using available bitrate when its required, and so if its not required the output file size would be smaller than expected. its just strange because it will still encode as CBR to the correct size, probably because its forced?

anyway, ta 4ur replys :)

Craigg

[Matthew]

I've re-encoded quite a lot of avis, and this has happened to me a few times too. Although that's a pretty large case of undersizing.

[auenf]

Originally posted by craigg
its just strange because it will still encode as CBR to the correct size, probably because its forced?

thats the whole point of CBR, it maintains the specified bitrate completely throughout the file, even if it has to pad it.

Enf...