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Topic: wasting lots of space when encoding a movie?! (Read 4319 times) previous topic - next topic
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wasting lots of space when encoding a movie?!

hi,

maybe you can help me out with the optimal settings for movie-encoding.

many movies are 60% silent or there is very little noise from the surrounding. shouldn´t the codec go to a very low bitrate here?

when i encode a movie with abr, wich is the current suggestion amongst people that encode movies, the bitrate is kinda forced to encode silent passages at a rather high rate.

i would like to spare up that bitrate for music and action passages, where then i would have enomous headroom.

or am i overseeing something really imoptrant in how audio-encoding works?

regards
/jc

wasting lots of space when encoding a movie?!

Reply #1
Quote
Originally posted by justin_case
hi,

maybe you can help me out with the optimal settings for movie-encoding.

many movies are 60% silent or there is very little noise from the surrounding. shouldn´t the codec go to a very low bitrate here?

when i encode a movie with abr, wich is the current suggestion amongst people that encode movies, the bitrate is kinda forced to encode silent passages at a rather high rate.


a) You can use VBR, which can flex as low as needed.

b) Parts that are digitally silent will be encoded at a very low bitrate. If there is very silent hiss/background noise, the encoder cannot drop the bitrate much, as there is nearly no masking either.

--
GCP

wasting lots of space when encoding a movie?!

Reply #2
so what settings would you suggest?

since i mostly do 1cd-rips with mp3 and 2cd-rips with ac3 i am looking for a reasonable size/quality setting with a little more weight on quality.

thanx and regards again
/jc

wasting lots of space when encoding a movie?!

Reply #3
this is my first post here and what i say isnt gospel but i thought it would be time to contribute

mp3 isnt really suited for your one cd rips as its VBR functions are currently not great...a better solution would be ogg vorbis audio which is completely vbr, as far as i know anyway

wasting lots of space when encoding a movie?!

Reply #4
yes, it might even be better. the even is the problem. i never find time to get into it, to bad.. i know i sholud, but for now i´ll stick with mp3.

i guess the next cedec i´ll really have to find time for will be aac anyway..
/jc

wasting lots of space when encoding a movie?!

Reply #5
im not sure if my pimping will be frowned upon but over at doom9.org there are some excellent guides for encoding your ac3 file into an ogg vorbis file and then muxing it with the video

wasting lots of space when encoding a movie?!

Reply #6
sure, i know. but as i said, i have to find the time. a completely new format is a demanding thing. but thanks for caring.
/jc

wasting lots of space when encoding a movie?!

Reply #7
I realy wouldn't recommend you to use mp3 for a DivX rip. Ogg Vorbis is by far the best choice, not only quality-wise but the Ogg container format is also superior to avi, it allows easily multiple audio-streams, wastes less space on muxing overhead (a vbr-mp3 stream muxed inside an avi produces an huge overhead), seeking works better, etc. Since I started to use Ogg for my DivX rips I'd never ever go back to avi/mp3!

wasting lots of space when encoding a movie?!

Reply #8
as i said: i should surely give it a look, just dunno when.
/jc

wasting lots of space when encoding a movie?!

Reply #9
There realy no big obstacles in using Ogg Vorbis. If you are using Guardian Knot, it takes you perhaps ten or twenty minutes to figure out how to do it, after that you can do your rips just as easy as before. You only need two little utilities: HeadAC3he and OggMux, the former you need to transcode from wav to Ogg Vorbis. You have to do that before you encode the movie in Guardian Knot. Then you simply enter the filesize in Guardian Knot and de-check the "Calculate Frame-Overhead" box. You have to consider the overhead manually - it's about 2MB for a 1CD-rip. Now you encode the movie as usually, and finaly you take OggMux to mux movie and audio together (it's a very plain tool - no need to set any parameters or something, simply select the files you want to mux and hit the button). That's it!

wasting lots of space when encoding a movie?!

Reply #10
personally i would recommend Ogg Machine for the audio encoding

wasting lots of space when encoding a movie?!

Reply #11
@UHT: What's the advantage of using OggMachine over HeadAC3he? Both do exactly the same job, or am I wrong?

wasting lots of space when encoding a movie?!

Reply #12
There *are* disadvantages to using Ogg as the movie container format - support on non-Windows OSes.

You'd imagine that the Linux software crowd would be very quick on the uptake with a completely open container format / audio format / etc., but the Windows coders have them beat. I've not yet found a way to playback Ogg movies in Linux. Until a way exists, I'm sticking to AVI with MP3 audio (although I've moved to XviD for video - this is fine as standard DIVX players can understand XviD, being as it's all MPEG-4).

I just use the LAME --alt-presets, with no other switches - --alt-preset 160 for a 90 minute movie is generally fine.

As to the original question (about silence) - I don't have an answer for you. In general, what you see as 'silence' in a movie *isn't* real digital silence - you have lots of background noise. You can filter the audio to remove this background noise, but unless you do it well, you'll end up creating artifacts. Ogg wouldn't be a panacea here - it tends to use quite high bitrates for background noise (often higher bitrates than for the actual music/speech).

wasting lots of space when encoding a movie?!

Reply #13
I've been happily doing all my encodes in Ogg/XviD/Vorbis and never looked back since I made the switch. I mostly follow the guide at http://www.everwicked.com

I prefer Headac3e over Ogg Machine. They are pretty much similar, but normalizing is a faster using Headac3e through an intermediary file as you don't need an extra pass (needs some spare HD space though, but that shouldn't be a problem)