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Old 2004-10-15, 13:42   Link #1
GarBhaD
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Join Date: Nov 2003
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why re-encoding audio?

I noticed that most fansub groups re-encode video and audio from the raws which generates quality loss. The video encoding is unavoidable because of hardsubs nature (if softsubs are better or not it's not the topic here).
What I don't understand is why do you re-encode audio too. If you have watched (and heard) a raw before, the lost quality is very noticiable even without headphones, and I don't have an exigent hearing, believe me.
A very clear example would be the old episodes of ANBU-AonE's Naruto, where the opening theme made my ears bleed everytime I heard it. Specifically the 3rd and 4th op.
Well, maybe I'm exaggerating but it's pretty annoying when you know that you could avoid it easily.
So please, could at least tell me why do you do it?
The only reason I thought off is to shrink the filesize, but the difference would be ridiculous, if you compare it with the quality you lost.
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Old 2004-10-15, 14:00   Link #2
_yeah
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Many raws contain VBR audio.

VirtualDub does not handle VBR audio properly, and since we all use VirtualDub to encode our episodes, most encoders re-encode the audio to 128kbps MP3 CBR.

Otherwise, it becomes a desynced mess.
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Old 2004-10-15, 14:07   Link #3
babbito2k
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The music of a show might not sound as good when the sound is re-encoded but most of the audio for a show consists of voice and sound effects, which don't need a lot of headroom to sound good. I can live with the tradeoff. There are other considerations as well.

One thing I am a bit stumped by is that there are older shows with a monaural soundtrack which get encoded in stereo. A mono encoding of the sound would either be half as large for the same quality or be twice as good for the same size audio track.
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Old 2004-10-15, 14:30   Link #4
GarBhaD
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Quote:
Originally Posted by _yeah
Many raws contain VBR audio.

VirtualDub does not handle VBR audio properly, and since we all use VirtualDub to encode our episodes, most encoders re-encode the audio to 128kbps MP3 CBR.

Otherwise, it becomes a desynced mess.
I didn't think about that. That's indeed a problem.
A solution would be finding a raw that has CBR audio (there are), but I understand that it can be a pain in the ass.
I downloaded recently Naruto 104 raw to watch the new op-ed in all it's "glory" and the quality is incredible. Both audio and video are crystal-clear quality. By the way, the audio was 160kbps CBR. If fansubs could always be like that...
(Sorry if I'm only using Naruto as an example but it's been the last one I dl'ed).
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Old 2004-10-15, 14:49   Link #5
teh_suck
AKA Torgen from We Suck
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I make a point of always using a raw for Survive which has CBR audio, so we don't have to re-encode it. This tends to work out, since when I get home from work Thursday nights, Winny has usually downloaded about 3 raws for the most recent episode, and there's always at least one with CBR.
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Old 2004-10-15, 15:00   Link #6
Akirasuto.
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Sometimes you also have re-encode the audio if you add extra sections such as notes.
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Old 2004-10-15, 15:47   Link #7
cagz
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Join Date: Aug 2004
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There is also the problem of raws may have good audio, but they will have shit video quality. Sometimes you have to choose and honestly it's 500x quicker to recode audio; then use heavy video filters. There's also the fact of personal preference, I'd rather my video to look high quality.

Edit: However if you can get away with both, hell yer!
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Old 2004-10-15, 15:50   Link #8
boneyjellyfish
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Quote:
Originally Posted by _yeah
Many raws contain VBR audio.

VirtualDub does not handle VBR audio properly, and since we all use VirtualDub to encode our episodes, most encoders re-encode the audio to 128kbps MP3 CBR.

Otherwise, it becomes a desynced mess.
Here's how I fix that: Run file through VirtualDubMod; Demux the mp3 stream; disable the audio and encode normally; then mux the mp3 stream back in with Nandub. No audio re-encoding necessary, and there's less encoding time overall.
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Old 2004-10-15, 17:03   Link #9
crumja
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Often, the audio file size will be too big. Many raws nowadays are ~ 192 kbps, mostly ABR.

Therefore, it is necessary to reduce the audio size to ~ 22 MB in order to retain video quality.
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Old 2004-10-15, 21:05   Link #10
JediNight
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Good tip boneyjellyfish, I didn't think of trying Nandub. I normally use 1.5.10.1, but Koroshiya told me to try 1.5.1.1 bc it supposedly didn't have the audio problems. Apparently for him (using Win2K3) he is able to just Demux the MP3 and Remux it in after the Video is done encoding. That does not work for me however. So I just pull the audio into Cooledit Pro and convert to 160kbit CBR which still sounds nice. It also allows me to filter out click/hiss in the audio if there is some.
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Old 2004-10-15, 23:07   Link #11
NinjaServ
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unless you get the raw from the same person the audio can vary in size, most encoders like to stay "consistant" and keep it at a smaller rate and put more towards the video (where it is REALLY needed). Only other excuse i've seen was Lunar Anime with the Title screens, you have to re-encode to audio to do that.
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Old 2004-10-15, 23:42   Link #12
Sylf
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I always keep the original audio - to me, sound quality means a lot. mp3 is a lossy format to start with, reencoding is just a killer.
Just like the previous posts, Nandub works good to mux VBR audio, as well as AVIMux_GUI.
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Old 2004-10-16, 00:02   Link #13
NinjaServ
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This baffles me...ppl BITCH about videos being TOO large then they are like "BUT KEEP THE ORIGINAL AUDIDO!!!", so ppl want CLEAR as hell audio and EXTREMELY fucked up picture quality???
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Old 2004-10-16, 07:49   Link #14
SirCanealot
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Yes, I HATE groups re-encoding the audio too, which is why I NEVER do it.

Look, try VirtualDubMod:
http://www.williams1.homechoice.co.uk/VBRVDMod.jpg
It's not even funny, I've pressed that button every time, and not only have I never had any problems, but I've never heard of any problems.
This process 100% conforms to my basic use of computers: if it asks you for something, mash "yes", if it asks you if you want it to do something, mash "no".

Even if VirtualDubMod DID have problems with VBR audio, then use another muxer! How old is .avi? There's probably 1000s (that isn't even sarcasm - there probably IS) of programs that can be used to Mux a .avi file together.
The only time I'd EVER re-encode the audio, is if I have high-bitrate CBR audio - like 196, which IS a waste - since I can take it down to around 140kbs VBR with Winlame or another simple recompression program with little quality loss.

And HOW do you even need that much space? We're talking about about 31 megs for PRESTINE audio. Are you telling me you can't spare 25 or 50kbs from the video? We're encoding at around 900kbs for a 175 meg show: 50kbs is not going to mean the death of your video, provided you've got half a brain for packing episodes down in the first place.
And even if you DID need the space for the video THAT badly, why 128CBR? Why not 128ABR? Same filesize, increased quality.
I have to admit, I do miss that extra bitrate, but if it means the end product has PRESTINE audio, then what am I to care? Even if it DID turn the episode into a blocky mess (which it won't), people can use Post-Processing to fix that up (a little). There's no such Post-Processing for 128CBR audio!
The only time I've ever felt the NEED to reduce audio filesize, if when I had a high-motion episode of Naruto: I took it down from 31 megs to around 24 megs or so - still VBR.

It's a complete MYTH that there are problems with correctly muxed VBR audio in .avi on PLAYBACK. And even if 1 in 1000 people did have a problem, it's hardly any effort for them to re-encode to 320kbs CBR temporarily (to lose little quality).

This issue is one that REALLY annoys me, as in my opinion is shows ignorance and unskill in encoders, and this forum post is likely to change NOTHING.

Actually, it's not like it's the DEATH of me when watching a fansub. Although, it does mean some ops sound like TRASH. But it's just the princible of the thing, damnit.

Although, my method of Post-Processing (http://www.williams1.homechoice.co.u...sing-small.jpg) does nothing for bad audio
Heh, and for anyone thinking they can slack of in editing, but include the original VBR audio, and think they can still curry favour from me, I've got 50lbls of Nuclear waiting just for you!!
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Old 2004-10-16, 08:16   Link #15
GarBhaD
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Very well said, man Audio quality is more important than most encoders think.

TV is sure the best post-processing method: even the blockiest videos look perfect. Isn't it because of the poor definition of tv screens vs monitors and their high contrast?

And I don't think fansubbers should care that much about the filesize. Why not having both good video and audio? After all, there are episodes with more that 200MB and people still download'em. And the number of people with broadband (256kbps and more) grows everyday. I haven't seen anyone bitching about filesize before. Well, I don't dwell on fansubbers' channels or forums too much but even if some ppl complain about it, I doubt it would affect the number of downloads.
The only problem would be the CD storage, but nowadays DVD burners are ridiculously cheap. The same goes for DVD media. And if you buy anime DVD's, having a DVD burner is essential to make backups of your original discs

Times change. And maybe encoders should start to reconsider their methods and aim to a bigger filesize. But that discussion deserves its own thread...
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Old 2004-10-16, 08:22   Link #16
SirCanealot
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Quote:
Originally Posted by GarBhaD
TV is sure the best post-processing method: even the blockiest videos look perfect. Isn't it because of the poor definition of tv screens vs monitors and their high contrast?
SDTVs are just blury, and yes the contrast is never as good. Also, you normally sit MUCH futher back from a TV than from a monitor (my eyes are pretty bad at that distance, so even with glasses on, I'm pretty bad at spoting fine blocking which I'd see on the TV at 12 inchs, heh). I'm usually around 8-12"s from my monitor, but a good 10-12 foot from my TV. Nicely, my SD TV is still fairly sharp, so I wouldn't even say it blurs out much fine detail: maybe as much FFDShow's postprocessing with far improved noise reduction :P
Also, I can run a LancZos up to 720x540 with the Sharpen filters on a little, which doesn't really increase artifacts (since the TV is bluring them all out), and gives me a nice boost in sharpness.
This is one of the reasons I have NO interest in a HDTV - shitty quality fansubs just look too good on my old-ass SDTV :P

For everyone's information, an SDTV is:
Anti Blocking
Anti Pastelling
Can make the worse of encoding look almost like prestine DVD (well, sort of).
I've been shocked at times when switching over to the ol' monitor and looking at the crap I've been watching on my TV, that I thought looked very l33t.
Heh, that's why I DO get pissed off when I see blocking or pastelling on my TV - the TV compensates for it so much, it has to be VERY bad for me to be able to see it :P

Quote:
And I don't think fansubbers should care that much about the filesize.
Heh, there IS a topic on this - look for the closed topic, haha.

And my argument is merly: it's 10 megs! Yes, that's a decent bit of video bitrate, but far from the end of the world. It's 10 megs for gold insted of bronze!
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Old 2004-10-16, 10:16   Link #17
StarCreator
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I can't condone VBR audio within AVI. At all. It's a hack that shouldn't be allowed to exist.

The AVI container was simply not designed for VBR audio. Why do you think kosher Vdub has no support for it? It breaks any standards AVI still has left and makes a file that is only remotely playable correctly in a DirectShow app - despite the complete mangling it does to the format.

I'm surprised that no one in this thread seemed to know this.
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Old 2004-10-16, 10:36   Link #18
SirCanealot
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B-Frames = "hack"
Mpeg4 = "hack"
Mp3 (CBR) = "hack"

Why not just "hack" some more?
Hell, even mpeg4 in .mkv is still a "hack" as far as I remember reading from what the development team was saying, haha.
What WAS the .avi container originally designed for, then? XVid and mp3? Yeah right.
I have to quote this again: http://www-user.tu-chemnitz.de/~noe/...containers.pdf
Although, it does make the point about DirectShow.
Out of curiosity, what wouldn't be considered "DirectShow" or, able to simulate DirectShow's behaviour?
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Old 2004-10-16, 10:58   Link #19
Cruzz
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I'm somewhat surprised that most people haven't started using AVI-Mux GUI for the muxing process. Do people really like Virtualdub's audio-handling that much?

Quote:
Originally Posted by SirCanealot
Out of curiosity, what wouldn't be considered "DirectShow" or, able to simulate DirectShow's behaviour?
The document is obviously referring to any program that uses ACM instead of Directshow for audio handling.
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Old 2004-10-16, 16:35   Link #20
cagz
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Join Date: Aug 2004
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I was going to refrain from commenting about vbr and cbr audio.. but since someone brought it up i'm going to add my 2c.
Now I'm not going to go into the technical detail about why vbr should not be used, i'm going to tell you to read the Virtualdubmod FAQ, once you've done that come back and read the last few sentences of this post.

VBR mp3 in avi; is a hack pure and simple, a very bad one at that. It should never ever be used again in a legacy avi container for the reasons given in the faq. CBR is the correct way to go and to be honest there is not alot of difference if it's reencoded correctly.

So now your going to tell me, but vbr is better blah blah. Well yes this may be the case (personally i can hardly tell the difference), anyhow... this is inpart why the matroska and ogm containers are so much better. They actually fully support vbr in either mp3 or ogg, they are capable of softsubs and matroska supports vfr (variable frame rate).

Ok.. so why arn't fansub groups using matroska. The primary reason being it's not compatabile with the current home mpeg4 players (excluding xbox), people don't know what it is and also using a softsub .ssa i'm told requires a fair amount of cpu power.

The last thing I have to say is that groups may change formats in the new year... who knows i hope they do, anyway i just want to make it clear i don't hate vbr audio, i just hate it being used in a container that was never designed for it.

Last edited by cagz; 2004-10-16 at 16:52.
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