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Topic: Ogg-mp4 Audio-Video New Quality Settings Proposal (Read 3512 times) previous topic - next topic
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Ogg-mp4 Audio-Video New Quality Settings Proposal

Hi all, several months ago I posted some weird topics here about alternative Vorbis Quality Settings but (despite being convinced Vorbis's Quality Settings were not as they should have been) I was still un-satisfayed (& obviously HA users too  of my alternative result ... but with Theora beta1 being out soon I asked myself what will be Theora Quality Settings, so I thought about how I would like them to be before it gets too late to change them (as my previous posts shown me that the idea of changing Vorbis Quality Setting was not well accepted at all) so I re-started building an harmonized Vorbis Vs. Theora Bitrates grid & this time I was so satisfayed of the result that I thought I had to share it before Theora Beta1 gets out ...  so here it is

NB: What follows has nothing to do with listening-visual tests & is in no way a try to teach you what bitrate is the "best" in practice ...  but I hope it will helps you understand how bitrate increases & what is "theorically" an optimized bitrate

Audio Bitrates:
Range 1 - 0040-0048-0056-0064Kbps (+008Kbps Step)
Range 2 - 0080-0096-0112-0128Kbps (+016Kbps Step)
Range 3 - 0160-0192-0224-0256Kbps (+032Kbps Step)
Video Bitrates:
Range 1 - 0320-0384-0448-0512Kbps (+064Kbps Step)
Range 2 - 0640-0768-0896-1024Kbps (+128Kbps Step)
Range 3 - 1280-1536-1792-2048Kbps (+256Kbps Step)

Range 1 -  - -- Low Quality Bitrate Range (for Streaming)
Range 2 - Medium Quality Bitrate Range (for Portable)
Range 3 - - High Quality Bitrate Range (for Backup)

or

---- - --Audio-- - --1H30- - --Video-- - --1H30- - --A+V--- - --1H30-
Range 1:                                                           
Q01 - 040Kbps - 026MO - 0320Kbps - 0210MO - 0360Kbps - 0237MO
Q02 - 048Kbps - 031MO - 0384Kbps - 0253MO - 0432Kbps - 0284MO
Q03 - 056Kbps - 036MO - 0448Kbps - 0295MO - 0504Kbps - 0332MO
Q04 - 064Kbps - 042MO - 0512Kbps - 0337MO - 0576Kbps - 0379MO
Range 2:
Q05 - 080Kbps - 052MO - 0640Kbps - 0421MO - 0720Kbps - 0474MO
Q06 - 096Kbps - 063MO - 0768Kbps - 0506MO - 0864Kbps - 0569MO
Q07 - 112Kbps - 073MO - 0896Kbps - 0590MO - 1008Kbps - 0664MO
Q08 - 128Kbps - 084MO - 1024Kbps - 0675MO - 1152Kbps - 0759MO
Range 3:
Q09 - 160Kbps - 105MO - 1280Kbps - 0843MO - 1440Kbps - 0949MO
Q10 - 192Kbps - 126MO - 1536Kbps - 1012MO - 1728Kbps - 1139MO
Q11 - 224Kbps - 147MO - 1792Kbps - 1181MO - 2016Kbps - 1328MO
Q12 - 256Kbps - 168MO - 2048Kbps - 1350MO - 2304Kbps - 1518MO

(Size Calculation:
1024XBitrate/1024/1024XSec/8= Bitrate/1024X5400/8)

Range 1 -  - -- Low Quality Bitrate Range (for Streaming)
Range 2 - Medium Quality Bitrate Range (for Portable)
Range 3 - - High Quality Bitrate Range (for Backup)

Slider Preview
Audio :
Q1--Q2--Q3--Q4--Q5--Q6--Q7--Q8--Q9--Q10--Q11--Q12
Video :
Q1--Q2--Q3--Q4--Q5--Q6--Q7--Q8--Q9--Q10--Q11--Q12
Easy, isn't it ?

8KbpsX(Multiple of 5)= Size Vs. Quality Optimized Bitrates
0040-0080-0160 are halved+1 (X05, X10, X020) multiple of 8Kbps & so are 3 audio ripping golden numbers (LQ-MQ-HQ).
0320-0640-1280 are halved+1 (X40, X80, X160) multiple of 8Kbps & so are 3 video ripping golden numbers (LQ-MQ-HQ).
Each of these birates are Quality Vs. Size optimized for the targeted use.

8KkpsX(Multiple of 8)= Quality Only Optimized Bitrates
0064-0128-0256 are full (X08, X016, X032) multiple of 8Kbps & so are 3 audio ripping golden numbers (LQ-MQ-HQ).
0512-1024-2048 are full (X64, X128, X256) multiple of 8Kbps & so are 3 audio ripping golden numbers (LQ-MQ-HQ).
Each of these birates are Quality Only (not Size) optimized for the targeted use.

Default Setting:
Q8 for DVD Theora+Vorbis 1024Kbps+128Kbps
Q9 for CD Vorbis 160Kbps

Why Q8 for DVD while Q9 for CD ?:
Because the audio source of DVD (AC3) is already 192Kbps (2.0) or 192KbpsX2=384Kbps (5.1) so transparency here is a myth, it don't worth it transcoding in the same range, & as 192Kbps is in the +32Kbps by Step Range (160 to 256Kbps) ... you have to rip the audio in the range below, the +16Kbps by Step Range (80 to 128Kbps) & as 128Kbps is the best setting in that range, it is the best setting for AC3 transcoding.

Why 1024Kbps ?
1024Kbps is the video bitrate equivalent to an audio bitrate of 128Kbps in the grid.

If DVD(Mpeg2+AC3) were lossless as CD then 1280Kbps+160Kbps would be the theoric optimal points, as it is with CD, but as DVD is lossy it's 1024Kbps+128Kbps.

Edit: I may use 1280+160Kbps with HD-DVD depending on source quality, but I use 1024+128kbps for DVD.

My Q8 is specially good for video backup on DVD as ripping with a target size 700mo(1CD) 1400mo(2CD) will soon become obsolete & people will start using target bitrate instead of target size like in the audio ripping world ... so ending with a Q8 rip around 1go (Video+1AudioStream=779MO for 2.0, 843MO for 5.1) rip will be perfect for DVD backup ...

After understanding all this, it gets suddenly all clear in my mind that I was a
160Kbps to 256Kbps for Audio User &
640+80Kbps to 1024+128Kbps for Video User (for basic DVD at last) &
that there were no "perfect bitrate" ... but only 3 good ranges for 3 specific uses & that it doesn't matter what bitrate you use as long as you know what you are doing & are targetting the good range for your specific use.

I wish Ogg Vorbis-Theora (& Mpeg4 AAC-AVC) dev (& users) could read this, & tell me if they like the result & if not ... why? (I specially wrote the topic to point Theora dev on IRC to it, & maybe Xiphmont next time I see him ...)

Anyway my previous experience about trying to get better quality settings teached me that this kind of consideration is generally badly welcomed so I have no illusion at all that other people would like (or at last understand ...) what I have in mind ... in the end only the dev choses ... so who care about my opinion ...

At last I hope that the grid helped you understand that 128Kbps is not a WAV coding bitrate but a AC3 transcoding bitrate ... & why 192Kbps despite being the accepted MP3 point of transparency is not "theorically" the most optimized Size Vs. Quality ratio for Vorbis/AAC backup ... it's 160Kbps (but 192Kbps is in the good range for the backup use so in the end it doesn't matter ... both are good for this use)

Special Note To Nero AAC devs: I hope the grid also helped you understand that Nero HE should ends at 79.99Kbps & not a 80Kbps as it is the case now ... 80Kbps is IMHO "theorically" starting point for AAC LC ...
Edit: Just tested Ateme AVC & get the surprise that HE goes up to 128kbps now ... so nevermind about what I was saying ...  I disagree but that's just me ...

Hoping I don't get hundred of flaming posts telling me how this grid is stupid  ... HR