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An idea of audio encode algorithm, based on maximum allowed volume of , WavPack hybrid mode test included
softrunner
post Mar 6 2013, 00:11
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Full topic title: "An idea of audio encode algorithm, based on maximum allowed volume of signals difference"

Recently I have discovered for myself, that the difference of the source and encoded audio can be easily obtained by inverting source audio and mixing it with the encoded one. Then the idea of encode algorithm came into my head: just try to keep the signals difference at the same level (or less), defined by user. Thus, the audio quality is simply measured by volume of the difference of the signals, and this difference is nothing but distortions, produced by encoder.
The whole algorithm looks like this:
1. Take maximum allowed volume of signals difference from user.
1. Make a copy of source audio and invert it.
2. Split both source and inverted audio on frames of the same size.
3. Encode first frame of source audio, mix the result with first frame of inverted audio and calculate the volume of obtained difference.
4. If the volume of the difference is higher, than allowed by user, add some bitrate and repeat from item no. 3.
5. If the volume of the difference is not higher, than allowed by user, add first encoded frame to the final output.
6. Repeat items 3-5 with second, third, etc... frames, until the end of the source file.

Of cause, this algorithm is much slower then just direct encode, but definately if should not be slower, than video encoding (and people are ready to wait for many hours while their videos are being encoded).

I tried to reproduce this algorithm manually by test using WavPack hybrid mode as an encoder (source audio sample was splitted on 11 parts of 1 second), and it showed, that 23.4 % of space/bitrate could be saved. Another important thing is that the user is guaranteed, that he will not get distortions with volume level, higher then he expects, so he can safely encode many files simultaneously without looking at the content. User gets freed both from unnecessary waste of bitrate and uncontrolled distortions.

The only thing is needed is that some audio developers get interested in this idea and implement it as a computer program.

The whole set of files of the WavPack test I've made is here.

This post has been edited by softrunner: Mar 6 2013, 00:20
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softrunner
post Mar 25 2013, 03:10
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QUOTE (saratoga @ Mar 22 2013, 06:24) *
QUOTE (softrunner @ Mar 21 2013, 21:16) *
QUOTE (C.R.Helmrich @ Mar 13 2013, 00:46) *
Convert some CD audio to 8 bit/sample, that gives you the ~45 dB difference level you want. You'll find it's not enough for many music files, especially ones with long fade-outs.

If do it without dithering, the noise will be about -1.4 dB, and if use dithering, yes, it will be about -45 dB, but it all will be in high frequencies, so using equalizer will make it easily audible.

The audio quality of this approach will already be poor. If you're also going to use EQ, you should absolutely apply it BEFORE you encode. Otherwise you will need to tolerate much lower quality or else even higher bitrates.

Yes, but, I did not say, that -45 dB, given by this approach, and -45 dB, given by WavPack hybrid, are of the same quality. Definately they are not. I wrote only about WavPack, which I had tested.

QUOTE (Gecko @ Mar 22 2013, 11:48) *
You seem to be looking for some form of holy grail of lossy audio encoding: great compression, zero artifacts, super simple algorithm. Many smart people have spent a lot of time and effort to give us good compression and few artifacts. But the algorithms involved usually aren't very simple.

No, the idea is in running already existing encoders many times (increasing bitrate) until they give proper result. And the decision of how proper the result is, should be made by computer program at runtime. Of course, every encoder has its own properties, so the way of the evaluation of the result should consider this properties.

QUOTE (db1989 @ Mar 22 2013, 14:51) *
QUOTE
It depends on what to call "transparent".
The irony is strong with this one. How do you define “transparent”, then? To me, it seems as though your ideal definition is transparency for everyone all the time. Setting aside how patently absurd that idea is since transparency specifically refers to specific combinations of listener and material, your pointing out how a codec that is usually transparent at much more sensible bitrates fails to be transparent at a very high bitrate with one particular sample does not support your argument: it’s actually undercutting it. There will always be exceptions to transparency, at least for certain people and certain signals, and none of your nice-sounding-in-novice-theory-but-baseless-in-practice ideas are likely to change that. At least develop a consistent narrative before you try to make everyone implement it at your behest.

I do not use the word "transparent" at all. I prefer audible/inaudible instead. Yes, my approach is that the difference should be inaudible for all humans (not dogs, cats, snakes etc.). We are humans, so there are restrictions of our perceptibility. If you do not hear the difference, it does not mean, that it is not there, and if the difference is there, it does not mean, that you (any human) can hear it. Audio listening is an objective thing. Usually people do not hear the difference because they are not attentive, patent etc. enough. They actually can do it, but silent mind is needed first.
In my opinion, for encoder there should not be any exceptions of input audio (when you try to substitute lossless). Otherwise, use Opus 208 kbps and be happy. It gives high quality for all types of music.

QUOTE (2Bdecided @ Mar 22 2013, 17:43) *
Are you saying that lossyWAV standard without noise shaping is transparent?

I can not say for sure. At 32 kHz sample it is audible, for 44 kHz and higher it is probably not, but deeper tests are needed. (with adaptive noise shaping 44 kHz is audible)
QUOTE
If I've understood you correctly, I think it's the closest thing you're going to get to your goal.

Yes, as far, as I tested it, it can be safely used instead of lossless.
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probedb
post Mar 25 2013, 16:44
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QUOTE (softrunner @ Mar 25 2013, 02:10) *
No, the idea is in running already existing encoders many times (increasing bitrate) until they give proper result. And the decision of how proper the result is, should be made by computer program at runtime. Of course, every encoder has its own properties, so the way of the evaluation of the result should consider this properties.

Surely this could leave said program running indefinitely due to never matching the criteria? How do you define 'proper' for every possible type of audio?

QUOTE (softrunner @ Mar 25 2013, 02:10) *
I do not use the word "transparent" at all. I prefer audible/inaudible instead. Yes, my approach is that the difference should be inaudible for all humans (not dogs, cats, snakes etc.).

So you don't think that when someone says something is 'transparent' to them that they don't mean that all artifacts are 'inaudible' to them? I don't think you understand what transparency is.

This post has been edited by probedb: Mar 25 2013, 16:45
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Posts in this topic
- softrunner   An idea of audio encode algorithm, based on maximum allowed volume of   Mar 6 2013, 00:11
- - saratoga   QUOTE Then the idea of encode algorithm came into ...   Mar 6 2013, 00:21
|- - softrunner   QUOTE (saratoga @ Mar 6 2013, 03:21) The ...   Mar 6 2013, 00:36
|- - saratoga   QUOTE (softrunner @ Mar 5 2013, 18:36) I...   Mar 6 2013, 00:58
- - greynol   None of the lossy codecs commonly discussed on thi...   Mar 6 2013, 02:22
- - DVDdoug   softrunner, If you want to demonstrate to yoursel...   Mar 6 2013, 21:01
- - C.R.Helmrich   QUOTE (softrunner @ Mar 6 2013, 00:11) ju...   Mar 6 2013, 21:21
|- - softrunner   QUOTE (saratoga @ Mar 6 2013, 03:21) The ...   Mar 7 2013, 16:59
|- - 2Bdecided   QUOTE (softrunner @ Mar 7 2013, 15:59) We...   Mar 7 2013, 17:14
|- - greynol   LossyWAV is commonly discussed here and I lamented...   Mar 7 2013, 18:05
||- - saratoga   QUOTE (greynol @ Mar 7 2013, 12:05) Lossy...   Mar 7 2013, 20:25
|- - db1989   QUOTE (softrunner @ Mar 7 2013, 15:59) We...   Mar 7 2013, 18:51
||- - Canar   QUOTE (softrunner @ Mar 7 2013, 15:59) We...   Mar 7 2013, 20:20
|- - Nessuno   QUOTE (softrunner @ Mar 7 2013, 16:59) Bu...   Mar 7 2013, 20:54
|- - C.R.Helmrich   Indeed. Softrunner, if you want mathematical close...   Mar 7 2013, 22:51
- - greynol   @Canar: Please show me a lossy algorithm with no ...   Mar 7 2013, 20:29
|- - Canar   QUOTE (greynol @ Mar 7 2013, 11:29) Pleas...   Mar 7 2013, 20:32
- - softrunner   QUOTE (2Bdecided @ Mar 7 2013, 20:14) You...   Mar 9 2013, 03:09
|- - saratoga   QUOTE (softrunner @ Mar 8 2013, 21:09) QU...   Mar 9 2013, 04:00
|- - greynol   QUOTE (softrunner @ Mar 8 2013, 18:09) Th...   Mar 9 2013, 08:31
|- - Nessuno   softrunner, you evidently lack the theorical bases...   Mar 9 2013, 10:15
|- - db1989   In support of Nessuno’s conclusions, as well as th...   Mar 9 2013, 11:53
||- - greynol   QUOTE (db1989 @ Mar 9 2013, 02:53) * And ...   Mar 9 2013, 17:55
|- - 2Bdecided   QUOTE (softrunner @ Mar 9 2013, 02:09) Th...   Mar 12 2013, 10:47
||- - Dynamic   Lossless is the only true guarantee. LossyWAV...   Mar 12 2013, 12:42
|- - C.R.Helmrich   QUOTE (softrunner @ Mar 9 2013, 03:09) QU...   Mar 12 2013, 21:46
- - Gecko   On a very basic level, lossy encoders have a mecha...   Mar 9 2013, 12:06
- - greynol   So WavPack does have a psychoacoustic model?   Mar 9 2013, 17:46
|- - Gecko   QUOTE (greynol @ Mar 9 2013, 17:46) So Wa...   Mar 10 2013, 17:10
- - greynol   If you know then say.   Mar 10 2013, 17:50
- - Gecko   Well, since Wavpack lossy doesn't just discard...   Mar 10 2013, 19:16
- - greynol   Sorry, but that really doesn't cut it. Could ...   Mar 10 2013, 19:31
- - Gecko   In that case, maybe I need to revise my definition...   Mar 11 2013, 18:49
- - pdq   Can you play the correction file to a Wavpack loss...   Mar 11 2013, 19:25
- - Gecko   I tried the old inversion trick on a drum & ba...   Mar 11 2013, 20:02
|- - bryant   QUOTE (Gecko @ Mar 11 2013, 11:02) I trie...   Mar 28 2013, 04:59
- - db1989   Premises: (1) If a residual signal created by mixi...   Mar 11 2013, 20:21
- - greynol   For the record, I'm not in any position to def...   Mar 11 2013, 20:56
|- - Nessuno   QUOTE (greynol @ Mar 11 2013, 20:56) At a...   Mar 11 2013, 21:57
- - softrunner   QUOTE (2Bdecided @ Mar 12 2013, 13:47) QU...   Mar 22 2013, 03:16
|- - saratoga   QUOTE (softrunner @ Mar 21 2013, 21:16) Q...   Mar 22 2013, 03:24
|- - Gecko   QUOTE (softrunner @ Mar 22 2013, 03:16) B...   Mar 22 2013, 08:48
|- - db1989   QUOTE (softrunner @ Mar 22 2013, 02:16) Q...   Mar 22 2013, 11:51
||- - 2Bdecided   QUOTE (db1989 @ Mar 22 2013, 10:51) QUOTE...   Mar 22 2013, 14:57
||- - db1989   QUOTE (2Bdecided @ Mar 22 2013, 13:57) QU...   Mar 22 2013, 15:20
|- - 2Bdecided   QUOTE (softrunner @ Mar 22 2013, 02:16) I...   Mar 22 2013, 14:43
- - jmvalin   Hey everyone, I just had this great idea that shou...   Mar 22 2013, 07:41
- - 2Bdecided   Sorry db1989, I'm not trying to personally att...   Mar 22 2013, 16:37
|- - db1989   QUOTE (2Bdecided @ Mar 22 2013, 15:37) So...   Mar 22 2013, 18:24
|- - Nessuno   QUOTE (2Bdecided @ Mar 22 2013, 16:37) Le...   Mar 23 2013, 11:00
|- - 2Bdecided   QUOTE (Nessuno @ Mar 23 2013, 10:00) QUOT...   Mar 28 2013, 10:34
|- - db1989   QUOTE (2Bdecided @ Mar 28 2013, 09:34) If...   Mar 28 2013, 13:41
||- - 2Bdecided   QUOTE (db1989 @ Mar 28 2013, 12:41) QUOTE...   Mar 28 2013, 17:30
|||- - db1989   QUOTE (2Bdecided @ Mar 28 2013, 16:30) Ah...   Mar 28 2013, 17:38
||- - DonP   QUOTE (db1989 @ Mar 28 2013, 07:41) QUOTE...   Mar 28 2013, 17:45
||- - db1989   QUOTE (DonP @ Mar 28 2013, 16:45) First, ...   Mar 28 2013, 17:50
||- - Nessuno   QUOTE (db1989 @ Mar 28 2013, 17:50) QUOTE...   Mar 28 2013, 22:29
|- - jmvalin   QUOTE (2Bdecided @ Mar 28 2013, 05:34) It...   Mar 28 2013, 19:42
- - 2Bdecided   RE: An idea of audio encode algorithm, based on maximum allowed volume of   Mar 22 2013, 18:49
- - softrunner   QUOTE (saratoga @ Mar 22 2013, 06:24) QUO...   Mar 25 2013, 03:10
|- - lvqcl   QUOTE (softrunner @ Mar 25 2013, 06:10) A...   Mar 25 2013, 16:12
|- - probedb   QUOTE (softrunner @ Mar 25 2013, 02:10) N...   Mar 25 2013, 16:44
|- - Gecko   QUOTE (softrunner @ Mar 25 2013, 03:10) N...   Mar 25 2013, 18:22
- - greynol   Thanks for chiming-in, David!   Mar 28 2013, 07:20
- - 2Bdecided   I think he implied a noise floor relative to peak ...   Mar 28 2013, 21:19
- - jmvalin   QUOTE (2Bdecided @ Mar 28 2013, 16:19) I ...   Mar 28 2013, 21:49
- - 2Bdecided   QUOTE (jmvalin @ Mar 28 2013, 20:49) I...   Mar 29 2013, 12:16


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