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Lossless Extensions for Opus (Backwards Compatible), How to embed lossless deltas inside an Opus stream
wswartzendruber
post Feb 24 2013, 19:58
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After reading a good chunk of the Opus RFC, I believe it may be possible to use Opus padding to embed lossless deltas for each packet. It states that this padding may be of any size, and that while an Opus encoder itself must set any padding to zero, the decoder must accept any value. It also states that when the decoder has finished reading bytes from a frame for decoding, it may not spill over into the padding for further input. Hrm... Sounds like an arbitrary extension field to me.

My only concern is about just how much padding decoders would be willing to accept before deciding that the packet is a DOS attack.
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wswartzendruber
post Feb 25 2013, 05:18
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I also missed the part above where this proposition will mess up seeking. I'm hoping someone can explain why. That seems more like a container issue to me.
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jmvalin
post Feb 25 2013, 05:43
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QUOTE (wswartzendruber @ Feb 24 2013, 23:18) *
I also missed the part above where this proposition will mess up seeking. I'm hoping someone can explain why. That seems more like a container issue to me.


It's not a container issue. if you seek within an Opus file, what you decode from that point will not be bit-exact with a decoder that started from the beginning of the file. The difference is so small that it's not audible, but it still means losing the lossless property as soon as you seek.

But really, I think most comments have so far missed the real issue here: A lossless extension to Opus would be mostly pointless. A 48 kHz 16-bit PCM stereo file is 1536 kb/s, and on average a codec like FLAC will compress about 50%, so that means 768 kb/s. If you consider that Opus gives you pretty good quality at 96 kb/s, then it means that Opus+FLAC would cost you 864 kb/s. OTOH, a lossless extension to Opus, would compress slightly worse then than a "native" lossless codec like FLAC (partly due to things like intensity stereo and spectral folding), probably costing us about at *least* 5%, meaning that we'd end up at 806 kb/s. So in the end, we have a messy new extension that saves us only 7% compared to just carrying two sets of files. There's just no point, really. Get over it.

This post has been edited by jmvalin: Feb 25 2013, 05:43
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wswartzendruber
post Feb 25 2013, 06:02
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Your first paragraph raises a very good and valid point. This is a technical issue that I will have to assess.

Your second paragraph, on the other hand, is mainly a matter of philosophy. You also appear to be a bit confused. "We" aren't going to be having any extension. "I" will be having an extension that others will be free to use. I do not require your blessing to continue, nor quite frankly, do I care if I have it. Especially not with that attitude.

I am looking for technical issues. So far, two very good ones have been raised.

This post has been edited by db1989: Feb 25 2013, 11:14
Reason for edit: deleting pointless full quote
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2Bdecided
post Feb 25 2013, 12:23
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QUOTE (jmvalin @ Feb 25 2013, 04:43) *
we have a messy new extension that saves us only 7% compared to just carrying two sets of files.
..and sometimes it's worse, and it's always worse than just a pure lossless file that doesn't depend on a lossy core.

If you must go down that route and want to hack around with something "free", WavPack Hybrid and lossyWAV/lossyFLAC + correction files are built with this in mind.

Cheers,
David.
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Posts in this topic
- wswartzendruber   Lossless Extensions for Opus (Backwards Compatible)   Feb 24 2013, 19:58
- - NullC   QUOTE (wswartzendruber @ Feb 24 2013, 10...   Feb 24 2013, 20:58
|- - Garf   QUOTE (NullC @ Feb 24 2013, 20:58) The op...   Feb 24 2013, 21:09
- - lvqcl   And how to losslessly encode 44.1 kHz audio?   Feb 24 2013, 21:23
|- - Garf   QUOTE (lvqcl @ Feb 24 2013, 21:23) And ho...   Feb 24 2013, 21:25
- - wswartzendruber   When I came up with this idea, my primary use case...   Feb 24 2013, 21:36
|- - saratoga   QUOTE (wswartzendruber @ Feb 24 2013, 15...   Feb 24 2013, 22:08
|- - C.R.Helmrich   QUOTE (wswartzendruber @ Feb 24 2013, 21...   Mar 19 2013, 21:45
- - wswartzendruber   Compatibility with existing Opus decoders.   Feb 24 2013, 22:10
|- - saratoga   QUOTE (wswartzendruber @ Feb 24 2013, 16...   Feb 24 2013, 22:34
|- - wswartzendruber   QUOTE (saratoga @ Feb 24 2013, 17:34) QUO...   Feb 24 2013, 22:43
- - db1989   Which, as has already been explained, is not possi...   Feb 24 2013, 22:14
- - wswartzendruber   Nowhere in this thread has it been explained that ...   Feb 24 2013, 22:21
- - saratoga   Mp3, aac.   Feb 24 2013, 22:54
|- - wswartzendruber   QUOTE (saratoga @ Feb 24 2013, 17:54) Mp3...   Feb 24 2013, 23:00
|- - saratoga   Do you really care? The MP3 patent license is alm...   Feb 25 2013, 00:10
|- - wswartzendruber   mp3HD can't go beyond stereo and 16-bit. I...   Feb 25 2013, 01:32
|- - saratoga   QUOTE (wswartzendruber @ Feb 24 2013, 19...   Feb 25 2013, 01:36
|- - wswartzendruber   QUOTE (saratoga @ Feb 24 2013, 20:36) The...   Feb 25 2013, 01:43
|- - saratoga   There are no existing hybrid lossless decoders for...   Feb 25 2013, 02:54
|- - wswartzendruber   QUOTE (saratoga @ Feb 24 2013, 21:54) The...   Feb 25 2013, 03:10
|- - saratoga   QUOTE (wswartzendruber @ Feb 24 2013, 21...   Feb 25 2013, 20:54
- - wswartzendruber   I also missed the part above where this propositio...   Feb 25 2013, 05:18
|- - jmvalin   QUOTE (wswartzendruber @ Feb 24 2013, 23...   Feb 25 2013, 05:43
|- - wswartzendruber   Your first paragraph raises a very good and valid ...   Feb 25 2013, 06:02
|- - 2Bdecided   QUOTE (jmvalin @ Feb 25 2013, 04:43) we h...   Feb 25 2013, 12:23
|- - jensend   QUOTE (wswartzendruber @ Feb 24 2013, 22...   Feb 25 2013, 20:17
|- - wswartzendruber   QUOTE (jensend @ Feb 25 2013, 15:17) Assu...   Feb 25 2013, 20:48
- - wswartzendruber   Why does DTS-HD have a lossy core stream?   Feb 25 2013, 17:00
|- - 2Bdecided   QUOTE (wswartzendruber @ Feb 25 2013, 16...   Feb 25 2013, 17:17
|- - wswartzendruber   QUOTE (2Bdecided @ Feb 25 2013, 12:17) QU...   Feb 25 2013, 19:22
- - wswartzendruber   I can't really say that I feel motivated to ex...   Feb 25 2013, 21:47
- - Garf   The problem here is on 2 levels: a) Technical one...   Feb 26 2013, 10:50
- - Jplus   wswartzendruber: The very reason that saratoga men...   Feb 26 2013, 13:57
- - wswartzendruber   I knew of an MPEG-4 scheme that involved an AAC tr...   Feb 26 2013, 19:59
|- - saratoga   QUOTE (wswartzendruber @ Feb 26 2013, 13...   Feb 26 2013, 20:54
- - wswartzendruber   I'm looking more towards the future, in terms ...   Feb 26 2013, 21:57
|- - Soap   If your response to saratoga's comments about ...   Feb 26 2013, 22:16
- - Porcus   There is a “tie your hands to commitment...   Feb 27 2013, 00:20
|- - wswartzendruber   QUOTE (Porcus @ Feb 26 2013, 18:20) If yo...   Feb 27 2013, 02:49
|- - saratoga   QUOTE (wswartzendruber @ Feb 26 2013, 20...   Feb 27 2013, 03:22
||- - wswartzendruber   QUOTE (saratoga @ Feb 26 2013, 21:22) QUO...   Feb 27 2013, 03:25
|- - Porcus   QUOTE (wswartzendruber @ Feb 27 2013, 02...   Feb 27 2013, 19:55
|- - wswartzendruber   QUOTE (Porcus @ Feb 27 2013, 13:55) OK, s...   Feb 27 2013, 22:27
|- - Porcus   QUOTE (wswartzendruber @ Feb 27 2013, 22...   Feb 28 2013, 01:07
- - saratoga   It sounding more and more like you're going to...   Feb 27 2013, 03:32
|- - wswartzendruber   QUOTE (saratoga @ Feb 26 2013, 21:32) It ...   Feb 27 2013, 04:06
- - wswartzendruber   World domination is irrelevant. Anyway, I looked ...   Mar 1 2013, 00:52
- - wswartzendruber   OptimFROG is showing promise.   Mar 1 2013, 03:05
- - wswartzendruber   The 1.1 alpha build has further increased the effi...   Mar 15 2013, 04:47
- - wswartzendruber   Crap, I meant to say that I'm going use R5 vio...   Mar 15 2013, 07:13
- - LithosZA   Lossless extensions to Opus would be completely po...   Mar 15 2013, 08:37
- - wswartzendruber   Yeah, I hear you there. I've contacted the Op...   Mar 16 2013, 23:53
- - wswartzendruber   I have heard back from the OptimFROG developer. H...   Mar 19 2013, 04:42
|- - NullC   QUOTE (wswartzendruber @ Mar 18 2013, 20...   Mar 25 2013, 22:28
|- - wswartzendruber   QUOTE (NullC @ Mar 25 2013, 16:28) QUOTE ...   Mar 25 2013, 23:23
|- - jmvalin   QUOTE (wswartzendruber @ Mar 25 2013, 18...   Mar 25 2013, 23:53
|- - Soap   QUOTE (wswartzendruber @ Mar 25 2013, 17...   Mar 25 2013, 23:54
- - wswartzendruber   I solicited Florin for interest in the project and...   Mar 20 2013, 01:12
- - wswartzendruber   I am no longer seeking to use Opus padding. I now...   Mar 26 2013, 00:44
|- - jmvalin   QUOTE (wswartzendruber @ Mar 25 2013, 19...   Mar 26 2013, 00:55
||- - wswartzendruber   QUOTE (jmvalin @ Mar 25 2013, 18:55) QUOT...   Mar 26 2013, 03:53
||- - jmvalin   QUOTE (wswartzendruber @ Mar 25 2013, 22...   Mar 26 2013, 04:47
|- - Soap   QUOTE (wswartzendruber @ Mar 25 2013, 18...   Mar 26 2013, 01:15
- - 2Bdecided   I wonder why you've chosen opus? Rather than a...   Mar 26 2013, 10:35
- - wswartzendruber   MP3 stops at stereo. Besides that, there is alrea...   Mar 26 2013, 20:59
|- - db1989   QUOTE (wswartzendruber @ Mar 26 2013, 19...   Mar 26 2013, 21:04
- - wswartzendruber   First off, mp3 Surround (which I would hypothetica...   Mar 27 2013, 02:26
|- - saratoga   QUOTE (wswartzendruber @ Mar 26 2013, 20...   Mar 27 2013, 02:52
|- - Soap   QUOTE (saratoga @ Mar 26 2013, 20:52) MP3...   Mar 27 2013, 02:57
- - saratoga   Actually I suppose if the goal is to have this wor...   Mar 27 2013, 03:02
- - wswartzendruber   I see that reiteration is necessary. 1. I have no...   Mar 27 2013, 04:08
|- - saratoga   QUOTE (wswartzendruber @ Mar 26 2013, 22...   Mar 27 2013, 04:23
- - wswartzendruber   1. I am not out to extend OptimFROG, I'm out t...   Mar 27 2013, 04:44
- - wswartzendruber   I sent Florin one last email asking for input. If...   Mar 29 2013, 04:37
|- - C.R.Helmrich   QUOTE (wswartzendruber @ Mar 29 2013, 04...   Mar 29 2013, 15:10
- - wswartzendruber   I'll just use this thread as sort of a log. A...   Mar 30 2013, 22:58
- - Dynamic   With mention of an open lossy codec being a requir...   Mar 31 2013, 10:54
- - Destroid   Dynamic's suggestion is very interesting. In a...   Mar 31 2013, 11:55
- - wswartzendruber   One of the main reasons for choosing Opus is becau...   Mar 31 2013, 15:40
- - wswartzendruber   Florin got back to me. He's just in a bit of ...   Apr 1 2013, 22:52
- - wswartzendruber   One week, right. I think he's in a bit more o...   Apr 19 2013, 06:38
- - wswartzendruber   QUOTE (wswartzendruber @ Apr 19 2013, 01...   Aug 9 2013, 22:24
- - wswartzendruber   Florin finally got back to me! He's been ...   Nov 30 2013, 21:08


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