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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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Dynamic
post Mar 31 2013, 10:54
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With mention of an open lossy codec being a requirement, the other option is Ogg Vorbis, which supports specific sampling rates and isn't too far behind Opus in bitrate efficiency and is an open format that has fairly widespread support in the wild (main exception being Apple, despite Wikipedia's use of Vorbis). Then you have no worry about resampling consistently so that the hybrid remains lossless. You then just need to presumably place non-Vorbis packets in the Ogg stream that all Vorbis decoders (except your hybrid decoder) will ignore. Presumably it would also be easy to strip out only Vorbis packets from the Ogg stream to obtain a smaller lossy file.

The other option where sampling rate can be specified and still be expected to play is Xiph.org's CELT (forerunner to the CELT half of Opus you're thinking of), but plain CELT decoder support in the wild is very limited and will very likely remain so now Opus has superceded it, even though I believe Google's plugin for Chat/Hangouts uses CELT in its new Studio mode (click Learn More in this link) and will possibly implement Opus in due course, possibly piggybacking on WebRTC integration.

On the positive side for Opus, it's possible that being standardized by IETF with clearly specified open patent licensing, support will eventually surpass that of Vorbis.
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- 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
- - darkbyte   This stuff died quickly. Nevertheless i wonder w...   Aug 7 2014, 10:52
|- - wswartzendruber   QUOTE (darkbyte @ Aug 7 2014, 05:52) This...   Aug 7 2014, 14:09
|- - saratoga   QUOTE (darkbyte @ Aug 7 2014, 05:52) This...   Aug 7 2014, 19:28
|- - 2Bdecided   QUOTE (darkbyte @ Aug 7 2014, 10:52) Most...   Aug 12 2014, 13:41
|- - skamp   QUOTE (2Bdecided @ Aug 12 2014, 14:41) If...   Aug 12 2014, 14:03
|- - wswartzendruber   QUOTE (2Bdecided @ Aug 12 2014, 07:41) As...   Sep 6 2014, 18:03
|- - wswartzendruber   Good grief. Firefox can't even handle packets...   Sep 6 2014, 19:56
|- - wswartzendruber   Apparently editing posts has some kind of expirati...   Sep 7 2014, 00:01
- - darkbyte   Okay sorry, it's just there was no update for ...   Aug 7 2014, 14:35
|- - wswartzendruber   I've already decided on using the same contain...   Aug 7 2014, 19:13
|- - jmvalin   QUOTE (wswartzendruber @ Aug 7 2014, 14:1...   Aug 7 2014, 19:34
|- - wswartzendruber   QUOTE (jmvalin @ Aug 7 2014, 14:34) So wh...   Aug 7 2014, 20:07
|- - jmvalin   QUOTE (wswartzendruber @ Aug 7 2014, 15:0...   Aug 11 2014, 19:10
|- - skamp   QUOTE (jmvalin @ Aug 11 2014, 20:10) QUOT...   Aug 11 2014, 20:13
- - saratoga   I think people generally expect poorly thought out...   Aug 7 2014, 20:12
- - wswartzendruber   Well, none of the players I've tested are fall...   Sep 6 2014, 17:58
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