search for: sn3d

...225. Ambisonics from first to fifteenth order. Each channel is assigned to an ambisonic component in Ambisonic Channel Number (ACN) order. The ambisonic component with degree n and ambisonic index m corresponds to channel (n * (n + 1) + m). Channels are normalized with Schmidt Semi-Normalization (SN3D). In SN3D, the ambisonic component of degree n and index m is normalized according to sqrt((2 - delta(m)) * ((l - m)! / (l + m)!)), where delta(0) = 1 and delta(m) = 0 otherwise. ------ I chose ACN order and SN3D normalization because these seem to be the most common, and are used by the Ambix for...

I compiled the latest (git master) of opus, libopusenc, opusfile and opus-tools: $ opusenc --version opusenc opus-tools 0.2-8-g4976421 (using libopus 1.3.1-4-gad8fe90d) I tried to encode a 3rd order Ambisonics wav file with the standard Ambix (ACN-SN3D) format; opusinfo is reporting : Streams: 16, Coupled: 0     Channel Mapping Family: 255 Map: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15] How to encode the file so that the Mapping Family is 3, as suggested here ? : https://people.xiph.org/~jm/opus/opus-1.3/ Marc

On 19/04/16 12:17 PM, Timothy B. Terriberry wrote: > We should probably start keeping track of the space of invalid TOC > sequences somewhere global so that people don't define conflicting > extensions. I started such a page at https://wiki.xiph.org/OpusExtensions -r -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type:

Hi Opus list. I subscribed because your discussion on the IETF draft ("Ambisonics in an Ogg Opus Container") was mentioned on the sursound list. I tried Opus for ambisonics more than a year ago. It does works with uncoupled channels (I had to patch the encoder). I don't know what else could be done to optimize support for ambisonics, as I'm not a codec expert. So I think that

...ompiled the latest (git master) of opus, libopusenc, opusfile and > opus-tools: > > $ opusenc --version > opusenc opus-tools 0.2-8-g4976421 (using libopus 1.3.1-4-gad8fe90d) > > I tried to encode a 3rd order Ambisonics wav file with the standard > Ambix (ACN-SN3D) format; opusinfo is reporting : > > Streams: 16, Coupled: 0 >     Channel Mapping Family: 255 Map: [0, 1, 2, 3, 4, 5, 6, 7, 8, > 9, 10, > 11, 12, 13, 14, 15] > > How to encode the file so that the Mapping Family is 3, as suggested > here ? : https://...

...25. Ambisonics from first to fifteenth order. Each channel is assigned to an ambisonic component in Ambisonic Channel Number (ACN) order. The ambisonic component with degree n and ambisonic index m corresponds to channel (n * (n + 1) + m). Channels are normalized with Schmidt Semi-Normalization (SN3D). In SN3D, the spherical harmonic of degree n and index m is normalized according to sqrt((2 - delta(m)) * ((l - m)! / (l + m)!)), where delta(0) = 1 and delta(m) = 0 otherwise. The interpretation of the ambisonics signal as well as the channel order and normalization are described in [ambix]. ---...

...mbix format was adopted by Google, but it's a new format; > the FuMa format is widely used and could easily be supported as well. > https://en.wikipedia.org/wiki/Ambisonic_data_exchange_formats Although FuMa conventions are commonly used, the ambix conventions of ACN channel ordering and SN3D normalization are increasingly becoming the norm. FuMa generally uses maxN normalization, which becomes complicated for fourth order and above. I decided to require ACN and SN3D to limit fracturing and potential confusion. > Down-mixing to stereo is a sort of ambisonic decoding; it is simple an...

...For these kinds of things, you can just use references. > > > Yes, hopefully this is all well-described somewhere (at least enough for > someone to implement it), so we don't have to reinvent the wheel. > I will include a reference to the Ambix paper, which describes ambisonics, SN3D normalization, and ACN channel order. >>> 2. Do I need to list the specific meaning of each possible channel >>> count? For example, should I write "4 channels: First order >>> ambisonics" similar to what is done for surround sound? >> >> >> I...

...ed by channel mapping families 1 and 255. Each output channel is assigned to an ambisonic component in Ambisonic Channel Number (ACN) order. The ambisonic component with degree n and ambisonic index m corresponds to channel (n * (n + 1) + m). Channels are normalized with Schmidt Semi-Normalization (SN3D) with no Condon-Shortley phase factor. In SN3D, the spherical harmonic of degree n and index m is normalized according to </t> <figure align="center"> <artwork align="center"><![CDATA[ sqrt((2 - delta(m)) * ((l - m)! / (l + m)!)), ]]></artwork> &lt...

Tim, Would you mind giving me a more specific example of the sort of document that you think this should look like? I'd like to write up something that is somewhat final. On Mon, May 2, 2016 at 9:30 PM, Michael Graczyk <mgraczyk at google.com> wrote: > On Fri, Apr 29, 2016 at 4:32 PM, Timothy B. Terriberry > <tterribe at xiph.org> wrote: > > As a general point,

...for a channel with index k. </t> <figure align="center"> <artwork align="center"><![CDATA[ order n = ceil(sqrt(k)) - 1, degree m = k - n * (n + 1). ]]></artwork> </figure> <t> Channels are normalized with Schmidt Semi-Normalization (SN3D) with no Condon-Shortley phase factor. In SN3D, the spherical harmonic of order n and degree m is normalized according to </t> <figure align="center"> <artwork align="center"><![CDATA[ sqrt((2 - delta(m)) * ((n - m)! / (n + m)!)), ]]></artwork> &lt...

...the latest (git master) of opus, libopusenc, opusfile and >> opus-tools: >> >> $ opusenc --version >> opusenc opus-tools 0.2-8-g4976421 (using libopus 1.3.1-4-gad8fe90d) >> >> I tried to encode a 3rd order Ambisonics wav file with the standard >> Ambix (ACN-SN3D) format; opusinfo is reporting : >> >> Streams: 16, Coupled: 0 >> Channel Mapping Family: 255 Map: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, >> 11, 12, 13, 14, 15] >> >> How to encode the file so that the Mapping Family is 3, as suggested >> here ? : https://p...

...y Google, but it's a new format; > > the FuMa format is widely used and could easily be supported as > > well. https://en.wikipedia.org/wiki/Ambisonic_data_exchange_formats > > Although FuMa conventions are commonly used, the ambix conventions of > ACN channel ordering and SN3D normalization are increasingly becoming > the norm. FuMa generally uses maxN normalization, which becomes > complicated for fourth order and above. I decided to require ACN and > SN3D to limit fracturing and potential confusion. I understand your point, and content creators will simply co...

...ment: AMBISONIC=(3,0):N3D The above tag defines a 2D planar file with "third order ambisonics" and no height at all, using the N3D normalization scheme. Thus, when a decoder sees this, it knows this file has 7 channels and they are ACN 0,1,3,4,8,9,15. The following tag: AMBISONIC=(3,3):SN3D defines a full-sphere 3D field using the SN3D normalization scheme. When the decoder sees it, it knows the file has 16 channels, them being ACN 0...15. (of course the decoder can refuse to decode if it cannot! that's beside the point!) Would acknowledging such a tag as official format be much...

...gt; wrote: > I compiled the latest (git master) of opus, libopusenc, opusfile and > opus-tools: > > $ opusenc --version > opusenc opus-tools 0.2-8-g4976421 (using libopus 1.3.1-4-gad8fe90d) > > I tried to encode a 3rd order Ambisonics wav file with the standard > Ambix (ACN-SN3D) format; opusinfo is reporting : > > Streams: 16, Coupled: 0 > Channel Mapping Family: 255 Map: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, > 11, 12, 13, 14, 15] > > How to encode the file so that the Mapping Family is 3, as suggested > here ? : https://people.xiph.org/~jm/opus/opus...

...er) of opus, libopusenc, opusfile and >> opus-tools: >> >> $ opusenc --version >> opusenc opus-tools 0.2-8-g4976421 (using libopus 1.3.1-4-gad8fe90d) >> >> I tried to encode a 3rd order Ambisonics wav file with the standard >> Ambix (ACN-SN3D) format; opusinfo is reporting : >> >> Streams: 16, Coupled: 0 >>     Channel Mapping Family: 255 Map: [0, 1, 2, 3, 4, 5, 6, 7, 8, >> 9, 10, >> 11, 12, 13, 14, 15] >> >> How to encode the file so that the Mapping Family is 3, as suggeste...

...x), 609.2ms (avg), 100.0ms (min) Total data length: 8535952 bytes (overhead: 0.466%) Playback length: 1m:25.885s Average bitrate: 795.1 kbit/s, w/o overhead: 791.4 kbit/s Logical stream 1 ended So the goal is to have this 4-channel Ambisonics track ("Ambix" ACN SN3D format, first order) with 2-channel "head locked" Stereo (total of 6 channels) encoded to opus, (and muxed to mp4), so YouTube understands it and - more important - a WebVR Chrome App. Any encoding guide, further Opus + Ambisonics documentation would help, especially as YouTube mentions...

...channels. > > If the user will have to manually specify some command line option, it > seems like an option that explicitly overrides the meaning of the > input channels, like "--channels ambix" to specify that the input > channels are Ambix-compatible channels (ACN order, SN3D normalization) > would be preferable to overriding the mapping family number of the > output. Besides being cryptic, setting a mapping family number > directly is more likely to mislead the user into thinking that the > option affects only the mapping family number that is written in t...

...gt; The above tag defines a 2D planar file with "third order ambisonics" and no > height at all, using the N3D normalization scheme. Thus, when a decoder sees > this, it knows this file has 7 channels and they are ACN 0,1,3,4,8,9,15. The > following tag: > > AMBISONIC=(3,3):SN3D > > defines a full-sphere 3D field using the SN3D normalization scheme. When the > decoder sees it, it knows the file has 16 channels, them being ACN 0...15. > (of course the decoder can refuse to decode if it cannot! that's beside the > point!) > > Would acknowledging such...

Friendly ping for the opus-tools patch... ---------- Forwarded message --------- From: Drew Allen <bitllama at google.com> Date: Mon, Mar 19, 2018 at 2:53 PM Subject: Re: [PATCH] Support for Ambisonics To: opus at xiph.org <opus at xiph.org> On Mon, Mar 19, 2018 at 11:52 AM Drew Allen <bitllama at google.com> wrote: > Hello all, > > Sorry for the delay (got really