search for: uhj

Michael Graczyk wrote: ... > UHJ is an interesting way to preserve compatibility with non-ambisonic > playback systems. ... > If UHJ becomes popular in the future, we could > specify rules for encapsulating UHJ in Ogg. I guess it depends on how you define popular. The UHJ Discography lists over 270 UHJ-encoded records....

On Tue, 31 May 2016 09:41:37 -0700 Michael Graczyk <mgraczyk at google.com> wrote: > UHJ is an interesting way to preserve compatibility with non-ambisonic > playback systems. However, I have not seen it generalized to higher > orders. I expect that its popularity will decrease as HOA becomes more > and more common. If UHJ becomes popular in the future, we could > specify r...

...n interest for "VR" (which is why Ambisonics is becoming popular). Horizontal HOA needs 5 channels for 2nd order, one channel less than 5.1! Using the extra channel adds FOA vertical information, for a much better experience than plain 5.1. I would suggest to also include support for the UHJ format, which is roughly equivalent to 3 channels FOA, but using only 2 channels; even soundfield rotation is possible with UHJ (although less good), enabling horizontal "VR audio" with only 2 channels. Ok, enough proselytism... VR+Ambisonics+Opus is a winning combination. -- Marc

...just to see what support was there (if any). ... > I do not believe that there is any need for code specifically > supporting Ambisonics. FLAC supports conversion to and from other > audio formats which hold multiple channels. Ambisonics B-format > involves channels WXYZ, C-format is UHJ or BHJ, G-Format can be any > number of channels, but typically 5.1 on DVD. You can work with > Ambisonic recordings by either using individual mono files for each > of the Ambisonic channels, or by using a 4-channel or 6-channel > AIFF. All of these files can be compressed into FLAC...

...utput schemes like 5.1, because it would be like putting a square > peg in a round hole; decoding Ambisonics for irregular arrays can be an > art form, it's not like working with common surround formats. Thanks for the input. I agree. > I would suggest to also include support for the UHJ format, which is > roughly equivalent to 3 channels FOA, but using only 2 channels; even > soundfield rotation is possible with UHJ (although less good), enabling > horizontal "VR audio" with only 2 channels. UHJ is an interesting way to preserve compatibility with non-ambisonic...

...B-format audio (via the panner or directly input) into Ogg/Vorbis brings an interesting challenge: What do we do with the audio after decoding it? The following sane options exist: A) Simply output the B-format audio B) Produce a downmix 1) Mono. 2) Stereo blumlein crossed pairs 3) Stereo UHJ 4) binaural C) Produce speaker feeds 1) Fully generalizable speaker feed decoder (such as http://www.kokkinizita.net/linuxaudio/adec-pict.html) 2) G-format (fixed decode for the 5.1 layout) (A) is pretty much a no-brainer, and minus some polish on marking up the channel mapping we pret...

Hi, I have posted this three times to the flac-dev, vorbis-dev, and ogg-dev mailing lists. I wanted to see what code there was currently to support Ambisonics. So I downloaded the code from the xiph download page for libogg-1.1.3, libvorbis-1.1.2, vorbis-tools-1.1.1 and flac-1.1.4, but wasn't able to find anything. If it exists then I missed it, so could somebody please point me to it.

>Yesterday I have finished writing the ambisonic pan filter for oggenc. May I ask what this "pan filter" is? I made some tentative suggestions for coupling Ambisonic B-format in a post "Vorbis Ambisonic coupling" on 4feb07 I gather from the last monthly meeting, that some of you, including Monty, had problems with the phase behaviour of B-format. Would anyone like a

...ferent channel profiles for 5.1: L R C LFE Ls Rs (DVD) L R Ls Rs C LFE L C R Ls Rs LFE (Film) then we have ambisonics where we have 1st, 2nd and 3rd order (4, 9 and 16 channels), but then you can also have 2 dimensional ambisonics without heigt signal, which gives another 3 options, plus different UHJ encoded variants, etc. how can we squeeze this in 4 bits?

...nels. However, in this case, the metadata should not be in the FLAC stream(s) but in the Ogg container. There is no simple way to do this, but possibilities include name-value pairs in an Ogg Skeleton stream and a XMLEmbedding stream.(9) Finally, your proposal only considers Ambisonic B-Format. UHJ and G-Format are also part of Ambisonics. There is an official file format for UHJ,(10) and a proposal for G-Format.(11) UHJ could be accommodated into your proposal quite simply using the VorbisComment "AMBISONIC:UHJ". G-Format is a lot more complicated, and should probably be ignored....

...inputs your sending it to, depending on how that set of inputs is configured. > then we have ambisonics where we have 1st, 2nd and 3rd order (4, 9 and > 16 channels), but then you can also have 2 dimensional ambisonics > without heigt signal, which gives another 3 options, plus different UHJ > encoded variants, etc. Well, we already have the problem of being able to encode only a very limited number of independent tracks in this field, too. Currently the limit is 8, which does me no good when I want to FLAC-encode a multi-track "master" from my studio, which can easily be...

...(eg the Chesky's) I don't think we should look down on simple Blumlein. The 3 good stereo downmixes are - Blumlein fig-8s at 90. Probably best for loudspeaker stereo - Back to Back cardioids. This is best for simple binauaral. With Y increased by up to 3 dB good for speakers too. - UHJ stereo : The most complicated cos long FIRs required. Each of these will sound better under certain conditions and I would personally want all 3. But if you asked me which to ditch, the obvious one to throw out is UHJ. The Vorbis "decoder" defaults to either Blumlein or Back to Back Ca...

...flexible approach than only defining 16 different channel mappings. >>then we have ambisonics where we have 1st, 2nd and 3rd order (4, 9 and >>16 channels), but then you can also have 2 dimensional ambisonics >>without heigt signal, which gives another 3 options, plus different UHJ >>encoded variants, etc. > > > Well, we already have the problem of being able to encode only a very > limited number of independent tracks in this field, too. Currently > the limit is 8, which does me no good when I want to FLAC-encode a > multi-track "master" f...

...se you too much -- read some of the articles on the site I gave earlier for more in-depth information), I'll describe more specifically what I have in mind for the Ogg project. First of all, though there are several formats currently in use for distributing Ambisonic material (including one -- UHJ -- which is stereo compatible) I propose that we use Ambisonic B-format (using the harmonics directly -- we would have W, X, Y, etc. channels in the Ogg stream), as it is the easiest to decode (if we used another format like UHJ, the player would have to decode it to B-format before it could do mor...

...ome of the articles on the site I gave > earlier for more in-depth information), I'll describe more specifically what > I have in mind for the Ogg project. > > First of all, though there are several formats currently in use for > distributing Ambisonic material (including one -- UHJ -- which is stereo > compatible) I propose that we use Ambisonic B-format (using the harmonics > directly -- we would have W, X, Y, etc. channels in the Ogg stream), as it > is the easiest to decode (if we used another format like UHJ, the player > would have to decode it to B-format be...

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

...se you too much -- read some of the articles on the site I gave earlier for more in-depth information), I'll describe more specifically what I have in mind for the Ogg project. First of all, though there are several formats currently in use for distributing Ambisonic material (including one -- UHJ -- which is stereo compatible) I propose that we use Ambisonic B-format (using the harmonics directly -- we would have W, X, Y, etc. channels in the Ogg stream), as it is the easiest to decode (if we used another format like UHJ, the player would have to decode it to B-format before it could do mor...

Martin, I do not believe that there is any need for code specifically supporting Ambisonics. FLAC supports conversion to and from other audio formats which hold multiple channels. Ambisonics B-format involves channels WXYZ, C-format is UHJ or BHJ, G-Format can be any number of channels, but typically 5.1 on DVD. You can work with Ambisonic recordings by either using individual mono files for each of the Ambisonic channels, or by using a 4-channel or 6-channel AIFF. All of these files can be compressed into FLAC and expanded...

...(there are a number >> of different formats like 5.1 and 7.1) or quadraphonic? How >> are you going to specify which channel is which. Being able to >> encode this stuff easily is **vital**. > > > please don't forget ambisonics :-) > > 2 channel UHJ > 4 channel 1st order > 9 channel 2nd order > 16 channel 3rd order > > etc. > _______________________________________________ > ogg-dev mailing list > ogg-dev@xiph.org > http://lists.xiph.org/mailman/listinfo/ogg-dev

i didn't find anything about tagging flac files as surround files. i think there should some possibility to tell the player how to play a multi-channel file (how to map the different channels to the speakers or if there some decode is needed, like for ambisonic files). any idea how to implement it?