LPCM multichannel possible on DVD-Video?

[daphy]

Hi folks,

I´ve found an interesting site (http://www.mpeg.org/MPEG/DVD/Book_B/Audio.html), which claim that uncompressed multichannel should be possible on a DVD-Video. Obviously it depends on the over all sampling rate (Video + all soundtracks) below 9.8MB/s.

Has someone experiences with that?
What is the right channelmapping (L,R,C,LFE,SL,SR = 6 -> 5 or 8 should be possible at 48KHz)?
Am I right in thinking that this must be one big multichannel WAV?
What authoring software is recommendable for this exercise (I´ll guess most will refuse a 6 channel WAV and up?

I never tried a multichannel - what I´ve already tried is a two channel with 96KHz. But my player refused to send the 96KHz signal to the amp. instead he downsampled it to 48KHz :devil: (maybe this depends on SPDIF limitations :confused: )

PLZ remember: we´re talking about DVD-VIDEO not DVD-AUDIO


THX ;)

PS: this theme is simular to this thread (http://forum.doom9.org/showthread.php?t=100121) :o

[Rockaria]

I also found an interesting article (http://www.surroundassociates.com/newformats.html) on both DVD-A & DVD-V, somewhat old(dates back to 1999) though, after the discussions on that thread.
The LPCM bit stream, which is the same uncompressed format as today's Red Book CD (which is standardized at 44.1kHz and 16 bit), can use either a 48 or 96kHz sample rate with a bit depth of either 16, 20 or 24 bits. Now on the surface this seems great and makes you wonder why another format for multichannel audio is even considered, but then you realize that the bit rate for the audio data is capped at 6.144Mbps. As for the lossless format, the DVD-A's standard MLP(Meridian Lossless Packing : upto 1.85 / 1 compression) looks more attractive than the compressionless LPCM.
BTW, as for the SPDIF bandwidth on PC platform seems restricted by the spec of the codec's spdif transmitter(out) which is mostly built for 48(44)k 16bit stereo(1411~1532kbps) streams, but still covering the lossy DTS & AC3 stream though.

[daphy]

do you know whether the bandwidth of a coaxial connection differs to SPDIF (or is it just the same)?

[johnman]

Maybe this is old news, but if i play 96khz stereo on coax, my reciever really picks up 96khz :). Now im trying to send it multichannel sound, but so far no succes :(


EDIT its the coax from my soundcard, not my dvd-player.

EDIT2 I think it might be possible to send multichannel sound through coax, but my reciever chokes on it. I tried 22 khz 16 bits 6 channel wav, and when i play it with foobar i hear all sound mixed thorugh the front speakers, and when i play it in winamp, i hear only FL and FR . In both cases hower my reciever states its receiving 96 khz DVD, which i think is always shown when it doenst get the normal formats. But this does mean my receiver doesnt receive the normal 44khz stereo format when i send it 96khz

[daphy]

okay, I will check this immediately THX :)

[Rockaria]

do you know whether the bandwidth of a coaxial connection differs to SPDIF (or is it just the same)?Considering the USB2.0 doing 480mbps with one or two data lines, I think the carrier itself is not the big factor.
The codec has the spdif in/out controller specification limiting the spdif transmition layer bandwidth, I guess.

[johnman]

I just browsed in the manual of my soundcard and i found something interesting:

I have 2 modes for digital output, "CD" and "DMA". It seemes when i select the CD mode it only outputs digitally when i send the normal audio formats to the output, and when i use the DMA mode is sends out everything. (also multichannel i think, but i cant check this :( )


DMA is for internal dataoutput and CD is pass thru S/PDIF signal from CD-digital input on CD –digital in connector.


So what i tried earlier might not work on all coax outputs.

[daphy]

(from the other thread (http://forum.doom9.org/showthread.php?p=714238#post714238))
seems you might be right.. at 48khz S/PDIF has a bitrate of 3.1 Mbits/s.

A 5.1 LPCM stream would atleast be (overhead have to be added)
samplerate bits ch
48000 * 16 * 6 = 4608000

ie about 4.6 Mbits per second.... crap again

Maybe this is old news, but if i play 96khz stereo on coax, my reciever really picks up 96khz . Now im trying to send it multichannel sound, but so far no succes

let´s see:
96000 * 24 * 2 = 4608000 on coax :eek: ;) :D

[johnman]

let´s see:
96000 * 24 * 2 = 4608000 on coax :eek: ;) :D

So what i tried earlier might not work on all coax outputs. ;)


Im now playing a 96000 hz * 24 bits * 2 channel file with foobar, (my soundcard and receiver confirming its playing @ 96khz) and all i can say is that i plays on digital out and it sounds fine. I think the soundcard isnt following the spdif limitations in DMA mode so that could explain why I can do this.

[Rockaria]

So your card is doing the 4.6mbps on coax. ;) But what kind of a sound card can do the multichannel spdif output without encoding to any supported formats? :confused:
Direct memory access (DMA) allows certain hardware subsystems within a computer to access system memory for reading and/or writing independently of the CPU. Many hardware systems use DMA including disk drive controllers, graphics cards, network cards, and sound cards.
Considering the DMA is for internal uses, I guess the card has a wide band cable pins on it to connect to another similar sound card internally.

[johnman]

So your card is doing the 4.6mbps on coax. ;)

You dont have to believe me, but if my soundcard is saying it sends 96khz and my receiver (which supports 96khz/24bits) is showing its receiving @ 96khz, im pretty sure it is.

When i play multichannel, i dont know what my soundcard sends on the coax, but it is sending something which my receiver doesnt realy "understand". I dont know what it sends, but i dont know a reason why i cant send a multichannel wav through coax. Its just data, only a bit more then normally. Even if no normal receiver supports it, it can still be possible right? :confused: :confused: :confused: . If you have a good cable, i dont think there is a physical limitation to send more then 3.1 Mbps


Considering the DMA is for internal uses, I guess the card has a wide band cable pins on it to connect to another similar sound card internally.


Maybe i dont understand you, but its the DMA mode for the (coax and maybe optical) digital output. I cant plugin a ide cable (or similair) on my soundcard :D

[Rockaria]

You dont have to believe me,I believe your sound card supports 4.6mbps spdif out. What is your card?

[johnman]

I believe your sound card supports 4.6mbps spdif out. What is your card?

Audiotrak Prodigy 7.1 LT. (http://www.audiotrak.net/prodigy7.1LT.htm)


(Although its recomended by a lot of people on HA, i wouldnt buy it again if i had the choice. There is basicly no development on the drivers, although its needed very much. Before buying this one, look @ the forum of audiotrack. Many complaints :(. I heard the Audiotak Prodigy 7.1 (without LT) is a lot better, but that one cant be bought in my country, so i went for the LT instead :(.

im just warning in case ppl are thinking about buying it)


EDIT: daphy did you have any succes with 96khz?

[Rockaria]

Wow, it's one of a professional cards by the spec(9.2mbps on coax!). :eek:
Latest ICE1722/1724 (ENVY24GT/HT) Controller
Optical (24-bit/96kHz) and Coaxial (24-bit/192kHz) The early mentioned CD/DMA mode seems to be cd-in spdif passthru vs. front pcm routing to the spdif transmitter.
It cannot support multi channel spdif out without live encoding...
Btw, the DirectWire feature looks interesting.

[johnman]

Wow, it's one of a professional cards by the spec(9.2mbps on coax!). :eek:
The early mentioned CD/DMA mode seems to be cd-in spdif passthru vs. front pcm routing to the spdif transmitter.


Thx for looking it up :).
Althoug the specs are cool, the drivers arent. I cant use the digital output for watching dvd's. The signal goes on and off every 0.3 seconds. So i have to watch my movies with analogue stereo sound :(. And sometimes everything is working fine excepts i dont get any sound on the analog output, even though the level meters show that there is sound.


It cannot support multi channel spdif out without live encoding...


OK, so when i play a multichannel wav it should only send the front left and right? This doesnt always happen, but i guess this might be caused by the playing software, or the drivers even since these arent the best in the world.


Btw, the DirectWire feature looks interesting.
That was one of the reasons i bought it :).

Thx for clearing it up :goodpost:

[daphy]

Hiho,

I tried a 6-channel 16bit 48KHz WAV with DVDLab, no sucess. It recognized the WAV as good but stopped while compiling the DVD. I will give ém another try later before I switch to anoth authoring program :(

[SeeMoreDigital]

A few months ago I used MuxMan to create a full VOB set from a 60 second 720x576 MPEG-2 video file with an 60 second 6Ch WAV 4608Kbps/48kHz/16bit audio file......

Using my Pioneer DVD player I was able to play the full VOB set, but in order to hear the audio mapped correctly I had to use my players and DSS amps analogue connections....


Cheers

[daphy]

THX SeeMoreDigital for confirming!

Meanwhile I did another test on a 6WAV with DVDlab, this time it worked with the analogue connectors -> SPDIF definitvly doesn´t handle this bandwith. Next I have to check is a coaxial connection between standalone DVD-Player and amp :o

... to be continued ...

BTW: if this works - why fooling around with some DVD-Audio stuff when you get something more compatible ;)

[daphy]

sorry folks,

also here (try with two standalones) no chance to replay a 6WAV16/48 via coaxial :mad: :(

the thing that excites me the most is the fact that it´s a part of the standard which should definitvly work! :devil:

Maybe I did something wrong ... :confused:

[SeeMoreDigital]

THX SeeMoreDigital for confirming!

Meanwhile I did another test on a 6WAV with DVDlab, this time it worked with the analogue connectors -> SPDIF definitvly doesn´t handle this bandwith. Next I have to check is a coaxial connection between standalone DVD-Player and amp :o

... to be continued ... For me it does not matter which S/PDIF connection I use, I can only make it work via analogue. Same goes for DVD-Audio and SACD streams too!

I've also been experimenting with 6Ch Vorbis (in .OGG), which might prove promising, seeing as though I can play this using my Pioneer player as-well.


Cheers

[daphy]

My amp (SPDIF or coaxial) recognizes the PCM only as 2.0 - the DVD-Player as multichannel :(
analogue as you said before it works fine, I will do another test with 96KHz 2.0, let´s seen what´ll happen then ...

[SeeMoreDigital]

While where on the subject of 6Ch audio streams....

I wonder if somebody here could convert a 6Ch AC3 stream to a 6Ch DTS stream for me please?

If you can, please PM me and I'll provide a link to the (6Ch speaker mapping) AC3 stream I require converting.


Cheers

[daphy]

Final test 16/96KHz 2.0 failed, too. The same situation -> the PCM Stream would only be recognized as 16/48 2.0 - I´ll give up at this point :sly:

If someone has more succsess, plz report :o

[Rockaria]

At least the multi channel stream header & content must be reorganized to LPCM if the decoder supports it as is inquired in the original thread, imo.
That is we must rely on a dynamic soft ac3/dts/lpcm encoder(with possibly dynamic resampling to 48k) in a format of plugin or dsfilter to toss the stream to the spdif transmitter(to simulate the pass through), or rely on the genuine digital sound cards such as soundstorm(5.1 ac3) or recent expensive 7.1ch cards with h/w based live encoding for external digital receivers.

[planet1]

Apparently discrete multichannel sound wasnt much of an issue back in the early 90s.
And using digital connections for such even less :sly: .

http://en.wikipedia.org/wiki/SPDIF (4 channels :confused: )

But thx to DVD-Audio - connections improved as well.

http://en.wikipedia.org/wiki/Ilink (aka FireWire, IEEE 1394)
http://en.wikipedia.org/wiki/HDMI

Although 3 coaxial/optical connectors could have done it as well ;) , but then the studios calls for Content Protection features would have gone unanswered.

Just in case someone with a new fancy DVD-Audio player is with us:
I wonder if those new connectors work under DVD-Video mode as well (multichannel LPCM).
Either create your own test DVD-R(W) with e.g. MuxMan or use jsoto's sample DVD http://forum.doom9.org/showthread.php?p=603581#post603581.

cya :cool:

[Rockaria]

The IEC958 standard (http://www.epanorama.net/documents/audio/spdif.html) is OLD or does not reflect today's high-end digital audio requirements and implementations in the DESCRIPTIONs.
Practically many receivers support 24 x 96(4.6mbps) or 24x 192(9.2mbps) as many professional bit accurate(no-down-sampling to 48k) sound cards do.
The reality is that most onboard ac97 spdif specs are capped out at 24bit x 48khz at best and 16 x 48 normally.

There had been creative's now-hard-to-find digital din solution for multi channel pcm digital out for their specific digital speakers(i.e. fsp2000). But they are limited by the number of the data lines and is not industry standard.
Also imbeding compressed/non-compressed multichannel streams in the dvd is proved possible. But the ability of spdif transfer is another question(by the bandwidth and devices' spec).

So my conclusion so far is that the SPDIF bandwidth is capable of up to 24 x 192 in stereo(9.2mbps) depending on the devices' spdif spec and the cabling(surprisingly, the high end coaxial cable is regarded twice better than the optical as seen in the Audiotrak's spec).

http://www.hydrogenaudio.org/forums/index.php?showtopic=19020#