ac3 5.1 issues playing xvid

[poisson]

I've been trying to play an xvid file (AVI ext.) containing ac3 5.1 audio, straight from my PC directly to a Hitachi plasma screen with audio going via firewire to a RME Fireface 800 then via SPDIF to a Sony STR-VA555ES amp.

The file's resolution is 960 x 528. I've done a codec "scan" on it with Gspot, Auto GK & AVIcodec. All confirm that video = xvid. Audio = "448 Kbps, 48000 Hz, 2 channels, 0x2000 = AC-3 ACM Decompressor".

My audio problem is, I can't seem to get the PC, RME or/and the Sony to "see" the "5.1-ness" of the file. The Sony amp streams it as linear PCM and just gives me L, R, and Sub.
Generally I KNOW I don't have an issue with 5.1 as there are no problems when playing VOB files for example. Also, I burnt the xvid file to DVD then popped the DVD into a MPEG4 capable DVD player (Zensonic Z340) and although because of the high res there was no picture, audio wise there was no problem getting the Sony's groovy little blue light to come on and the whole 5.1 thing happening!

So what's the problem? The PC, the RME or the Sony? The Zensonic has no problem but not much joy direct from PC to date . . . ??. I've recently installed AC3Filter, set speakers out to SPDIF and all this seems to have done has made video playback really slow to start . . . !!??

Is it just a matter of finding the right (software) player?

Suggestions please?

[Sharktooth]

definatly wrong forum.

[poisson]

Really? Sorry . . . new at this . . . . where should I be posting this . . ??


Thanx.

[Sharktooth]

Audio forum or maybe Hardware players.
However just ask a mod to move the thread in the right place :)

[poisson]

Thanx for that. Will track down a mod.

Just curious . . . you suggested hardware players . . . how come. . . . I'm trying to get this happening from a PC . . ??

[Teegedeck]

*Moved to Audio Encoding*

[Sharktooth]

Thanx for that. Will track down a mod.

Just curious . . . you suggested hardware players . . . how come. . . . I'm trying to get this happening from a PC . . ??
oh... my bad, i wrongly understood even you HW player didnt recognize the 5.1 stream :)

[poisson]

Tried installing the ac3 filter. Switched speakers out to spdif. STILL no joy . . . . . ???

[kurt]

you could also try mpc (there is a new version around the forum): enable source filter for ac3/dts and the corresponding transform filter. Doubleclick on AC3 and enable spdif output...

[poisson]

MPC . . . ?? er . . . . Media Player Classic??

[kurt]

jep, media player classic i meant :)

[SeeMoreDigital]

The latest official version of MediaPlayer Classic can be found here ( http://sourceforge.net/project/showfiles.php?group_id=82303&package_id=84358&release_id=398635).

Just to let you know....

You don't have to have AC3Filter installed in order for you to send the raw AC3 (or DTS) stream along to your DSS amplifier, as MPC has it's own "internal" filters..

Personally speaking I would de-install AC3 filter while testing MPC

[poisson]

Hi Guys . . . . REALLY appreciate the input!!!
Here's what's been happening:
I followed Squid's suggestion of AC3 Filter and found no joy but left it installed.
AVIcodec gave me a more detailed analysis of the audio codec used in the "troublesome" clip in question . . . namely, "0x2000 = AC-3 ACM Decompressor".
I googled that and downloaded & installed AC3ACM v1.2 by fccHandler.
I then tried playing said clip with many of the 30 squillion players I have installed on my machine. Had no joy until I tried Windows Media Player v6.4.09.1130 and EUREKA!!! . . . 5.1 at last!!! I presumed it was the AC3ACM that did the trick.
But after a few 1000 celebratory cartwheels around the block I (hesitantly) decided I'd do some checking. 1st I uninstalled AC3ACM, rebooted and ran said WMP and the 5.1 still worked . . . !!
2CALSS, (To cut a long story short) I guess you can see what's coming . . . uninstalled AC3Filter . . . reinstalled . . . rebooted etc . . It appears that AC3Filter is the guy doing the honours but like I say, only with that player!!

So some questions are;
1.) Is the WMP mentioned here actually the MPC you guys are reffering to? If not then what is it?
2.) If it IS then is MPC 6.4.8.8 the latest version of it and will my beloved 5.1 still work?

3.) How come this player seems to be the only one to get the 5.1 thing going on or is there a way one can "point" other players in the "right" direction?

Thanx again guys, including Squid,

yours,

One Happy Chappy!!

[poisson]

mmmmmmm . . . . .just d/l MPC 6.4.8.8 . . . . I guess it AIN'T the same . . . . will check it out some . . . . or with MY (lack of) knowledge, should I quit while I'm ahead . . . . !!??

[kurt]

windows media player surely isn't the best solution (and it's not the same as mpc), but it seems to work for you. So be happy or try mpc as above-mentioned :)

[poisson]

Following your pointers Kurt and See More's de-install AC3Filter advice, I've just got MPC 6.4.8.8 and the 5.1 thang all happening! F'n great!! Cool looking program!!!

Thanx again guys!!!!

OH HAPPY DAAAAAAAAAAAAYYYYYYY!!!!!!!!!

[shpitz]

Audio = "448 Kbps, 48000 Hz, 2 channels"

just FYI, your audio is not 5.1, it's only 2.0 ac3.

[SeeMoreDigital]

Just to make sure your MPC settings are correct....

When playing your 6Ch AC3 files go to: -

http://img530.imageshack.us/img530/5633/ac3decoding5et.png


Cheers

[poisson]

Audio = "448 Kbps, 48000 Hz, 2 channels"

just FYI, your audio is not 5.1, it's only 2.0 ac3.

Really? Well . . . . . I've got my Sony amp (groovy little multi-channel-decoding blue light blazing away there!!) reading it as 3/2. There's sound in all six speakers (including sub). There's dialogue in the centre, background chatter in L & R front and music & atmospherics etc in the rear speakers and it all SOUNDS good. . . . . ????
Could it be just virtual 5.1 Shpitz? How can one readily tell the difference?
Or . . . . . with the whole xvid thing, can (genuine) 5.1 be embedded in those 2 trax (he asked, absolutely wincing at his own question!!)?


--------------------------------------------------------------------------------

[kurt]

you could open your videofile in Media Info (http://mediainfo.sourceforge.net/de) and see what audio information you get....

[poisson]

Here's Media Info's analysis of the file . . . .
File Name :xxxxxxxx.ac3.5.1.xvid-ctu.avi
File size : 698 MiB
Format : Audio Video Interleave
Overal BitRate : 2205 Kbps
PlayTime : 44mn 15s
Writing application : Nandub v1.0rc2

Video #0
Codec : XviD
Info : XviD project
Bit rate : 1747 Kbps
Width : 960
Height : 528
Aspect ratio : 16/9
Frame rate : 23.976 fps
(Pixel*Frame) : 0.144

Audio #0
Codec : AC3
Info : Dolby AC3
Bit rate : 448 Kbps
Channel(s) : 2 channels
Sampling rate : 48 KHz

Unless "Dolby AC3" automatically means 5.1, I don't see much evidence of 5.1. If so, where the h*ll's it coming from!!?? Is it some kind of virtual thing? If so, I wouldn't have thought the Sony would "see" it . . . . ??

[3dsnar]

Your home theatre (HT) amp should indicate what kind of stream
it is decoding.

However in case of 2 channel signal, it should be irrelevant
wether you are sending it as an AC3 or PCM, since
your HT equipment in first step produces PCM (if the input is AC3),
and than applies the DolbyProLogic decoding algorithm (which produces surround sound from the stereo input)

[tebasuna51]

There are two fields in ac3 header to define the number of channels: ACMOD (Values: 0..7) and LFEON (Values: 0/1).
Then is possible:
ACMOD front/rear channels LFEon LFEoff Description (Dolby ProLogic equivalent)
----- --------------------- ----- ------ ---------------------------------------
0 1+1 - Ch1, Ch2 - 1+1 Dual mono
1 1/0 - C - 1.0 Mono
2 2/0 - L, R - 2.0 Stereo (can be encoded DPL)
3 3/0 - L, C, R 3/0.1 3/0.0 Front-Center
4 2/1 - L, R, S 2/1.1 2/1.0 Old Surround
5 3/1 - L, C, R, S 3/1.1 3/1.0 Simple Surround (3/1.0 -> DPL I)
6 2/2 - L, R, SL, SR 2/2.1 2/2.0 Quadraphonic
7 3/2 - L, C, R, SL, SR 5.1 5.0 Standard Surround (5.0 -> DPL II)
At present the standards are 2.0 and 5.1 with typical bitrates:
2.0 -> 192 Kb/s
5.1 -> 448 Kb/s (also 384 Kb/s)

If your Media Info analysis is OK you have a stereo 2.0 with atypical bitrate 448 Kb/s.

EDIT:
Also there are another field in ac3 header to say if a 2.0 is Dolby ProLogic encoded: DSURMOD (Values: 0..3)
If this field is set to 2 (Dolby Surround encoded) your Decoder/Receiver can be set automatically in DPL decode mode sending output to all speakers.
If this field is set to another value than 2 you can force manually the DPL decode but the result is not guaranteed.

[shpitz]

Really? Well . . . . . I've got my Sony amp (groovy little multi-channel-decoding blue light blazing away there!!) reading it as 3/2. There's sound in all six speakers (including sub). There's dialogue in the centre, background chatter in L & R front and music & atmospherics etc in the rear speakers and it all SOUNDS good. . . . . ????
Could it be just virtual 5.1 Shpitz? How can one readily tell the difference?
Or . . . . . with the whole xvid thing, can (genuine) 5.1 be embedded in those 2 trax (he asked, absolutely wincing at his own question!!)?


--------------------------------------------------------------------------------


before you get 2 excited and start talking out of your ass, take a closer look @ the file analysis YOU SHOWED US, it says 2 channels (2.0) .

if your receiver says 3/2.1 either it's too retarded to know the difference, or the signal gets processed and converted to 5.1 before it reaches the receiver.

also your receiver has its own processing and it can output in several dsp forms, so what you hear from the speakers is not necessarily what the original audio was...

so get urself together, all i did was just point out what i saw from ur avi analysis... jesus

[shpitz]

OK . . . . hre's the Media Info analysis . . . . . Does "Dolby AC3" necessarily mean 5.1?

ac3 is an audio container, it can be 2.0, 5.1, w/e...

if u ever look @ autio menus on some of the dvd's you have, you'll find that some have DD5.1, DTS, and DD2.0 .

DD2.0 can be considered as just stereo in disguise, encoded into an AC3 stream. since AC3 has higher bitrate and uses DD technology it should be of a higher quality than a plain stereo mp3 stream...

[poisson]

Man . . . . What a learning curve!!! Thanx for all the info and apologies shpitz for any over excitement and/or lack of humility on my part.

While I'm trying to digest all this, would it be safe to put it all in a nut shell for the moment of; The "5.1" I'm hearing is DPL . . . . as in what was available in the 90s when there weren't DVDs, just VHS? But that perhaps the sound quality is up on what it was with VHS but not as good as today's genuine 5.1?

[shpitz]

hehe, glad you calmed-down...

obviously you can't compare VHS to anything today in terms of bandwidth and compression technology.

there are still DVDs and tv channels that broadcast DD2.0, personally i would prefer DD2.0 over stereo mp3, and with the receivers we have today they can do wonderful things with even just a stereo stream.

AC3 should be much richer than plain stereo mp3 but it all comes down to the quality of the encoder and there are many encoders out there. you can easily mess up a clip with bad audio and/or video encoding.

[poisson]

So the above file has 2 channel audio WITH imbedded DPL info. Is that correct? (I presume my HT amp is fed this info and just doesn't decide at random, "Jeez . . . I really LIKE this 2 channel audio I've been given at the moment. I think I might just chuck a bit of DPL II on this one!!"?) I don't know if either Gspot, Media Info etc actually tell you that (imbedded) info. Are there any programs that do?
How do you see the fields that Tebasana is talking about? Is the info there in the above Media Info analysis and I just ain't seeing it or do I need some other program?

[tebasuna51]

How do you see the fields that Tebasuna is talking about? Is the info there in the above Media Info analysis and I just ain't seeing it or do I need some other program?
Media Info analysis don't say if is Dolby Surround encoded and you need other program.

For this simple question you can use any hex editor (WinHex or equivalent) to open the ac3 file and look the 7th byte:
Offset | 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 |
-------------------------------------------------------------
00000000 | 0B 77 xx xx 1E 40 53 .. .. .. .. .. .. .. .. .. |
...
Where:
0B77 = Fix header start
xxxx = CRC 1 (variable)
1E = 00 011110 = 48 KHz, 448 Kb/s 896 words/frame
40 = 01000 000 = Standard, Complete main (CM)
53 = 010 10 011 = ACMOD, DSURMOD, others
Then if your 7th byte (offset 6) is between 50..57 you have a 2.0 Dolby Surround encoded.
Between 40..4F or 58..5F you have a 2.0 Not Dolby Surround encoded.
Others values for not 2.0 (and field DSURMOD not exist).

[Rockaria]

I got just overwhelmed by the equipments introduced...
<a decoding diagram in a graphedit view>

*.avi-> avi demuxer-> video decoder-> video renderer -> HDTV interface->Hitachi plasma screen
1. -> audio decoder(ac3filter/ffdshow/..)->(6ch upmix dsp)-> fireface 800 firewire sound device-> firewire(6ch pcm) -> fireface 800 -> spdif -> Sony STR-VA555ES
---------------------------------------------MP or MPC--------------------------------------------------------------
2. Normal route with PC sound system with spdif out -> ac3Filter/FFDShow dynamic ac3 encoding -> spdif(6ch ac3) -> (firewire 800) -> ""
3. "" + spdif passthrough ----------no decoding & umpixing(from 2ch)----------------------------------> spdif interface(?ch ac3) -> (firewire 800) -> ""

I guess you are taking the route 1., but still are not sure if it is decoding from(to) 2ch & upmixing(to 6ch) in the pc players.

File Name :xxxxxxxx.ac3.5.1.xvid-ctu.avi
Writing application : Nandub v1.0rc2
Frame rate : 23.976 fps
Codec : AC3
Bit rate : 448 Kbps

Normally, I believe Nandub v1.0rc2 + Gspot + MediaInfo + ac3 header info + human factor are not lying(mal-functioning).
But I agree there are something abnormal that do not concur the situation : the file name and the bitrate for 2ch use.
I believe even the DPL(II) does not require that much bit rate( just similar to the simple 2ch downmix, based on my tests)

In order to verify if the source is 2ch encoded, my idea is doing the following steps :
. check if the source volume matrix in ffdshow or ac3filter before upmixing has 6ch/2ch bars fluctuating
. demux to ac3 and perform : test play, fix(ac3Fix, besplit ac3 fix...), try opening it as 6ch-ac3-raw stream with applications like softEncode(ac3 encoder).
.....

Btw, because the DPL(II) containers are not limited to DD2.0(aac, ogg, wav/pcm, mp3...with no DPL meta info), the actual verification can be achieved mostly through DPL (II) decoding to 6ch(s/w, h/w).

[poisson]

Not sure how to upload images here but the link here is to a JPG of the 1st three lines of a Winhex analysis of the file in question. Can't (quite) figure out what to make of it. Can anybody help? Tebasuna?
http://img382.imageshack.us/my.php?image=winhexanalysis9xl.jpg

[poisson]

Your home theatre (HT) amp should indicate what kind of stream
it is decoding.


Just for clarification, my HT amp says it's streaming Dolby Digital 3/2. There's nothing in the display that says anything about DPL, I or II!!

[squid_80]

From that hex image it definitely appears to be 5.1 channels.

[tebasuna51]

The 7th byte is:
E5 = 111 00 10 1 = ACMOD, CMIXLEV, SURMIXLEV, LFEON

ACMOD = 7 = 3/2 - L, C, R, SL, SR
CMIXLEV = 0 = Center Mix Level -3 dB (recommended for downmix)
SURMIXLEV = 2 = Surround Mix Level None (recommended for downmix)
LFEON = 1 = Low frequency effects channel ON

Then you have an ac3 5.1 with typical bitrate 448 Kb/s and your Media Info analysis is wrong (6 channels).

Edit: The fields xMIXLEV is only a downmix recommendation for stereo output.

[poisson]

So is it OK I write Media Info and tell 'em their program sucks the big one!!!???? ; - )

[tebasuna51]

So is it OK I write Media Info and tell 'em their program sucks the big one!!!????
Yes, you can send them a bug report.:)

[poisson]

Well . . . . . to be fair, Media Info wasn't the only one. AutoGK seems to see it as "448Kbps AC3 2ch".

After rendering in Gspot, the audio path given is; "(S) --> AVI Splitter --> AC3Filter --> D&M MP2 Encoder(48KHz) --> CyberLink Audio Decoder --> (R)". Or before rendition, "ac3 (0x2000) Dolby Laboratories, Inc".

AVIcodec = " Audio : 141 MB, 448 Kbps, 48000 Hz, 2 channels, 0x2000 = AC3 DVM"

So it seems none of these guys is seeing it. I'm just curious as to what's going on . . . . ??

[SeeMoreDigital]

So it seems none of these guys is seeing it. I'm just curious as to what's going on . . . . ??You might just be unlucky... and have a 6Ch AC3 stream which has an incorrect (ie: 2Ch AC3) header.

What do you see when you download and play the following AC3_6Ch_'Speaker_Test' (http://81.98.148.105/51_Test_Encodes/AV_Setup_Tests/AC3_6Ch_'Speaker_Test'.7z) sample?


Cheers

[tebasuna51]

After rendering in Gspot, the audio path given is; "(S) --> AVI Splitter --> AC3Filter --> D&M MP2 Encoder(48KHz) --> CyberLink Audio Decoder --> (R)".
Really strange this mp2 encoder playing AC3. Maybe you have something wrong in your DirectShow configuration.
You only need an ac3 decoder like:
(S) --> AVI Splitter --> AC3Filter --> (R)
(S) --> AVI Splitter --> CyberLink Audio Decoder --> (R)
(S) --> AVI Splitter --> ffdshow Audio Decoder --> (R)
(S) --> AVI Splitter --> InterVideo Audio Decoder --> (R)
...
Or before rendition, "ac3 (0x2000) Dolby Laboratories, Inc".
The (0x2000) is the ac3 audio code, don't say nothing about
number of channels.
For ac3 5.1 GSpot say to me, below the Codec, a Info field with:
48000Hz 448 kb/s total (5 chnls)
Seems GSpot only check ACMOD and ignore LFEON.

I don't use Media Info, AutoGK or AVIcodec.
With VirtualDub in File -> File info -> Channels 6 (stereo?).
With AVIMux_GUI: AC3 (448 kbps CBR, 5 ch, 48KHz, ...)

[poisson]

What do you see when you download and play the following AC3_6Ch_'Speaker_Test' (http://81.98.148.105/51_Test_Encodes/AV_Setup_Tests/AC3_6Ch_'Speaker_Test'.7z) sample?


Cheers
Well as long as I'm using a player (MPC) that "sees" it, then my HT amp is saying "Dolby Digital 3/2". And yes, the (synthesized) voice is doing the correct thing . . . "right-front" etc.

[poisson]

Well that's the thing . . . . I'd like to clarify that there is or is not something wrong with my computer set-up before I'd write to Media Info etc. I wouldn't want them to come back at me with, "Aaaah Neddy . . . . you FOOL Neddy!!".