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mvallevand
2007-03-14, 01:38 AM
In tonight's (0313) dongle, I thought I'd have some fun and so I enabled AC3 audio. It is only for fun because the audio and video are terribly out of sync but I thought someone might be interested in see what the mvpmc is capable of.

I actually only tested with VOB files in mvpmc native mode but it could work with emulation mode if the following conditions are valid

1. You have digital output on one of the newer revision H mvp's or you have mod'ed your older mvp, perhaps using jksmurf's execellent guide at this link

http://www.mvpmc.org/~stuart/HAUPPAGE_MEDIAMVP_TOSLINK_Installation_Summary.pdf

2. the only audio stream in the file is AC3

3. GBPVR sends the mpeg file without transcoding

4. AC3 passthru is enabled via the Settings menu option or through the command line option -o passthru

I'd be curious getting feedback on this.

Martin

mvallevand
2007-03-29, 04:21 AM
I forgot to mention that starting in the last alpha (0327) I have provided a way to manually sync the AC3 a/v when using either the pure AC3 pass through feed or the AC3 downmix to stereo on your tv or via the analog output. The keys are

* slow video by 1/100 of a second
# slow video by 1/1000 of a second

Note that I could set an option to downmix AC3 on analog to Dolby stereo instead of stereo, if anyone wants to try this.

Martin

jksmurf
2007-05-16, 03:42 AM
I'm disappointed that no one cares about AC3, MartinI don't think no one cares but:

Personally, I really don't know much about AC3 (http://ac3filter.net/guides/how_to_playback_multi_channel_ac3_dts_audiocd). I'd hazard a guess a lot of other folks think the same. If you don't have DVB yet (like me) you won't be using it right?
I guess it only makes sense if you have a NEW MVP with SPDIF, so that cuts out an awful lot of users for a start?
I have read quite a few posts that it works but is "out-of-sync". So how can I test it for you? With a DVD?
Presumably I have to install an AC3 filter? Is there a recommended one? AC3Filter (http://downloads.sourceforge.net/ac3filter/ac3filter_1_30b.exe), DScaler, FFDShow? I understand that PowerDVD 7 (http://forums.nextpvr.com/showthread.php?t=25134&highlight=spdif+cyberlink) does NOT have SPDIF output. I have (and use) Nvidia PureVideo Decoder which I understand has (http://forums.gbpvr.com/showpost.php?p=179886&postcount=7) 5.1 but I get a problem with "Audio Decoder: NVIDIA Audio Decoder" as documented here (http://forums.nextpvr.com/showthread.php?t=26265).
Do you have to have a "grunty" PC for AC3, maybe not for AC3 itself, but the accompanying Video Codec / on the fly transcoding? If so, then maybe my PC is too pathetic to do this :o
Is this an issue? "But it is a big problem with SPDIF passthrough mode: most sound cards cannot work with 44100Hz SPDIF sample rate (used by AudioCD). Currently it is no workaround for this. The only solution possible is to resample audio from 44100Hz to 48000Hz. But this feature currently is only in plans."Sorry for soooo many Q's!!

k.

mvallevand
2007-05-16, 04:48 AM
I don't think no one cares but:
Do you have to have a "grunty" PC for AC3, maybe not for AC3 itself, but the accompanying Video Codec / on the fly transcoding? If so, then maybe my PC is

I've moved the post here because I want to try to keep everything together. For AC3 all the work is done by mvpmc so your server really isn't impacted other then the audio portion of the file is bigger and it pushes the server and the network a bit more, although nothing close to the size of the video though. Definitely no AC3 filter, or on the fly transcoding, or even sound card on the gbpvr server is necessary.

I guess the easiest way for you to test is with a VOB renamed to MPG. Note my second post for the keys to manually sync the a/v. I think will be able to sync these better but I'm going to need some DVB and ATSC samples.

Also this works for any emulation mode user. If passthru isn't available the AC3 is downmixed to stereo and as mentioned I could downmix to surround sound if that was prefered (or I could even add another command line option :) )

Martin

jksmurf
2007-05-17, 09:05 AM
For AC3 all the work is done by mvpmc so your server really isn't impacted other then the audio portion of the file is bigger and it pushes the server and the network a bit more, although nothing close to the size of the video though. Good news.

Definitely no AC3 filter, or on the fly transcoding, or even sound card on the gbpvr server is necessary.Better news.

I guess the easiest way for you to test is with a VOB renamed to MPG. Note my second post for the keys to manually sync the a/v. I'll try it tonight hopefully.
Q1. Is it still only the (0313) dongle?
Q2. My MVP is downstairs, my PC upstairs. My guess is MVP owners keep these seperate, otherwise they probably wouldn't have an MVP :-). My point is, that you'll have me running up and down the stairs to press the * and # keys ... so would a future test dongle be able to programme the remote keys instead e.g. Channel Up down or sth else? to make this test adjustment?
Q3. Is Video always faster than AC3 (you have no speed up video key...in case I go too far....)

I think will be able to sync these better but I'm going to need some DVB and ATSC samples. Where can I get a DVB stream to test? There must be 100's folks here with a short clip :-) How about a donation ...

k.

HtV
2007-05-17, 09:31 AM
My point is, that you'll have me running up and down the stairs to press the * and # keys ...


It's nice picture: Mrs on the sofa, JK running up and down the stairs......:D You might skip the gym, might even save you some money, better not let mrs know.:eek:

mvallevand
2007-05-17, 04:42 PM
Good news.
Better news.
I'll try it tonight hopefully.
Q1. Is it still only the (0313) dongle?
Q2. My MVP is downstairs, my PC upstairs. My guess is MVP owners keep these seperate, otherwise they probably wouldn't have an MVP :-). My point is, that you'll have me running up and down the stairs to press the * and # keys ... so would a future test dongle be able to programme the remote keys instead e.g. Channel Up down or sth else? to make this test adjustment?
Q3. Is Video always faster than AC3 (you have no speed up video key...in case I go too far....)


A1 - All since then, plus last night I built 0511 to mvpmc so it's all in the nightly now

A2 Funny, the keys are on the new remote. I haven't figured out how to do this logically on the old remotes.

A3. No but I've never seen it start the other way around however if you keep slowing down the video it will be slower than the audio.

Martin

pz1
2007-05-18, 07:58 AM
A1 - All since then, plus last night I built 0511 to mvpmc so it's all in the nightly now

Martin,
What do you prefer us to test, the alpha or the nightly?
Pieter

mvallevand
2007-05-18, 04:44 PM
Martin,
What do you prefer us to test, the alpha or the nightly?
Pieter

Right now there better be no difference. The nightly will be more static (not necessarily better) with 99.12 the alpha will no address future versions where I might have to get experimental again. I will keep the changelog.txt current.

Martin

zehd
2007-05-18, 08:53 PM
3. GBPVR sends the mpeg file without transcoding



Martin,

You know, I haven't really played much with this, but it might be time. Would you say that you don't want on- the- fly transcoding, because the transcoder may drop the multichannel sound, or downmix it?

From my perspective I would want to see ZProcess work with mvpmc, but haven't really tried yet. I have built 6 channel sound into ZProcess but haven't been able to use it yet because of the MVP being 2 channel only , til now...

I'll check through your sub-forum a bit more and see...

mvallevand
2007-05-18, 10:02 PM
You know, I haven't really played much with this, but it might be time. Would you say that you don't want on- the- fly transcoding, because the transcoder may drop the multichannel sound, or downmix it?
There are two reasons, with AC3 passthru it is pretty clear why, for the internally downmixed audio I don't want to lose valid time stamp information.


From my perspective I would want to see ZProcess work with mvpmc, but haven't really tried yet. I have built 6 channel sound into ZProcess but haven't been able to use it yet because of the MVP being 2 channel only , til now...
For digiital out only. It might be a good marriage with all the xvid/ac3 mp4/ac3 and HD/ac3 files. ZProcess might even insert key frames to help me correct the current a/v sync issues.

Martin

JimF
2007-05-18, 11:19 PM
Are you aiming to get it to work with analog output too, or is that not possible?

mvallevand
2007-05-18, 11:45 PM
Are you aiming to get it to work with analog output too, or is that not possible?

Right now mvmpc does downmix to stereo on the analog output, but it could be made configurable to downmix to surround instead.

For the technically inclined mvpmc use the liba52 modules to do this. I have no idea how will the surround sound downmix sounds.

Martin

jksmurf
2007-05-19, 01:29 AM
A2 Funny, the keys are on the new remote. I haven't figured out how to do this logically on the old remotes.Oops, I never even noticed those buttons before....I HAVE the new remote :o

OK, I finally got around to trying the Movie.VOB renamed to Movie.MPG (after testing it on the PC first to make sure it ran OK there before subjecting it to the MVP. I had problems with this testing it on the PC initially, as TBH I have never played videos via GBPVR on the PC.*

In any case the Video played perfectly as expected (MPEG2) but the audio was not only widely out of sync, it was extremely choppy (via a wired MVP over a wireless WRT54GS-WRT54GS Bridge).

Don't take this as a critisicm, I know you're really pushing the boundaries here, but while it is interesing to see that it is certainly "capable" of AC3, and if the choppiness was overcome, it could possibly be used by a 5.1 afficionado keen to mash # and * a few times. (btw once synced does it STAY that way, suffice to say I didn't watch the entire movie, it was already 1:30 a.m. by the time I got that far ... ).

I really had a good go at those # and *keys.

Now, I haven't got around to sticking in the Test Dongle to get logs, but (a) Does that Test Dongle have AC3 enabled and
(b) Do you need logs or just a general comment?

* As an aside I must categorically state that Nvidia's integration of their own Audio Codec with their quite good Video Codec leaves much to be desired, at least in GBPVR, despite claiming that it can do AC3. It would play Video, but no sound. I have documented this in another (existing thread (http://forums.gbpvr.com/showpost.php?p=197328&postcount=10)).

Cheers

k.

mvallevand
2007-05-19, 01:52 AM
In any case the Video played perfectly as expected (MPEG2) but the audio was not only widely out of sync, it was extremely choppy (via a wired MVP over a wireless WRT54GS-WRT54GS Bridge).


Thanks for doing the test. Playing a vob does take a lot of bandwidth, it might be interesting for you to try an mvpmc throughput test to see what your system is capable of. If you are interested

1 place a vob or mpg in your mvpmc folder on your gbpvr server
2. instead of going into emulation go to filesystem on your mvp
3. browse to /etc/mvpmc
4. cursor to your file
5 hit the menu button and select throughput test
6. let hit play for thirty seconds
7. hit stop and record your rate

I get about 10Mbs, some mvpmc users have hit 13,

You might be interested in seeing how mvpmc native handles it too, just hit select to play it.




Don't take this as a critisicm, I know you're really pushing the boundaries here, but while it is interesing to see that it is certainly "capable" of AC3, and if the choppiness was overcome, it could possibly be used by a 5.1 afficionado keen to mash # and * a few times. (btw once synced does it STAY that way, suffice to say I didn't watch the entire movie, it was already 1:30 a.m. by the time I got that far ... ).


I don't consider it criticism. In fact the reason I called this fun is I want to see how many people can hear the audio ok before I spend time trying to sync automatically.



I really had a good go at those # and *keys.

I only use the pound/hash/octothorpe/number ? key. The asterisk is too fine.



Now, I haven't got around to sticking in the Test Dongle to get logs, but (a) Does that Test Dongle have AC3 enabled and
(b) Do you need logs or just a general comment?

a yes the mvpmc debug dongle has ac3 and the same emulation code
b comments are fine, but the throughput test would be more valuable then the logs.

Thanks again,

Martin

jksmurf
2007-05-19, 05:59 AM
but the throughput test would be more valuable then the logs. Martin

6.34 mb/s. :-( I ran it for a minute...

Disappointed!!!

I have all Tipstirs network tweaks installed, maybe I need to look at Router Tweaks as it runs through 2 of those before it gets to the NIC in my PC.
WDS Mode is only 1/2 duplex I understand ...

Disappointed!!!

k.

HtV
2007-05-19, 08:40 AM
It's quite a miracle the movie itself played ok, must have been not too high bitrate.
I don't know what distance there is between router and mvp, I do know that throughput can go down very quickly with increasing distance.

I guess it's time to get the drill out and roll out some cat-cable.:D

Hans

mvallevand
2007-05-19, 12:06 PM
6.34 mb/s. :-( I ran it for a minute...

Disappointed!!!

I have all Tipstirs network tweaks installed, maybe I need to look at Router Tweaks as it runs through 2 of those before it gets to the NIC in my PC.
WDS Mode is only 1/2 duplex I understand ...

Disappointed!!!

k.

That's not a terrible bit rate but could be low for vob's. Tweaks that work for one network don't always work for another. The 1/2 duplex is more of a concern to emulation which this thruput test but it could have an impact. Again I'd be curious how it plays in mvpmc native mode.

Martin

jksmurf
2007-05-20, 02:55 PM
Again I'd be curious how it plays in mvpmc native mode. Martin

1. What IS mvpmc native mode?
2. I tried Server PC <=>WRT54GS (AP) <=Wireless=> WRT54GS (Wireless Ethernet Bridge) <=> MediaMVP to get past WDS mode 1/2 duplex restriction, but I get 5.17mb/s, even less :confused: !!

k.

mvallevand
2007-05-20, 03:14 PM
1. What IS mvpmc native mode?

I meant playing the file without using emulation mode. Instead of doing the throughput test just hit the OK button to play the file.


2. I tried Server PC <=>WRT54GS (AP) <=Wireless=> WRT54GS (Wireless Ethernet Bridge) <=> MediaMVP to get past WDS mode 1/2 duplex restriction, but I get 5.17mb/s, even less :confused: !!

I think with wireless network performance is difficult to quantify, and here you are adding in the complexities of the share if the server or drive is busy etc and also a test of the mvpmc demux speed with a specific mpeg file.

If you want to test the network and disk speed without testing mvpmc performance this command from telnet will do that.

time dd if=/etc/mvpmc/your.mpg of=/dev/null bs=8192 count=512

count is the number of 8k block you want to read, this is a 4 MB test. As an example from various shares I have

Vista (fast SATA) 2.10s
Maxtor MSS+ 2.18s
NSLU2 (slow PATA) 2.59s

BTW I can duplicate an error -195 on a windows share but I don't get the 0 byte file. I was testing this via my NSLU2 and obviously Samba and Windows aren't quite the same. The solution was just that the guest account didn't have the write access authorization.

Martin

jksmurf
2007-05-21, 01:21 AM
BTW I can duplicate an error -195 on a windows share but I don't get the 0 byte file. I was testing this via my NSLU2 and obviously Samba and Windows aren't quite the same. The solution was just that the guest account didn't have the write access authorization. Martin

Thanks Martin, I'll try the newtork test when I get home, but regarding the write permissions, I've had a Bobin's moment :p (no disrepect to Bobin's). I guess the share does not have WRITE access, as "Simple File Sharing" defaults to only read access?

Correct me if I'm wrong, but I guess I was confused by a previous post (http://forums.gbpvr.com/showpost.php?p=196658&postcount=52) and subsequent discussions into thinking I "should" have "Simple File Sharing" enabled? At work with XP Pro this is not enabled and I can change the share permissions, which I do quite often. With "Simple File Sharing" disabled (Explorer, Tools, Folder Options, View) I can add "full control to the dir", rather than just read, which I believe will now work ...

2 Q's

1. If I do this and then re-enable "Simple File Sharing" will it still work (I guess I could try that out).

2. I have XP Pro, but this site (http://www.practicallynetworked.com/sharing/xp_filesharing/index.htm) says "Simple File Sharing is the only type of sharing available in Windows XP Home Edition". If this is indeed true, how do those with Windows XP Home change write permissions on shares?

k.

mvallevand
2007-05-21, 02:20 AM
Thanks Martin, I'll try the newtork test when I get home, but regarding the write permissions, I've had a Bobin's moment :p (no disrepect to Bobin's). I guess the share does not have WRITE access, as "Simple File Sharing" defaults to only read access?

Corretc me if I'm wrong, but I guess I was confused by a previous post (http://forums.gbpvr.com/showpost.php?p=196658&postcount=52) and subequent disucssions into thinking I "should" have "Simple File Sharing" enabled? At work with XP Pro this is not enabled and I can change the share permissions, which I do quite often. With "Simple File Sharing" disabled (Explorer, Tools, Folder Options, View) I can add "full control to the dir", ratehr than just read, which I believe will now work ....

You can do it without Simple File Sharing on. I was just trying to get people with problems back to Windows defaults so that we are all talking from the same reference point. Then the tweaking can begin again, this time not worrying as much about the guest account.

.

1. If I do this and then re-enable "Simple File Sharing" will it still work (I guess I could try that out).
.
If you haven't removed a necessary component through a tweak yes.



2. I have XP Pro, but this site (http://www.practicallynetworked.com/sharing/xp_filesharing/index.htm) says "Simple File Sharing is the only type of sharing available in Windows XP Home Edition". If this is indeed true, how do those with Windows XP Home change write permissions on shares?
.
Thats one of the reasons for suggesting shrpubw on the wiki, it makes setting permissions easy. You can do a lot with CACLS too, I'm hoping that we don't have to resort to using it.

Martin

mvallevand
2007-05-23, 11:41 AM
I guess the easiest way for you to test is with a VOB renamed to MPG. Note my second post for the keys to manually sync the a/v. I think will be able to sync these better but I'm going to need some DVB and ATSC samples.

My new HVR 1600 does store AC3 with the QAM stereo broadcasts in DVD format so this isn't a problem anymore. On the mvpmc forums I did get a short mpeg transport stream file and I confirmed that mvpmc doesn't decode mpeg-ts AC3 audio yet. Now what I need is a couple of 30-50MB mpeg-ts files.

Martin