DVP642 "digital" audio problems ?

[absinthecarolinas]

Well my Philips DVP642 has served me so well that I went out a few months ago and bought a second one. The original was in my bedroom, hooked to a TV via the analog outs. The new one, however, I hooked up to my main TV and surround system downstairs with S-video and digital audio. "Fantastic," I thought, "now I can watch all my XviD encodes on the big TV downstairs!"

Off the top of my head I can't recall whether I used the optical or the coxial audio output, but regardless here's the issue:

With XviD/DivX files, the audio tends to fall behind, pop in and out, and lose sync during playback on the downstairs unit only. At first I thought it was only with AC3 files, but then I noticed that it happens with MP3 audio as well. The very same files on the very same disc will play back flawlessly on the upstairs unit. In fact, the DVP642 has always been an extremely tolerant player for me.

Indeed, the only difference I can think of is that the upstairs unit uses the analog outs (thereby downmixing multichannel to 2-channel stereo) whereas the newer, downstairs unit uses the digital audio out.

I suppose the ultimate test would be to simply switch the downstairs unit over to analog and see if the problem persists, but in the meantime I'm wondering if anyone else has experienced or heard of this issue. Perhaps there is a firmware fix?

Curiously, when the DVP642 (my "downstairs" one) is used to playback plain old DVDs, the digital audio seems to work fine.

-abs

[yoda313]

Hi,

Yeah try the other player first. Also check your submenus. There may be an option for maximizing divx surround sound for stereo systems - worth a look.

Also try switching between coaxial and fiber optic digital outputs to see if both have the same issue.

If worse comes to worse return the unit and ask for a replacement.

Kevin

[craiggus365]

I have 2 of these players. I play divx & xvid frequently (w/ the same hook-up you are using) and have never experienced this. I can't imagine anything else but a defective unit.

[hexxisoft]

yeah, same here. yours might be defective.

(haha, nice location... too close to Newark NJ, i work there.)

[Junpei]

I have audio sync and cut out issues fairly frequently with Xvid files with AC3 audio. No problems with MP3 audio though (well... I haven't played one with MP3 audio in a while, so I can't be positive).

I just attributed it to the player being pickier about these files, I don't know the reasons. I haven't tried using analogue stereo output but I'm quite certain it's a problem with the digital audio only. I'm using a digital coaxial cable. No problems with any DVDs.

Are these DVP642/37's that you have? What's the firmware version on each? Is the problematic one a newer model?

[obsolete]

I use the coaxial digital out on my Philips DVP642 and I don't have any dropouts or other problems on Divx/Xvid's with ac3 or MP3, or any other formats.
Don't forget to consider whether or not your surround system is the problem...

[absinthecarolinas]

Yes, my model is a DVP642/37. The one I'm having the trouble with was manufactured in March 2005, and it's "newer" to me, which is to say I bought it more recently. I haven't checked the dates on the one I've had longer, but I probably had that one for 3 to 6 months before I bought the second one.

I looked at the firmware version last night on the problem unit, but I can't recall it exactly off the top of my head. I think it was 1109. Anyway, I was planning on trying to flash it with 0112 today.

Interestingly, I did switch the audio on the problem unit over to the analog outputs, and now everything plays perfectly. So go figure. That to me almost doesn't make sense. I mean, with analog, it seems like the player has to do even more work. It has to downconvert to 2 channels internally before passing along the audio. In terms of digital, it simply passes along the stream. Using the analog outs, the player is still reading the stream right out of the AVI file and is doing so perfectly ... otherwise the sound wouldn't be correct! So if it can read the stream out of the AVI file, why can't it pass it along correctly? And I don't think it's my receiver setup; it plays all multichannel DVDs just fine and has done so for several years.

Anyway, today I want to bring my upstairs unit down and see if I can duplicate the problem with the digital audio. If I can't, then I'm going to try a firmware upgrade. I've probably owned both units more than 90 days so I don't know what options I'd have in terms of a replacement.

As far as the possibility of the problem being related to the files themselves, I think I can rule that out. I've made hundreds if not thousands of XviD files and I check all aspects meticulously. I definitely know what I'm doing in that regard.

(It just occurred to me that I have a newly purchased 5.1 receiver in another room upstairs. It only has 3 speakers hooked up to it, but that would be enough to hear if audio stays in sync. I might try hooking one or more players up there and see if can duplicate the problem that way, too).

-abs

[Junpei]

I got my player last November and it has, I believe, firmware version 0531. I have yet to update it.

Considering I've also had problems with the audio and I have (probably) very different audio hardware, it seems more likely a DVP issue. Granted my Logitech speakers with built-in receiver are not really high-end equipment, but I've never had ANY problems with them on ANY other hardware or ANY other media through the DVP. It's only Xvid (I don't know about Divx, I wish I had more files to test) encoded AVIs with AC3 audio. And hell, not all of them either—I know at least some files that play perfectly. But most don't.

It seems to more more like a problem the DVP is having passing the digital stream over to the audio hardware. But I can't claim I know what I'm talking about.

I'll be interested to know how your tests turn out.

P.S. I'll also add that the files play perfectly on my computer, where they are being compressed to analogue stereo output (I wish I had digital output so I could see if there was an audio problem using the computer).

[KiwiKid]

I have just bought a second 642 for another room and noticed audio problems. Audio seems to cut out very briefly at various times. You really notice it when there is background music and it cuts out as the scene or camera angle changes. My 642 is only hooked up to the TV - no receiver etc. I watched an avi two nights ago with many dropouts but the next night watching another avi I didn't notice any. I have lent the problematic avi to a friend so I can't compare the audio specs yet. I'll keep you posted if I learn anything.

[absinthecarolinas]

OK, Problem Solved

After trying every possible permutation of hookup between two DVP642/37 units and two 5.1 receivers, I decided to take another look at my files.

Now, when it comes to muxing MP3 into AVI, I've always just left the muxing settings in VirtualDubMod at their defaults (500 ms preload, 1 frame interleave). All files I'm testing seem to work fine via the digital outs. Perhaps I was mistaken earlier when I said I had noticed an MP3 soundtrack playing with skips/desync'ing via digital outs; I've looked at so many darned files lately, it's possible.

Anyway, when it comes to AC3 I have read time and again very specifically to use a preload and interleave of 96 ms, or some say 64 ms. I don't know why, but apparently there's something about AC3 and multiples of 32. I have always muxed my files this way and have never had a problem.

That is, until I started trying to play them through digital audio outs to a 5.1 channel decoder.

On a lark, I demuxed a file and then re-muxed the AC3 back in with VirtualDubMod's default settings: 500 ms preload, 1 frame interleave, i.e. the same settings used for MP3).

I am happy to report that files muxed this way play back absolutely flawlessly through digital outs. I don't know where this wisdom about 64/96 ms interleaving/preloading comes from, but it sure doesn't work with the Philips DVP-6xx models.

I've tried several variations, including 96 ms preload with 1 frame interleave. That didn't work either.

I've also tried AVIMuxGui. Funny thing with that is, even though the default seems to be 500 ms/1 fr., GSpot will report the file as being interleaved every 1.5 frames. In order to force 1 frame interleaving, I had to go to "page 2" of the AVI structure settings and change the "AC3 frames per chunk" setting from its default of 2 to a setting of 1. The number 1, however, shows up in red when you do this, as if it's some kind of warning. However, the file produced does indeed finally show in GSpot as interleaved every 1 frame. Still, I get the skipping and desyncing on playback.

I'm sure there's some way to use AVIMux to produce playable files. Perhaps I'll inquire at doom9; I believe the author frequents the forum there.

Anyway, for now, the bottom line seems to be: If you want to produce AVI files with AC3 playable via digital outs on the Philips DVP-642 and related models, try muxing with VirtualDubMod using its default settings (500 ms preload; 1 frame interleave).

I hope this helps others. It's been a struggle for me

-abs

[Junpei]

Edit: deleted.

[Junpei]

Could you explain how to demux/mux a problematic AVI, then? I'm lost and there's no information on how to do this with VirtualDubMod.

[absinthecarolinas]

Sure thing

Actually, no demuxing should be necessary. All you have to do is open the file in VDubMod and resave. In fact, I think it would be preferable not to demux. I'll explain.

Because the settings that work are VDubMod's default settings, you don't have to actually change a darn thing. You simply open your video file with VDubMod. Now, just to be sure you can go Streams > Stream List. You should then see your audio stream in a gray box. Right click on it and click "interleaving." The box that comes up should say that preload is set to 500 ms, and interleave on every 1 frame. Audio delay should be set to 0, and you should leave it that way if your file is already in sync. Click Ok. Now, just to be sure, right click once again on the gray box and make sure that "Direct Stream Copy" is checked for your audio stream. It should be by default. Click ok to return to the main VDubMod screen.

Under Video, select "Direct Stream Copy."

Then simply go File > Save As and save your file. That's it. The new file will be now be properly indexed (should solve those pesky FF and RW issues) and should play back AC3 properly through digital outs on the Philips players.

Now in truth, you don't have to check all those settings because they are defaults. I only tell you in case something goes wrong so you'll know how to check. In other words, it's just as simple as:

1. Open your file in VDubMod.
2. Check "Direct Stream Copy" under the video menu.
3. File > Save As, and save your file.

In fact, there's even an option to select "direct stream copy" in VDubMod's "Save As" menu, so you could even skip step #2 if you like and select direct stream copy from the "save as" page.

The reason I said it would be better not to separately demux and then remux is that if there is a delay in the audio stream as it is currently muxed, you will lose that delay if you demux and your file will be out of sync. I've often wondered if simply opening a file in VDubMod and resaving this way would preserve audio delay settings, and with my testing in the last couple of days I can assure you that it will.

Now on the topic of audio delay, I've also learned the hard way that the Philips player doesn't like long audio delays. I once had a file that would not play no matter what but that I knew for certain was perfectly fine. I struggled with that for some time before I realized that the studio logo at the beginning of the movie was silent. Examining the file, there was a monstrously long audio delay. Basically, the whole 15-or-20-second-long studio logo had no audio behind it. I demuxed the audio, corrected the delay with AC3 Delay Corrector (which added silent AC3 in place of nothingness), and remuxed. Voila! File worked fine.

Now usually audio delay is only a few to a coupla hundred ms. If I had to guess, I would say not to use a delay of greater than 1000 ms (1 second). If you come across an audio file with a delay of 1000 ms or greater, I think I would correct it with AC Delay Corrector before muxing.

Anyway, back to the topic at hand ... now, examine your new file with GSpot. Look under the "container" header. If it is properly muxed it should say something like "interleaved every 1 frame (42 ms), preload 512 ms." That's what it says when I mux correctly with VDubMod.

And that's all she wrote.

-abs

[Junpei]

That fixed it perfectly on the file I tested. Awesome! That's quite simple to do too.

In GSpot I don't see a "container" header (diff version maybe?), but it does say "1 vid frame (42 ms) Split: No

[absinthecarolinas]

That's great to hear. Glad it worked!

Yes, I use the latest Gspot. You can check for the newest version here at vhelp.

-abs

[KiwiKid]

I got the problematic AVI back from my friend and followed the simple instructions. Worked for me too. Thanks