absinthe
7th August 2005, 19:49
I've got a topic on which I need to get down to the nitty gritty details if anyone out there can shed some insight. Namely, how to properly mux AC3 into an AVI. No, I mean reaaaaaally properly. More specifically, how to do it so that it will play back properly via the digital audio output from a Philips DVP642 (and I assume other related Philips players, maybe all Mp4 standalones).
I've seen numerous threads come and go about sync issues with AC3 in the DVP642. I had always assumed I was lucky because my files always played fine. I figured I knew what I was doing.
Here's the thing. I now own 2 of these handy, dandy players, the newer of which I hooked up to my main TV and receiver downstairs, which is a 5.1 channel receiver, via the optical audio output. My older unit had always been hooked up to my bedroom TV via the analog outs.
Now, the player doesn't seem to finicky about how audio and video is muxed when sound is played through the analog outputs. I had never experienced a single problem with my older unit. But when I hooked it up via a digital out, whether optical or coaxial, suddenly every file with AC3 would stutter, skip, and lose sync.
I struggled with this for days. I tried everything with the player itself short of a firmware upgrade, which I was really hesitant to do. I hooked up both players to both TVs, and also to a second 5.1 receiver I had, and the problem always persisted. But, plug the unit up via analog outputs and whammo, perfect playback again on the exact same files on the exact same discs.
So I took another look at my files. Now I have been told in the past to always mux in AC3 with a preload and interleave of 96 ms (some say 64 ms). Apparently there's something magical about AC3 audio and multiples of 32, so that's what I've always done. Near the end of my rope with frustration with this recent digital audio issue, on a lark I remuxed a file back together through VDubMod at default settings (that is, 500 ms preload, 1 frame interleave).
And like magic, all audio problems disappeared.
So there you have it, using 500 ms preload and 1 frame (not 1 ms), the same settings I had always used for MP3 audio in AVI, will render AC3/AVI files that should play back perfectly through the digital outs of the Philips DivX standalones. No wonder it's the default, eh? :p At least it's worked with every file I've tried so far. (I should note that other combos do not work: i.e., 96 ms/1 fr, 64 ms/1 fr, etc.)
I'm hoping this will help someone out there, but at the same time I'd like to ask, if anyone knows: Where does this wisdom about muxing AC3 in 32/64/96 ms intervals come from? I have read/heard this from several different sources, so there must be something to it.
Speaking of VDubMod, I also tried to mux with AviMuxGui. Now, even though 500 ms/1 frame is the default for muxing in that application, the files still experienced the skipping and desync'ing. And yes, I did disable the use of OpenDML. (In fact, if you try to play an OpenDML AVI in my Philips standalone, it freezes the unit altogether. The power button won't even work).
Anyway, files produced by AviMuxGui at 500 ms/1 fr show up in GSpot as actually having an interleave of 1.5 frames. I played with this a while and found that by changing the "AC3 frames per chunk" setting (on page 2 of the AVI file structure tab) from its default of 2 to 1, I could produce a file that showed up in Gspot as actually having a 1-frame interleave. However, when you change that setting in AviMuxGui, the number 1 appears in red, as if some kind of a warning. Also, the file produced (the one with 1-frame interleave) still will not play properly.
I guess I'm wondering if someone knows how AviMuxGui can be used to duplicate VDubMod's default muxing settings.
And on a final note, something else that's always confused me is this whole OpenDML issue. Now, the Philips model (and others as well, I think) apparently doesn't support OpenDML AVI files. However, all files output by VDubMod at default settings show up in GSpot as being OpenDML files. It was once explained to me long ago by a member here at doom9 (I believe it was stephanV) that files output by VDubMod aren't really OpenDML; there's just some junk header in there that says they are. Now, if that's true, and I have no reason to doubt it, then what the heck are they?
Sorry to be so long-winded. But I was about 3/4ths of the way through backing up my entire DVD collection to XviD when I discovered this problem. Now I'm going to have to remux, reburn, and trash about 30 DVDs full of movies :)
-abs
I've seen numerous threads come and go about sync issues with AC3 in the DVP642. I had always assumed I was lucky because my files always played fine. I figured I knew what I was doing.
Here's the thing. I now own 2 of these handy, dandy players, the newer of which I hooked up to my main TV and receiver downstairs, which is a 5.1 channel receiver, via the optical audio output. My older unit had always been hooked up to my bedroom TV via the analog outs.
Now, the player doesn't seem to finicky about how audio and video is muxed when sound is played through the analog outputs. I had never experienced a single problem with my older unit. But when I hooked it up via a digital out, whether optical or coaxial, suddenly every file with AC3 would stutter, skip, and lose sync.
I struggled with this for days. I tried everything with the player itself short of a firmware upgrade, which I was really hesitant to do. I hooked up both players to both TVs, and also to a second 5.1 receiver I had, and the problem always persisted. But, plug the unit up via analog outputs and whammo, perfect playback again on the exact same files on the exact same discs.
So I took another look at my files. Now I have been told in the past to always mux in AC3 with a preload and interleave of 96 ms (some say 64 ms). Apparently there's something magical about AC3 audio and multiples of 32, so that's what I've always done. Near the end of my rope with frustration with this recent digital audio issue, on a lark I remuxed a file back together through VDubMod at default settings (that is, 500 ms preload, 1 frame interleave).
And like magic, all audio problems disappeared.
So there you have it, using 500 ms preload and 1 frame (not 1 ms), the same settings I had always used for MP3 audio in AVI, will render AC3/AVI files that should play back perfectly through the digital outs of the Philips DivX standalones. No wonder it's the default, eh? :p At least it's worked with every file I've tried so far. (I should note that other combos do not work: i.e., 96 ms/1 fr, 64 ms/1 fr, etc.)
I'm hoping this will help someone out there, but at the same time I'd like to ask, if anyone knows: Where does this wisdom about muxing AC3 in 32/64/96 ms intervals come from? I have read/heard this from several different sources, so there must be something to it.
Speaking of VDubMod, I also tried to mux with AviMuxGui. Now, even though 500 ms/1 frame is the default for muxing in that application, the files still experienced the skipping and desync'ing. And yes, I did disable the use of OpenDML. (In fact, if you try to play an OpenDML AVI in my Philips standalone, it freezes the unit altogether. The power button won't even work).
Anyway, files produced by AviMuxGui at 500 ms/1 fr show up in GSpot as actually having an interleave of 1.5 frames. I played with this a while and found that by changing the "AC3 frames per chunk" setting (on page 2 of the AVI file structure tab) from its default of 2 to 1, I could produce a file that showed up in Gspot as actually having a 1-frame interleave. However, when you change that setting in AviMuxGui, the number 1 appears in red, as if some kind of a warning. Also, the file produced (the one with 1-frame interleave) still will not play properly.
I guess I'm wondering if someone knows how AviMuxGui can be used to duplicate VDubMod's default muxing settings.
And on a final note, something else that's always confused me is this whole OpenDML issue. Now, the Philips model (and others as well, I think) apparently doesn't support OpenDML AVI files. However, all files output by VDubMod at default settings show up in GSpot as being OpenDML files. It was once explained to me long ago by a member here at doom9 (I believe it was stephanV) that files output by VDubMod aren't really OpenDML; there's just some junk header in there that says they are. Now, if that's true, and I have no reason to doubt it, then what the heck are they?
Sorry to be so long-winded. But I was about 3/4ths of the way through backing up my entire DVD collection to XviD when I discovered this problem. Now I'm going to have to remux, reburn, and trash about 30 DVDs full of movies :)
-abs