No audio unless played at 1.5X speed

[hf]

Hi, Not really sure which forum to post this to,
but I though I'd try here to see if anyone has any
ideas.

I'm trying to backup a disk that was apparently created
from a VHS tape. The problem I am having is that when
I play the ORIGINAL in my standalone JVC player, I only
get sound if I play it at 1.5X speed. At normal speed
there is no sound. I used the latest dvddecryptor to
dump it on my pc. If I try to open it with DVDshrink,
it just crashes after a few seconds. There is no error
message from DVDshrink, you just get the standard
MS message "Your program has crashed, do you want to
send a report". I ran the disk through vobblanker
and it processed it without errors but I still don't
get sound at normal speed. PowerDVD plays it OK on my pc.

I did notice that the original VOB files are not
quite "full" sized, they are each about 50Mbytes
short of a gigabyte. (After processing with vobblanker
they are the normal size)

I'm wondering if anyone has any ideas of what I can
look at to try fixing this disk.

[jsoto]

Seems it is not well authored or there is a problem in the audio...

Things to check:
- Audio attributes. The ones stored in IFO and the actual ones (you can demux the audio with pgcDemux. i.e.)

Reauthor:
-Demux the VOB in their streams (can use pgcDemux) and remux again (use Muxman, IFOedit...)
-Replace the original PGC with the newly authored one


jsoto

[hf]

Sorry it took me so long to give an update. I haven't
had time to work on the file. I used pgcdemux to demux
the vob. I ended up with a VideoFile.m2v and AudioFile_C0.mpa.
When I tried to remux it with muxman, I get an error when
trying to import the audio file. The log file shows "Audio type
not recognized" Using winamp, realplayer, or windows media player
I could listen to the audio file. They report it as being 224Kbps
48Khz 2 channel. I see the pgcDemux log file has a line
"Audio_1=0x40" I don't know what that means exactly but
it seems odd.

Using pgcedit to look at the stream info from the original I get:
VTS 1 VOB streams attributes (VTS_01_0.IFO): 1 Audio, 0 Sub-picture streams.
- Video: 4:3 NTSC (720x480), MPEG-2 (VBR)
- Audio 0: --, unspecified, MPEG-1 (2 channels), Unspecified application mode

I've never done any muxing/demuxing before or audio resampling, so
I am at a losss for what to do next. Any help would be appreciated.

[mpucoder]

I could tell you a little more about it if I knew the first 4 bytes of the file.
Using VobEdit open up the original vob file, scroll down to the first audio and click on it. On the right side you'll see a line that says:
[001f] Audio-MPEG Frame
And further to the right is the contents. What does it say there for the first 4 pairs of numbers in square brackets?

[hf]

OK, using vobedit, the first audio pack is the 8th item in
the left hand pane, clicking on it, the "Audio-MPEG Frame"
value begins "ff fc b4 00" (decimal 255 252 180 0). This is
for VTS_01_1.vob.

[mpucoder]

Well, that's correct for mpeg audio. Are you sure you used the latest PgcDemux (1201) and Muxman (0.12c)? I just tried this myself (with a working mpeg audio DVD), and it demuxes properly, and Muxman accepts the audio file OK.

[hf]

OK, I started over, decrypted, demuxed and remuxed and everything
worked this time. I don't know what went wrong before!

The only problem is that the original VTS_01.n.VOB files contained
5 different programs and all I ended up with was the first.

I found this thread: http://forum.doom9.org/showthread.php?s=&threadid=88195
Which seems to explain fairly well exactly what I need to do,
so I'll give it a try.

UPDATE: I went thru all the steps outlined in the above mentioned
thread and rebuilt the disk. Unfortunately when playing it on my
standalone, I still only hear the audio when playing it at 1.5x speed!
Arrrgh!!!

To see if it was a problem with how VobBlanker was reassembling
the programs, I took the smallest program (about 17 meg) and
burned it to a disk, still no sound at 1x speed. These files are
the VIDEO_TS.* and VTS_01_*.* that muxman creates so there
is definately something still screwed up with this video after the
demux/mux operation.

[jsoto]

Originally posted by hf
I see the pgcDemux log file has a line
"Audio_1=0x40" I don't know what that means exactly but
it seems odd.
Yep, there is a small bug here, but only the logfile is affected.

jsoto

[hf]

So, does anyone have any more ideas on how to get this
disk to play correctly? As I said in my last post, after
demuxing and remuxing even the .vob file produced by
Muxman .12c do not play correctly. I could trim the small
17MB clip to a more managable size and email it to someone
if they want to try figuring out what is wrong with
the sound.

[mpucoder]

17 MB isn't too large for my email. Is that just the audio, or the entire clip? Anyway, you can send it to muxman (at) mpucoder (dot) com and I'll look at it.

[mpucoder]

Yesterday I received the files, and played them on PowerDVD without problems (but that doesn't prove much). So I burned them and they play OK on my standalones. Since audio playback at 1.5x speed is unusual (most DVD players mute the audio except for normal play) it sounds like the JVC standalone has a problem with mpeg audio.

[hf]

Thanks for looking into it. The JVC player has a
a nice feature where you can still hear the audio
at 1.5x speed. It is nice when you are watching
a slow movie to help speed up the plot! So I think
is quite strange that the JVC player gives no
audio at normal speed, but gives audio at 1.5x.

So I guess the next question would be is there
a program I can use to convert the audio stream
into something else? And what would that something
else be? I've never had to pay any attention
to the audio streams before, so I'm not really
sure what the normal audio encoding is for a dvd.

[Msc_Alex]

Try converting it with ac3machine (http://www.doom9.org/Soft21/Audio/AC3Machinev0.41.zip)
to ac3:)

[hf]

Thanks to everybodys help, I finally have a dvd backup that my
JVC player likes! I ended up demuxing each program with pgcdemux,
using ac3machine to convert each audio stream, remuxing everything
with muxman, and finally using vobblanker to replace the old streams
with the new. Now I can play the disk at normal speed and the narrator
no longer sounds like he had too much caffine :-)