#29 No audio when using libdv with PAL D-VHS

[Anonymous]

Raw DV files generated by libdv come out silent on
my PAL D-VHS deck.

There appears to be sound in the files, as playdv will
play and extract it,
but the D-VHS deck mutes when the signal is fed into
it. The video is OK.
As the D-VHS format natively supports stereo 48kHz
sound, I haven't tested
any of the 32kHz modes.

To demonstrate I've attatched two raw PAL DV files.
Video is the same
in both files and is probably irrelevant as libdv didn't
create it. For
these tests I'm using v0.98, but it's been the same
since at least
version 0.7 when I started using it.

Sound.dv was created by merging video and a 48kHz
stereo wav file in
Ulead Video Studio and then exporting a Type 1 DV
AVI. This was then
converted to raw DV by using dvavi. Sending this to
the D-VHS deck works.

NoSound.dv is the result of using insert_audio to
merge in the same wav
file with the above. Sending this to D-VHS gives video
but no sound. You
get the same result if you export a Type 2 DV AVI and
run dvavi on that.

There's something in the way libdv encodes the audio
that the D-VHS deck
doesn't like, but I haven't been able to discover
exactly what the
critical difference is.

[Nobody/Anonymous]

Logged In: NO

Sadly I'm unable to attach the files, as even two single
frame PAL DV files are greater than the 256,000 byte
attachment limit.

If you e-mail me at
dariush@rowlands2000.freeserve.co.uk I can forward the
attachment, or ftp it somewhere.

Cheers,

Dariush

[Nobody/Anonymous]

Logged In: NO

Sadly I'm unable to attach the files, as even two single
frame PAL files are greated than the 256,000 byte limit.

E-mail me at dariush@rowlands2000.freeserve.co.uk
and I can forward or ftp them somewhere.

Cheers,

Dariush

[Dan Dennedy]

Logged In: YES
user_id=78682

This appears to be similar to another problem report by a
Kino user. Whenever, he exports a new DV file while updating
the metadata (recording date/time and timecode) or renders a
DV transition, he is unable to transmit it properly back to
his Canon DV camera. However, it works with my Panasonic
camera and apprantly for others. There might be a bug
somewhere in the metadata writing of the encoder, but I feel
it will be difficult to track down.

[Nobody/Anonymous]

Logged In: NO

That explains a lot. Differences in metadata would
naturally lead to inconsistent differences between test
files. Is the same information repeated in each frame, or
does it build up gradually over a sequence of several?

The D-VHS deck has been deliberately engineered not to
export DV and metadata isn't even mentioned in the
manual. How can I go about extracting/displaying and
setting metadata in a given stream? Do you have a tool
for this?

If I could find out what it is in the 'working' streams, it
would then be possible to manually set some date/time
info which the deck will then accept. Since I don't need
valid metadata in there I could perhaps add some kind of
switch (e.g., --fake-metadata) to toggle the insert of
this 'dummy' data which would over-ride anything that
libdv would otherwise generate.

Does this sound plausible?

Dariush.