Laserdisc PCM Capture Guide

[schorman]

In my experience, the beginning and end of the disc are highly player dependent, and also somewhat random. Capturing five times will give you five different outcomes for that.

If you have a two sided player, you may find that playing on side B will give you more at the end of the disc, and playing on side A will give you a bit more at the beginning of the disc, or vice versa, or maybe just using side A, etc. That has been my experience with the Pioneer CLD D704, and the CLD 99.

I will typically capture once using side A, flip the disc and play again using side B, and then make a third capture if there are any inconsistencies (which doesn't have to be the whole side), just to squeeze as many samples as possible at the head and tail of the disc side.

Another trick is to start the capture and then rewind back to the beginning of the disc, as this will often give a bit more at the beginning of the side than if you just hit play. You can even do that a couple times to see if you get a bit more one time over another.

Obviously, the main place to be concerned with this is at the side changes. Missing a few milliseconds before the opening LD logos or at the end of the credits is not going to be overly detrimental. It's unlikely that even the LDdecode project can do this aspect perfectly, as it still relies on the player to set the start and end of each disc. Also, many older discs have quick side change logos at the beginning and end of every side, making it less important for those films.

[pipefan413]

In my experience, the beginning and end of the disc are highly player dependent, and also somewhat random. Capturing five times will give you five different outcomes for that.

If you have a two sided player, you may find that playing on side B will give you more at the end of the disc, and playing on side A will give you a bit more at the beginning of the disc, or vice versa, or maybe just using side A, etc. That has been my experience with the Pioneer CLD D704, and the CLD 99.

I will typically capture once using side A, flip the disc and play again using side B, and then make a third capture if there are any inconsistencies (which doesn't have to be the whole side), just to squeeze as many samples as possible at the head and tail of the disc side.

Another trick is to start the capture and then rewind back to the beginning of the disc, as this will often give a bit more at the beginning of the side than if you just hit play. You can even do that a couple times to see if you get a bit more one time over another.

Obviously, the main place to be concerned with this is at the side changes. Missing a few milliseconds before the opening LD logos or at the end of the credits is not going to be overly detrimental. It's unlikely that even the LDdecode project can do this aspect perfectly, as it still relies on the player to set the start and end of each disc. Also, many older discs have quick side change logos at the beginning and end of every side, making it less important for those films.

I suspected that might be the case! I haven't really seen any pattern in terms of one side reading more than another but simply capturing the same side on the same orientation inside the player has still read more or less depending on the instance of the capture. It really isn't important in most cases I've found so far but that's a small sample size and I'm extremely picky regardless (I suspect we are alike in that respect based on what I know about your own methods). As you say, it could be beneficial at the side change when there is no side change screen on either end in particular (e.g. NEAR DARK). I may investigate the rewind method and see if capturing the first wee chunk and last wee chunk differs at all depending on disc orientation!

[schorman]

I saw a definite tendency to get more audio at the end of a side when playing it on side B in my players. It's not programmed to flip sides in that case, which is why I think it will tend to play until the full disc ends, or at least closer to the end.

[pipefan413]

My soundcard is a Creative SoundBlaster SB0880 X-FI Titanium.

Is it just me, or does the Sound Blaster control panel keep switching "Enabled bit-matched recording" off every time you restart your system?

Everything else stays as is, but that one (crucial) setting keeps defaulting to off. If it's off, it resamples. If it's on, it's bit-perfect. A bit irritating!

[HippieDalek]

Is it just me, or does the Sound Blaster control panel keep switching "Enabled bit-matched recording" off every time you restart your system?

Everything else stays as is, but that one (crucial) setting keeps defaulting to off. If it's off, it resamples. If it's on, it's bit-perfect. A bit irritating!

Mine behaves the same, I'm not sure why it behaves like this, but I remember reading another guide (over on OT) where a user said:

"Anyway, I've found that the bit-matched setting in this card is a bit fragile, i.e. it's easily disturbed - for that reason it's best to switch it on at the very last minute."

So I only turn that setting on right before I press record.

[pipefan413]

Is it just me, or does the Sound Blaster control panel keep switching "Enabled bit-matched recording" off every time you restart your system?

Everything else stays as is, but that one (crucial) setting keeps defaulting to off. If it's off, it resamples. If it's on, it's bit-perfect. A bit irritating!

Mine behaves the same, I'm not sure why it behaves like this, but I remember reading another guide (over on OT) where a user said:

"Anyway, I've found that the bit-matched setting in this card is a bit fragile, i.e. it's easily disturbed - for that reason it's best to switch it on at the very last minute."

So I only turn that setting on right before I press record.

Hmm. Thanks for confirming it's not just me!

To be fair, I have also found that the sample rate setting on the USB interface (ESI U24XL) occasionally decides to reset to 48 kHz mid-recording, which is one of the reasons I thought I'd try the PCIe option instead. So I guess they're both a little flakey.

[BusterD]

Got an ESI U24XL the other day, and used it to capture my only DTS LD, the Japanese DTS LD of Hard Target (PILF-2647). schorman's link seemed to work fine as the resulting DTS file seemed the right length, but foobar would stop playback after searching to the 2nd half, and eac3to gave an error part way through when trying to decode to separate wav files.

But after editing the input wav file into 2 files for each LD side and trimming a bit of silence, Wav2Dts seemed to work fine on the files. Thank you bronan and schorman!

[BusterD]

Hmm, maybe I spoke too soon...
eac3to didn't produce any errors when converting the .dts files for each side to a separate .dts file (eac3to input.dts output.dts), but getting libDcaDec Invalid Bitstream Format errors toward the ends of the files when trying to convert them to separate .wav files (eac3to input.dts output.wavs).

I personally don't need to convert the files and don't have any project plans for Hard Target, but does this mean the capture is corrupt? The .dts files at least seem to play fine during a spot check in foobar.

[zoidberg]

I've had this happen, if you close eac3to when the error message appears the wav file won't be deleted.

[pipefan413]

Out of curiosity, might this just be because the ends are not rounded to whole DTS frames (512 samples at 48 kHz for example)? If so, could be fixed in hex editor or something easily enough, in theory.