Domesday Duplicator Gain Settings for specific laserdisc players

For the Domesday Duplicator gain setting, here are some values I've discovered through trial and error.

See: https://www.domesday86.com/?page_id=2233#Gain_configuration

NOTE: The first number is switch 1 (so 1000 means switch 1 is on, the rest are off)

LD-V4300D:
LD-V8000:

    1000    (8.5 gain)

 

CLD-V2600:

• 0100 (6 gain if the disc isn't full length; will cause slight clipping at the end of a full length disc) 
• 0010 (4.4 gain if the disc is full length) 
  

Resistor/Gain

Switch 1: R406, 1.5k

Switch 2: R407, 1k

Switch 3: R408, 680

Switch 4: R409, 560

Some values just for clarity:

I had some success trying to get the audio from a Firefox laserdisc capture synced up to the video (which is actually a surprisingly hard problem to solve).

How to calculate the duration of NTSC lines and fields

I don't want to have to figure this out again, so here is the "exact" length of one horizontal line in microseconds.  If you want seconds, remove the 1,000,000 number.

H = (1001 * 1000000 * 2) / (1000 * 60 * 525)

(this can be simplified down to 4004/63)

The "exact" length of one field (ie space between start of two adjacent vsync pulses) in microseconds is:

V = (1001 * 1000000) / (1000 * 60)

(simplified down to 50050/3)

SD card CRC algorithm explained in detail

Recently, someone asked me to explain the SD card's CRC algorithm.  I had forgotten a lot so I was not able to tell him much but I got curious and decided to document exactly how it works here on this blog post so I can refer to it later.

First of all, the official SD card documentation (in section 4.5 as of the time of this post) briefly describes the CRC algorithm and gives a few examples.  Unfortunately, its description assumes that the reader is a math major in a masters program at a prestigious university rather than provide a simple algorithm that would make sense to a novice software developer :)

The wikipedia article ( http://en.wikipedia.org/wiki/Cyclic_redundancy_check ) is a bit more friendly and gives a helpful example.

SD cards use two CRC algorithms: one is called CRC7, the other is called CRC16.  I will explain CRC7 here.  CRC16 is the same except its "polynomial" is different as is the amount of padding that the initial number must receive.

The polynomial for CRC7 is 0x89; the polynomial for CRC16 is 0x1021 which is based upon a standard called CRC-CCITT.  More about that here.

The CRC7 algorithm works like this:

- Pretend that the data buffer you want to compute CRC7 from is a really huge number (big endian).
- Take this number and shift it left the number of bits that the result will have, in this case 7. (this seems to be standard for most CRC algorithms)
- Find the first bit (starting from the left) that is a 1 in the number and XOR that with the polynomial (where the polynomial is shifted left enough times that its highest bit lines up with the 1 that you found, I will provide an example later)
- Repeat the last step until the original number of bits (before you shifted it left by 7) are all 0's.
- The CRC result will be in the bottom 7 bits at this point.

Here is an example of how to get the CRC7 result that the SD card specs say you should get.

How to create AVCHD styled media from HDV

I have a camcorder that records AVCHD (ie x264 1080p) video which I can then put on an SD card and play in my blu-ray player.  This is very handy for showing home movies to my family that I've recorded.

But what about my older HDV movies?  It is much less convenient to hook up my older HDV camera and play the digital tapes on my TV.  I'd much rather use the same SD card trick that I use with my newer camcorder.

Here's how to convert HDV videos to a format that will work on my blu-ray player (and presumably others) and also my newer camcorder.

1 - download MultiAVCHD (see http://www.afterdawn.com/guides/archive/create_avchd_and_blu-ray_discs_with_multiavchd.cfm for a guide) .  I am using build 771.

2 - Get the test program and install dependency libs/programs from this link: http://multiforum.deanbg.com/viewtopic.php?f=7&t=17

Make sure the test program is passing all its tests.

3 - from the "Settings" tab, I used all defaults (except the destination folder).  You can mess with 64-bit x264 if you are brave.

4 - click on the "media" tab and "Add Video files".  Add your .m2t files you extracted with your HDV camera.

5 - your .m2t files should show up in a window below the "Add Video Files" button.  Select them all (might have to do this one by one) and click "Transcode"

6 - Change the "Resize" drop-down in the upper right to 1920x1080 (I had to scroll down).  UPDATE: Changing the resize default of 1440x1080 may not be necessary.

7 - The bitrate for mine defaulted to about 25000, I just left it at this default.

8 - As for quality, I've tried both "1 pass Turbo" and "2 pass VHQ" and both worked.  So if you are in a hurry, use 1-pass, if you want quality, use 2 pass.

9 - click "Apply"

10 - close the "properties" dialog by clicking "ok"

11 - click "Start"

12 - a new dialog will pop up.  Choose "TV / Camcorder (NTSC / 60 Hz)"

13 - good luck!

Been doing some video capturing lately

I've been capturing some S-VHS tapes lately and this gave me a chance to try out the Neat Video plugin which I bought a while ago.  It does quite a good job of cleaning up the noise from these old analog tapes.  I wonder if it could also handle Super8?  Here is just a quick screenshot of my preliminary results.  You can see the difference.