Basic usage of ld decode

Decoding a raw RF LaserDisc sample

The following command example shows how to process a LaserDisc RF. This command demodulates the sample, frames it and then runs it through the digital TBC. The output file is suitable for use with a comb-filter:

python3 lddecode.py input.lds output -s 0 -l 25

python3 lddecode.py input.lds output --start 0 --length 25

python3 lddecode.py input.lds output --pal -start 0 --length 25

The syntax is input-file, output-file, start-offset (in frames) and frames-to-decode. So the example above starts at the beginning of the input file and processes 25 frames. Note that lddecode.py automatically adds the .tbc extension to the output video file.

In addition to the video file, the lddecode.py command will also output a .pcm file containing the analog audio information (if present). The .pcm audio output file is a raw PCM in 16-bit, 48KHz, 2 channel, little-endian format sound file.

You can view the output from the lddecode.py using the 'display' command:

NTSC: display -size 910x525 -depth 16 gray:output.tbc

PAL: display -size 1135x625 -depth 16 gray:pal2.tbc

Other lddecode options

Seeking

The -S option attempts to seek to an exact frame #. (-s is currently still used in conjunction for the starting raw location, and can be helpful when seeking in a full disk.)

Comb filter

NTSC

To process the output file from lddecode.py into a raw RGB file use the following command (for a 2D filter):

cat outputntsc.tbc | ./comb-ntsc -d 2 > outputntsc.rgb

or the following command for a 3D filter:

cat outputntsc.tbc | ./comb-ntsc -d 3 > outputntsc.rgb

You can view the raw RGB (NTSC) output from the comb filter using the following command:

display -size 744x480 -depth 16 rgb:output.rgb

PAL

To process the output file from lddecode.py into a raw RGB file use the following command (for a 2D filter):

cat outputpal.tbc | ./comb-pal -d 2 > outputpal.rgb

You can view the raw RGB (PAL) output from the comb filter using the following command:

display -size 974x576 -depth 16 rgb:output.rgb

Converting the RGB output into standard format pictures and video

To convert NTSC video into a series of PNG frames use the following example command:

convert -size 744x480 -depth 16 rgb:outputntsc.rgb ~/decodeout/frame$i.png

The example is similar for PAL:

convert -size 974x576 -depth 16 rgb:outputpal.rgb ~/decodeout/frame$i.png

There are two bash script commands included in the repository called encode-ntsc and encode-pal. These scripts provide an example of how to convert NTSC and PAL video and sound into a viewable AVI file using the ffmpeg command.