Lab 4

Final project for W23 COM SCI M152A: Introductory Digital Design Laboratory.

Converter

Setup

Requirement: Python 3.8+

After checking out to this branch, set up the necessary dependencies:

python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

You will also need FFmpeg installed. You can probably obtain it using your local package manager. For Windows, you can download a static build and place the ffmpeg.exe binary some place on your PATH. I used the Chocolatey package manager for Windows instead:

# In an elevated PowerShell session:
choco install ffmpeg

Overview

The following graphic shows the different file formats into which an input MP4 file is transformed:

flowchart TD;
  mp4[foo.mp4\nOrdinary video file];
  rgb[foo.rgb\n40x30px RGB24 2fps];
  bin[foo.bin\n40x30px 8-bit VGA pixels 2fps];
  txt[foo.txt\n8-bit VGA pixels as array assignments];
  v[foo.v\nSource file containing hard-coded array];
  mp4-.-> |serialize.py: ffmpeg| rgb;
  rgb-.-> |serialize.py: numpy| bin;
  bin-.-> |transpile.py: numpy| txt;
  txt--> |copy-paste| v;

Serializing

I provided Makefile rules as front-ends for invoking my serialize.py/transpile.py scripts for building each format from the original MP4 file. Suppose it is named foo.mp4.

• make foo.rgb: Convert to a 40x30px resolution, 2 frames-per-second, RGB24 file.
• make foo.bin: Convert to a 40x30px resolution, 2 frames-per-second, 8-bit VGA color-encoded (rrrgggbb per pixel) file.
• make foo.txt: The same video properties as the .bin format but outputted as Verilog array assignment statements intended to be copy-pasted into a source file to be uploaded to the FPGA.

foo.txt is the final product we want at this step, and it's the file we can transfer onto a flash drive and then onto the host machine of the Xilinx ISE.

Visualizing

For debugging, you can use the show.sh script as a shortcut for invoking my visualize.py script, which takes any of the binary formats above and displays in a GUI the specified frame. Both frame numbers are seconds into the video are supported. For example:

# Show the frame 8 seconds into foo.mp4:
./show.sh foo.mp4 -s 8
# Compare the coloring of the 200th frame (assuming 2fps):
./show.sh foo.bin -f 200 & ./show.sh foo.rgb -f 200 &
# Confirm that a frame txt file has the right bytes:
./show.sh foo -f 0x30 & ./how.sh foo.bin -f 0x30 &

Cleanup

To clean the directory of binary and .txt intermediates, simply run:

make clean

Original MP4 video files as well as the TGZ distributables are preserved.