My Digital Kingdom

I built an Apple TV app for a practical reason: I wanted to manage my home media setup from the couch. What it became was so much more.

My “Digital Kingdom” is a collection of machines that each do one job well: the Apple TV is the control center, the Windows server manages media, and the Mac has become a shared AI appliance providing local Qwen, Whisper, and MCP services across my network.

At home I have three Apple TVs, a small always-on Windows mini PC that acts as a media server, and a Mac that handles local AI jobs. The more I used that setup, the more annoying it became to walk back to a computer just to search for something, move files around, attach subtitles, or check whether the server was running out of space.

BiffDownload started as a simple Apple TV front end for that media server. It has evolved into the keys to the “kingdom”: a Swift tvOS app, a Python API on Windows, a Python AI helper API on macOS, and a Linux machine that uses the Mac’s MCP and local AI services.

This is a follow-up to my earlier post, Local AI is Saving Me $, where I wrote about using local AI to process my personal photo and video archive. That post was mostly about cost and long-running AI jobs. This one is about the product layer around my home media setup: the Apple TV interface, the local APIs behind it, and the subtitle workflows that now run across machines on my LAN.

The Basic Idea

BiffDownload is not a replacement video player. I still use VLC on Apple TV for playback over DLNA/UPnP. BiffDownload is the control panel to manage the media.

From the Apple TV remote I can:

  • Search for media
  • Queue downloads to a chosen folder
  • Watch transfer progress
  • Browse and manage files on the server
  • Search for existing subtitles
  • Attach subtitles to videos
  • Generate new AI subtitles locally
  • Check server status and disk usage

The important part is that all of this happens from the TV. No remote desktop session. No laptop on the couch. No walking over to the media server for routine tasks.

Apple TV Demo

For the demo video, I used TPB AFK: The Pirate Bay Away From Keyboard (2013), a Creative Commons licensed documentary released by filmmaker Simon Klose. I chose it because it is legal to download and is widely available, making it good for demonstrating a download operation visually.

TPB AFK: The Pirate Bay Away From Keyboard (2013) Copyright Simon Klose | tpbafk.tv Licensed under CC BY-NC-ND 3.0

https://creativecommons.org/licenses/by-nc-nd/3.0

The Three Main Pieces

The system currently has three main services.

Apple TV App

The front end is a native tvOS app written in Swift. It is designed for the Apple TV remote, so the UI has to be clear from across the room and work well with focus navigation instead of a mouse or touch screen.

The app talks to the Windows API over the local network. It does not know how to run ffmpeg, talk to aria2, search OpenSubtitles, or mux subtitle tracks directly – those all happen on the Windows media server where the media library lives. It sends requests, polls job status, and presents the current stage to the user.

That separation made the app much easier to evolve. The Apple TV app can stay focused on workflow and feedback while the server handles the messy media operations.

Windows Media Server API

The Windows mini PC is the always-on machine. It runs the main Python API and owns the media library.

That API handles:

  • Search integration
  • Download queueing
  • File and folder operations
  • Transfer status
  • Disk information
  • Subtitle search through OpenSubtitles
  • Subtitle muxing
  • Audio extraction for AI transcription
  • Calling the Mac AI helper service

The API wraps these Windows command-line tools into simpler endpoints that the Apple TV app can use.

ProjectHomepage / DownloadPurpose
aria2https://aria2.org/High-performance command-line download manager supporting HTTP(S), FTP, SFTP, BitTorrent, and Metalink.
Prowlarrhttps://prowlarr.com/Indexer manager for Sonarr, Radarr, Lidarr, Readarr, and other *Arr applications.
Jacketthttps://github.com/Jackett/JackettTranslates searches from hundreds of torrent trackers into a standard Torznab API.
Subliminalhttps://subliminal.readthedocs.io/Python library and CLI for automatically finding and downloading subtitles from multiple providers.
FFmpeghttps://ffmpeg.org/Industry-standard multimedia toolkit for converting, transcoding, streaming, filtering, recording, and processing audio/video. Supports virtually every major media format.
MKVToolNixhttps://mkvtoolnix.download/Suite of tools for creating, inspecting, splitting, merging, editing, and modifying Matroska (MKV) files without re-encoding. Includes the popular mkvmerge and MKVToolNix GUI.

This is also where most of the orchestration happens. For example, when the Apple TV app asks for AI subtitles, the Windows API extracts the audio, sends it to the Mac API, receives the .srt, validates it, and then creates a new video copy with the subtitle track embedded.

Mac AI Helper API

The Mac runs a separate Python helper API for local AI work. For subtitles, it runs MLX Whisper on Apple Silicon. It also exposes local AI services backed by Qwen models, plus MCP services that Claude and Codex can use from other machines on my network.

The reason for splitting this out is simple: the Windows mini PC is great as an always-on file and download server, but the Mac is much better for local AI inference. Rather than force one machine to do everything, the Windows service sends the audio over the LAN and lets the Mac do the transcription work.

For a full-length movie, the Mac can usually generate subtitles in about 5 minutes—longer if the audio is in a non-English language and it triggers translation. That is fast enough for the way I use it, especially since the whole job can be started from the Apple TV and left alone.

The same Mac service layer is also useful outside the Apple TV workflow. Claude and Codex sessions running on other machines can reach back to the Mac for local model access, transcription tools, and MCP-backed utilities. That makes the Mac more like a shared AI appliance on the LAN than a single-purpose subtitle box. For example, my Linux machine can use MCP to keep repository documentation—such as README files—in sync with Obsidian notes stored in a vault on the Mac.

Two Subtitle Paths

Subtitles are one of the biggest reasons this project became useful. I have two different subtitle workflows now: a normal online subtitle search path and a local AI generation path.

OpenSubtitles Search

The first path uses the existing subtitle ecosystem. From the Apple TV app, I can select a video and search for matching subtitle files through the Windows API. The server uses subliminal to query OpenSubtitles, download a matching .srt, and then mux that subtitle into a new video copy.

That workflow is usually the best option when a good subtitle already exists. It is faster than AI transcription, and it avoids generating text that someone has already created and synced.

The Apple TV app treats this as a normal media-management task:

  1. Pick a video.
  2. Search for subtitles.
  3. Choose a result.
  4. Ask the server to attach it.
  5. Play the new copy in VLC.

This is the boring path—and that’s exactly why it matters. If OpenSubtitles has a good match, I do not need AI at all.

Local AI Subtitle Generation

The second path is for videos where I cannot find a good subtitle. That is where the Mac helper service comes in.

From the Apple TV, the AI workflow looks simple:

  1. Choose a video.
  2. Start AI subtitle generation.
  3. Watch the stages update.
  4. Review the result.
  5. Use the new subtitled copy.

Behind the scenes, the Windows API does a lot more:

  1. Probe the video with ffprobe.
  2. Extract a compact audio file with ffmpeg.
  3. Send the audio and source duration to the Mac API.
  4. Run MLX Whisper on the Mac.
  5. Receive the generated SRT file.
  6. Validate the subtitles.
  7. Mux the subtitle track into a new MKV copy.

The Apple TV app now shows the major stages in that pipeline:

  • Extracting audio
  • Uploading audio
  • Generating subtitles
  • Receiving subtitle file
  • Checking quality
  • Merging video

The result is that subtitle search and subtitle generation live side by side. The normal subtitle service is the first choice when it works. Local AI is the fallback when no good match exists.

Why the API Spec Became Important

One thing that made this project manageable was keeping API spec documents up to date.

The Windows API has a Markdown spec that describes the endpoints, request bodies, responses, job states, and examples. The Mac API has its own spec too, covering the local AI services, Whisper transcription endpoints, subtitle generation behavior, and the helper features used by other machines.

Those specs became the contracts between the Apple TV app, the Windows media server, and the Mac AI service. As I added features, I updated the specs and used them to keep the Swift app and both Python APIs aligned.

That mattered a lot because I was using AI coding tools across different parts of the system. Claude and Codex were used on macOS, Windows, and Linux to build it all. The Mac API also provides local Qwen-based AI services and MCP tools that Claude and Codex can use while running on other machines, so the documentation has to describe not just app endpoints, but also the shared AI services available on the network.

A Cool Agentic Coding Moment

One of the moments that really changed how I think about AI-assisted development happened while building this project.

From a single terminal window, Claude or Codex wasn’t just editing one codebase. It was coordinating work across my entire local development environment.

A single request could:

  • Modify the Python media server running on the Windows mini PC.
  • Update the Python AI helper API running on the MacBook Pro.
  • Add new Swift models, networking code, and UI to the Apple TV app.
  • Update the shared Markdown API specifications.
  • Build and test each component before moving on to the next.

From my perspective, I was still working in a single terminal window. Behind the scenes, the AI was making coordinated changes across three independent codebases running on different computers, communicating through well-defined APIs.

Tools In The Stack

The system uses a mix of regular media tools and local AI tools.

Apple TV

  • Swift
  • tvOS
  • Xcode

Windows Media Server

  • Python
  • aria2
  • Prowlarr
  • Jackett
  • subliminal
  • OpenSubtitles
  • ffmpeg
  • ffprobe
  • MKVToolNix / mkvmerge
  • PowerShell for service management

Mac AI Service

  • Python
  • MLX Whisper
  • Local Qwen AI services
  • MCP services for Claude and Codex
  • Apple Silicon
  • Local network API calls

Development

  • Claude
  • Codex
  • Markdown API specs
  • Generated HTML API test pages

Voice Cloning

I am completely amazed at how well voice cloning works locally on my machine.

Components

I already had a local MLX Whisper model running, which I use to generate subtitles from video. I thought that was all I needed. Then I asked Codex to build me a voice cloning tool in Python, and it went much deeper than I expected.

The tool ended up using:

  • Python
  • FFmpeg and FFprobe
  • MLX Audio text-to-speech
  • MLX Whisper transcription
  • Hugging Face model snapshots

Warning

Voice cloning needs to be handled responsibly. Permission, disclosure, and context matter. For this experiment, I used a historical public figure rather than cloning the voice of a living person.

What the Tool Does

  1. Lets me choose a reference audio or video file
  2. Lets me choose a speech text file
  3. Detects and skips leading silence (FFmpeg)
  4. Extracts and cleans a reference voice sample (FFmpeg)
  5. Transcribes the cleaned reference using an MLX Whisper model (whisper-large-v3-mlx)
  6. Generates new speech from text using a local MLX Audio model (higgs-audio-v2-3B-mlx-q8)

The wild part is that all of this runs locally. No cloud service. No subscription API. Just my Mac, some open-source tools, and a Python script that suddenly feels a little too powerful.

Local AI is Saving Me $

I have been experimenting with local AI for a practical reason: I wanted to make my personal photo and video archive searchable without paying cloud AI prices indefinitely. Cloud AI is faster and easier, but costs money each time and sends files to outside servers. Local AI runs on your own computer, so it is slower but more private and cheaper for repeated processing.

My collection is large enough to make this interesting: roughly 30,000 photos and videos gathered over many years. I originally stored them on Flickr, but the cost and export limitations became frustrating. One issue that stood out was Flickr’s migration tooling, including limits such as being unable to export albums with more than 500 photos at a time.

AI coding tools changed the equation for me. With Claude and Codex, I was able to migrate the media to AWS S3 and create apps to browse the collection on the web and on Apple TV.

The Problem

Moving the files was only part of the project. The bigger goal was search.

I did not want to search only by filename, date, or folder. I wanted to search by what was actually in the media:

  • “beach sunset”
  • “birthday party”
  • “dog in the backyard”
  • “old vacation video”
  • “kids opening presents”
  • “mountains with snow”

That requires descriptions, tags, and metadata for each item. For photos, this is fairly straightforward. For videos, it is more complicated because the AI needs representative frames or some kind of visual summary.

The Pricier Fix

A few months ago, I started a project to generate tags and short descriptions for the entire collection and store the results in MySQL.

My first version used cloud AI. I wrote Python scripts that sent images to the OpenAI API, received tags and descriptions, and saved the results back into the database.

Using an older model, GPT-5.2, I was able to generate about 30,000 sets of tags and short descriptions for the images. That worked, but it cost around $80 in API calls, and that was only for photos, not videos.

That cost was not outrageous for a one-time project, but it made me think differently. If I wanted to reprocess the archive, get more detailed descriptions, include videos, or run future batches, the cost would keep adding up.

Enter Local AI

While working on this, I started experimenting with local AI. On my machine, I don’t expect it to replace ChatGPT, Claude, or Codex, but I’m hoping to match that older GPT-5.2 model I paid for.

My local setup is simple:

Main AI machine

  • Apple M2 Max MacBook Pro, 2023
  • 32 GB RAM
  • 1 TB SSD
  • macOS

Long-running worker machine

  • Apple MacBook Pro, 2016 Intel i7
  • 16 GB RAM
  • 500 GB SSD
  • Ubuntu

The newer Mac runs the AI in macOS. The older Mac runs the long Python jobs in Ubuntu, so my main computer is not tied up all day and I can still use it for light processing tasks. The Ubuntu machine sends requests over the local network to the AI server running on macOS.

At first, I tried the usual local AI tools for Mac:

  • Ollama
  • LM Studio
  • AnythingLLM

I downloaded large Apple Silicon-optimized models, often in the 8 GB to 30 GB range, and tested them with chat, coding, and image-description experiments. On my hardware, the experience was not great. The models were slow, and the results were not impressive enough to justify the hassle.

Then I found this video and it changed everything!

That led me to try oMLX. It intelligently manages memory, which is the biggest bottleneck of running local AI.

Why oMLX Worked Better for Me

Some of the same models I had already tried felt much faster and more usable when loaded through oMLX compared with Ollama, LM Studio, and AnythingLLM.

What seems to make the difference is not just raw model speed, but how the stack uses Apple Silicon. MLX is built around the Mac’s unified memory architecture, and oMLX appears to make better use of that while also treating older context more like cacheable state than something that must stay fully resident in RAM at all times. For my workload, that matters more than benchmark bragging rights. I am sending resized images and a handful of video frames in long unattended batches, so a systemthat manages memory well and stays responsive under pressure is more useful than one that only feels fast in short interactive chats.

I am not running the latest Mac with 128 GB of memory – I am using a 32 GB M2 Max MacBook Pro from 2023, so memory pressure matters.

The tipping-point model for me was this model, on my machine, in oMLX:

Qwen3.6-35B-A3B-4bit

This model had barely been functional on my machine using Ollama/LM Studio/AnythingLLM. With oMLX, it became very usable – enough for long-running image and video description jobs.

It’s nowhere near today’s cloud models, but still useful enough for some tasks that don’t require higher thinking. It reminds me of where cloud models were roughly a year ago- around the time OpenAI was transitioning from GPT4 to GPT5.

The Cheaper Fix

The oMLX app makes it easy to startup the server, download models, and tweak the performance. Once I had the local AI server running, I started building Python scripts to query it.

The goal was to generate richer, larger descriptions for both images and videos, then save those descriptions into a new database. For videos, the script uses FFmpeg to extract sample frames and sends those frames to the local model as visual context. A simpler operation will follow to migrate that data where I host the image information.

The workflow looks like this:

  1. The Ubuntu machine runs a Python script.
  2. The script reads media records from MySQL.
  3. For images, it resizes the image to a practical size before sending it to the AI model.
  4. For videos, it extracts five frames with FFmpeg.
  5. It also extracts and stores exif data using ExifTool.
  6. The script sends the image or video frames to the oMLX server running on the Mac.
  7. The local model returns a content description and tags.
  8. The script stores the result in MySQL.
  9. If the script stops, it can resume later without starting over.

Here is the basic idea of the video prompt:

Local AI Test

Before I started building this out, I used OpenCode to test the local AI model’s ability with the prompt above. I captured the session in the clip below, which also reveals the video content that was analyzed.

Result

The frames show a young boy wearing a white suit dancing at an outdoor nighttime birthday party. A decorated banner reading “Happy 50th Birthday Minnie” with colorful illustrations is hung on a block wall behind him. Colored party lights—red and green—cast spots on the wall as the boy moves across the concrete patio, appearing to dance. Several other people, including adults and possibly other children, stand to the right watching, with one person in a plaid shirt partially visible. Large leafy plants or bushes are visible to the right of the wall.

The Plan

The full plan is to let the Ubuntu machine run for days if necessary while the M2 Max handles the local AI requests.

The script will:

  • Traverse the database of roughly 30,000 images and videos.
  • Resume safely if the process is stopped or interrupted.
  • Use ExifTools to collect camera and location metadata where available.
  • Use FFmpeg to extract five representative frames from each video.
  • Query the local oMLX AI server for image and video content descriptions.
  • Store the generated descriptions and metadata in a new MySQL table.

The important part is that I am no longer paying per image or per video, and can run more computationally expensive queries such as full 1-2 paragraph image descriptions. Once the local AI setup is working, the cost is mostly electricity, heat, and time.

Challenges

This was not plug-and-play. I had to do a fair amount of tuning.

One issue was image size. Some of the images being sent to the local AI model were too large, which created context window and memory problems. That may also explain why the earlier cloud API run became more expensive than expected.

I asked Codex to recommend a practical image size for tagging and description generation. The script now resizes images before sending them to the AI server. The resized images are still good enough for recognition, but they are much easier on the model.

I also used ChatGPT to analyze my oMLX server logs and help tune performance settings, including:

  • Context window
  • Maximum tokens
  • Concurrent requests

Heat was another issue. During long runs, the MacBook Pro can get hot from sustained CPU, GPU, and memory usage. To reduce stress on the machine, I added a five-minute cooldown after every 500 requests.

This makes the 6-day job take 4 hours longer, but that is acceptable. The whole point of this setup is that it can run unattended.

Current Results

It is working.

The current run is slow, but steady. With around 30,000 media items and an average of roughly 22 seconds per item, the full job should take 6 days or more with breaks.

That sounds terrible compared with cloud processing, but it changes the economics. I can stop, tweak prompts, retry batches, and improve the database without watching a meter run.

For my use case, local AI does not have to be instant. It just has to be good enough, reliable enough, and cheap enough to keep running.

What I Learned

Local AI (for my hardware) is more powerful than I expected, but is much slower than cloud-models and takes more setup. Even so, local AI has its own advantages:

  • No per-request cost
  • Ability to reprocess data without paying again
  • Useful performance on consumer Apple Silicon hardware
  • A good fit for long-running batch jobs

For a project like tagging and describing a lifetime of personal photos and videos, that tradeoff makes sense.

Another surprising part is that older hardware still has a role. My 2016 Intel MacBook Pro is not running the AI model, but it is perfect as a worker machine that can run Python scripts all day. The M2 Max does the AI work, and the Ubuntu laptop keeps the pipeline moving.

That combination turned out to be exactly what I needed: one machine for local AI, one machine for automation, and no cloud bill for every experiment.

Generate Subtitles for Your Videos Free with AI

The audio in this video contains several languages and subtitles were generated using the process described in this post.

I recently watched a movie on Netflix with scenes in multiple languages: English, Korean, French, and Italian. During the foreign language scenes, there was no translation, just the name of the language spoken, like “[Korean]”. How disappointing…

In a nerdy fit of revenge I decided to fix this myself. So, I obtained an .mp4 video file of the movie and went to work. The tech I’m about to describe uses AI to listen to your movie’s audio, translate it from almost any language, and create subtitles. You could also use these tools for other tasks such as generating lyrics for music.

The tools involved are a combination of ffmpeg and mlx-whisper – a version of OpenAI’s Whisper model optimized to take advantage of Apple Silicon chips. The hour and a half movie I mentioned took less than 5 minutes to generate subtitles on my Apple M2 Max Macbook Pro with 32Gb of memory. I asked ChatGPT what makes mlx-whisper faster on Apple Silicon chips and this is what it said:

What you’ll need

  • A modern Mac using Apple Silicon
  • The Terminal app

This is how you get ffmpeg and mlx-whisper on your Mac.

  1. Brew
    • https://brew.sh/
    • On the web page, you can copy the install command for your terminal
      • /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
    • Follow the resulting instructions displayed in the terminal to make brew into a command. These were mine, specific to my user name on the machine. Copy yours from the terminal
      • echo >> /Users/bubba/.bash_profile
      • echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> /Users/bubba/.bash_profile
      • eval "$(/opt/homebrew/bin/brew shellenv)"
    • Give it a quick test- type brew and hit return to see if works
  2. FFMpeg
    • brew install ffmpeg
    • Give it a quick test by typing ffmpeg and hit return
  3. Python
  4. Pip
    • Download the script from https://bootstrap.pypa.io/get-pip.py into a folder you can run the terminal from. You can also right-click the link and save it
    • python3 get-pip.py
    • Give it a quick test by typing pip and hit return
  5. MLX-Whisper
    • pip install mlx-whisper
    • Give it a quick test by typing mlx_whisper and hit return
  6. LLM – a 3 Gigabyte Large Language Model
    • pip install huggingface_hub hf_transfer
    • export HF_HUB_ENABLE_HF_TRANSFER=1
    • huggingface-cli download --local-dir whisper-large-v3-mlx mlx-community/whisper-large-v3-mlx
    • use a folder where the video will reside

Now that that ffmpeg and mlx_whisper are installed, along with the LLM, lets assume you have a video to subtitle, called input.mp4.

To create an external subtitle file in the .srt format:

mlx_whisper input.mp4 --task translate  --model whisper-large-v3-mlx --output-format srt --verbose False   --condition-on-previous-text False

You can open the .srt file with a text editor and take a look, as well as make manual edits if desired. Now, you can either overlay the subtitle into the video, or add it as a track, so you could turn it on/off when viewing the video.

To overlay the subtitle into the video:

ffmpeg -i input.mp4 -vf subtitles=input.srt -c:a copy output.mp4

To add the subtitle as an optional track instead:

ffmpeg -i input.mp4 -i input.srt -c copy -c:s mov_text output.mp4

Now, suppose you wanted to do this to a folder of .mp4 files. You could loop through them with a shell script. I created this one and it worked for me:

#!/bin/bash

# Loop through all .mp4, .mkv, and .m4v files in the current directory
for video in *.mp4 *.mkv *.m4v; do
  # Skip if no matching files are found
  [[ -e "$video" ]] || continue

  # Extract the file extension and base name
  ext="${video##*.}"
  base="${video%.*}"
  subtitle="${base}.srt"

  echo "Subtitling: $video"
  mlx_whisper "$video" --task translate --model whisper-large-v3-mlx --output-format srt --verbose False --condition-on-previous-text False
  sleep 3

  # Check if the matching .srt file exists
  if [[ -f "$subtitle" ]]; then
    output="${base}_subtitled.${ext}"
    echo "Creating video: $output"
    echo " from subtitle: $subtitle"
    ffmpeg -i "$video" -i "$subtitle" -c copy -c:s mov_text "$output"
  else
    echo "Subtitle not found for $video"
  fi
done

Because my media player can play .mp4, .mkv, and .m4v files, and they all work with these commands, I also added those formats into the loop.