Simon Willison’s Weblog


Thursday, 13th June 2024

PDF to Podcast (via) At first glance this project by Stephan Fitzpatrick is a cute demo of a terrible sounding idea... but then I tried it out and the results are weirdly effective. You can listen to a fake podcast version of the transformers paper, or upload your own PDF (with your own OpenAI API key) to make your own.

It's open source (Apache 2) so I had a poke around in the code. It gets a lot done with a single 180 line Python script.

When I'm exploring code like this I always jump straight to the prompt - it's quite long, and starts like this:

Your task is to take the input text provided and turn it into an engaging, informative podcast dialogue. The input text may be messy or unstructured, as it could come from a variety of sources like PDFs or web pages. Don't worry about the formatting issues or any irrelevant information; your goal is to extract the key points and interesting facts that could be discussed in a podcast. [...]

So I grabbed a copy of it and pasted in my blog entry about WWDC, which produced this result when I ran it through Gemini Flash using llm-gemini:

cat prompt.txt | llm -m gemini-1.5-flash-latest

Then I piped the result through my ospeak CLI tool for running text-to-speech with the OpenAI TTS models (after truncating to 690 tokens with ttok because it turned out to be slightly too long for the API to handle):

llm logs --response | ttok -t 690 | ospeak -s -o wwdc-auto-podcast.mp3

And here's the result (3.9MB 3m14s MP3).

It's not as good as the PDF-to-Podcast version because Stephan has some really clever code that uses different TTS voices for each of the characters in the transcript, but it's still a surprisingly fun way of repurposing text from my blog. I enjoyed listening to it while I was cooking dinner.

# 1:03 am / pdf, podcasts, projects, text-to-speech, ai, openai, generative-ai, llms, gemini

Optimal SQLite settings for Django (via) Giovanni Collazo put the work in to figure out settings to make SQLite work well for production Django workloads. WAL mode and a busy_timeout of 5000 make sense, but the most interesting recommendation here is "transaction_mode": "IMMEDIATE" to avoid locking errors when a transaction is upgraded to a write transaction.

Giovanni's configuration depends on the new "init_command" support for SQLite PRAGMA options introduced in Django 5.1alpha.

# 5:04 am / django, sqlite

tantivy-cli (via) I tried out this Rust based search engine today and I was very impressed.

Tantivy is the core project - it's an open source (MIT) Rust library that implements Lucene-style full text search, with a very full set of features: BM25 ranking, faceted search, range queries, incremental indexing etc.

tantivy-cli offers a CLI wrapper around the Rust library. It's not actually as full-featured as I hoped: it's intended as more of a demo than a full exposure of the library's features. The JSON API server it runs can only be used to run simple keyword or phrase searches for example, no faceting or filtering.

Tantivy's performance is fantastic. I was able to index the entire contents of my link blog in a fraction of a second.

I found this post from 2017 where Tantivy creator Paul Masurel described the initial architecture of his new search side-project that he created to help him learn Rust. Paul went on to found Quickwit, an impressive looking analytics platform that uses Tantivy as one of its core components.

The Python bindings for Tantivy look well maintained, wrapping the Rust library using maturin. Those are probably the best way for a developer like myself to really start exploring what it can do.

Also notable: the Hacker News thread has dozens of posts from happy Tantivy users reporting successful use on their projects.

# 6:03 am / fulltextsearch, search, rust

Transcripts on Apple Podcasts (via) I missed this when it launched back in March: the Apple Podcasts app now features searchable transcripts, including the ability to tap on text and jump to that point in the audio.

Confusingly, you can only tap to navigate using the view of the transcript that comes up when you hit the quote mark icon during playback - if you click the Transcript link from the episode listing page you get a static transcript without the navigation option.

Transcripts are created automatically server-side by Apple, or podcast authors can upload their own edited transcript using Apple Podcasts Connect.

# 8:14 pm / accessibility, apple, podcasts, transcripts