Readme instructions

README.md

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 # readabletranscripts
-Readable YouTube Transcripts using Gemini Nano in Chrome
+
+This repo shows how to fetch the raw YouTube transcripts and use the Gemini Flash 8B API to format them.
+Made by [ldenoue](https://twitter.com/ldenoue)
+
+# How to use
+
+open https://github.com/ldenoue/readabletranscripts and type any search term
+
+click on the video, e.g. https://ldenoue.github.io/readabletranscripts/?id=8yzmCt0QwOQ
+
+You will see a summary of the video and the transcript below.
+
+# How it is done
+
+## Breaking the transcript into chunks
+We break up the raw YouTube transcript into chunks of 512 words.
+We feed each chunk to Gemini with a prompt (see https://github.com/ldenoue/readabletranscripts/blob/5c51f5298f9f39bc2f35a94b84baa95fa95408bd/code.js#L410)
+
+Notice that we send the requests in parallel to Gemini.
+
+## Merging sentences at the boundary between 2 chunks
+Once we have the formatted chunks, we now need to merge them.
+For each 2 consecutive chunks `chunk1` and `chunk2`, we ask Gemini to merge the last sentence `chunk1` and the first sentence of `chunk2` (see prompt in https://github.com/ldenoue/readabletranscripts/blob/5c51f5298f9f39bc2f35a94b84baa95fa95408bd/code.js#L433)
+
+We merge the chunks and the seams between them to obtain the final transcript.
+
+## Linking the raw YouTube timestamps with the final transcript
+
+In order to highlight the words as the video plays, we need to align the words from the raw YouTube transcript and the final, punctuated, transcript.
+
+We rely on `diff.js` for that.
+
+Now words get highlighted as the video plays, and users can also jump into the video by clicking any word in the transcript.
+
+