Upload the recording you already have — downloaded from your course portal, a Zoom cloud recording, or a MOOC — and get slide-by-slide notes, a full transcript, and a summary without watching it again.
No download needed · No credit card required · Mac app for macOS 14+
Ten weeks of lectures is twenty or more hours of video. Nobody has time to re-watch all of it, even at double speed.
Course portals give you captions at best: a wall of text with no structure, no headings, and none of the slides.
When you only need the formula from week four, you still have to scrub through the whole lecture to find where it appeared.
MP4, MOV, M4V, MKV, AVI, WebM, or MPEG up to 5 GB. Before anything uploads, LensNote checks the length against your plan, so you never wait on a file that cannot be processed.
Slide detection, transcription, and alignment run in the cloud. Once the upload finishes you can close the tab; recordings of 30 minutes or longer email you when the notes are ready.
The structured report walks through each slide with what the lecturer said about it. Click any slide to play the original moment.
The structured report as a PDF or an editable Word document, the slides as a PPTX deck with the notes in the speaker notes, or the transcript as plain text.
This is what LensNote produces from one recorded lecture: every slide once, its key message, and the words spoken while it was on screen. Click a slide to read its notes.
Raft keeps a cluster of servers agreeing on one log, even when some of them fail.
What was said · 00:00“Today is about one question: how do five machines agree on the same sequence of commands when any of them can crash?”
If every server applies the same commands in the same order, they all end up in the same state.
What was said · 03:42“Think of the log as a recipe. Follow the same steps in the same order and every kitchen ends up with the same dish.”
The leader-election process begins when a follower stops receiving heartbeats from the current leader.
What was said · 06:14“When a follower reaches its election timeout, it increments its term and becomes a candidate.”
Random election timeouts make it unlikely that two followers start an election at the same moment.
What was said · 11:08“Randomized timeouts are what prevent split votes from repeating forever.”
A log entry is committed once a majority of servers have stored it, and then it is never lost.
What was said · 15:56“Once three of our five servers have written the entry, we can safely tell the client it succeeded.”
Raft solves consensus by electing a single leader that orders every write. Followers start an election when heartbeats stop, and random timeouts keep elections from colliding. An entry is committed once a majority stores it, which is why committed data survives the loss of a leader.
A single leader turns agreement into a simple rule: the leader decides the order of the log and everyone else copies it.
Followers wait a random 150–300 ms before campaigning, so one candidate usually asks for votes before any other wakes up.
An entry stored on a majority of servers is committed; any future leader must already hold it, so it is never lost.
The full report continues section by section, with each slide placed as a figure.
One slide per key frame as an image, with the key message, bullets, and explanation in the speaker notes.
The structured report: a cover with the executive summary, then each section with its slides as figures.
The same report as an editable DOCX file, for rewriting in your own words.
The full timestamped transcript as plain text, for Notion, Obsidian, or a doc.
Turning a lecture recording into notes in LensNote produces four connected views of the same class, all aligned to one timeline, so you can move between them without losing your place.
The Slides tab shows a filmstrip of every captured slide and the selected one at full size, labeled with its timestamp. Next to it, the Key points panel shows the slide’s key message, up to three bullet points, and the part of the transcript spoken while it was on screen. The Transcript tab lists the whole lecture with timestamps. The Summary tab collects the key takeaways and any action items, such as assignments the lecturer mentioned.
Finally, the Report tab walks through the lecture section by section: an executive summary first, then each part of the class with its slides as figures. This is the view most students use for revision, and it is what the PDF and Word exports contain.
Notes generated by AI are a starting point, not the final word, so every part of a LensNote session links back to the source. Click Play on a slide and the recording starts at the moment that slide appeared. Click any transcript line to hear it again.
That link changes how you revise. Instead of re-watching a 90-minute lecture, you read the slide-by-slide notes and replay only the two or three moments you did not understand, for as long as it takes to resolve them.
Most lecture recordings live in a learning platform such as Canvas, Moodle, Blackboard, or Panopto, or in a Zoom cloud recording. When the platform offers a download, save the MP4 file and upload it to LensNote; MP4, MOV, M4V, MKV, AVI, WebM, and MPEG are all supported.
Some courses only let you stream a recording. In that case, and where your course policy allows recording, play the lecture in your browser and record the playback window with the LensNote macOS app. LensNote does not import links directly, so a downloaded file or a screen recording is always the route in.
Clear audio matters more than anything else. A lecture recorded from the room microphone or a headset transcribes far better than one captured across a noisy hall. Slide capture works best when the slides fill most of the frame. Screen recordings made with the macOS app tolerate cursor movement and small overlays, but a tiny slide in the corner of a camera shot gives less to work with.
Long lectures are split into parts of about 45 minutes and processed in parallel, and a lecture full of near-identical frames is thinned out so the deck stays readable. If a recording has no audible sound, you still get visual notes without a transcript; if no slides are found, the recording is treated as an audio session with a transcript and summary.
Read next: How to extract slides from a video
Converted notes are most useful when you test yourself on them. A simple routine works: skim the slides and key messages within a day of the lecture, write your open questions, and each week try to explain the key messages from memory. Before the exam, replay only the timestamps behind the questions you still miss.
For more on study methods, read how to take lecture notes with the Cornell and slide + explanation methods, and how to take notes from a video lecture with timestamps, both on the LensNote blog.
Read next: How to take lecture notes · How to take notes from a video lecture
Video: MP4, MOV, M4V, MKV, AVI, WebM, and MPEG up to 5 GB. Audio: MP3, WAV, M4A, AAC, FLAC, OGG, OPUS, and WebM up to 2 GB. Audio-only files produce a transcript, a summary, and a summary image instead of slides.
LensNote processes files; it does not fetch links. If your course allows it, record the playback window with the LensNote macOS app, which captures the video and system audio together.
It depends on the length of the recording. Once the upload has finished you can close the tab: processing keeps running, and recordings of 30 minutes or longer send an email when the notes are ready.
Pro subscribers can buy a long-video pass that lifts the limit to 8 hours for a single video.
Yes. Your notes, slides, and transcripts stay viewable on the free plan. On the free plan, original video files are removed 14 days after upload.
New to LensNote? Start with the AI lecture note taker overview, see every use case in the AI note taker guide, or read the documentation.
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