As we know, podcast is a very convenient way to use your commute time to get some useful information.

Recently, we have published a non-commercial podcast called Tunight, which collects interesting lectures and talks, aiming to provide a fast and easy way for those who cannot attend those activities to get an update.

For now, it runs well.

Soon we found out that some lectures cannot be easily understood without slides from lecturer. So we managed to get slides from them afterwards, like this lecture.

But we are not satisfied still. There is no sync mechanism between audio and slides.

In fact, slideshare.net once provided a service called Slidecast, but it died at year 2014.

So, what I need now, is a good video encoder optimized for Slidecast.

It takes Timestamps , PDF Slides and Audio, generates Video file to publish via podcast.

Why video? Because the best format podcast supports for 'Slidecast' is video. If we defined another standard just for 'Slidecast', I don't think it will get popular in short time. Plus, there are plenty of podcast clients on PC, Android, and iOS.

What is Timestamps? I don't know yet. But my recorder seems to support T-Mark function when recording. I can press the T-Mark button when speakers flip over their slides. Basically Timestamps are pure text files.

The most important part is encoder. We need to find a effcient video encoder optimized for slides. We have to tune the key frames distance of video encoder, so as to decrease video file size and increase video quality. File size can be a big problem when podcasting. No one wants to subscribe a podcast episode with a 400MB video file with a fuzzy image. For example, Camtasia seems to have a customized video encoder for screencast. Maybe we can get some hints from them.

In summary:

Timestamps (TXT) -+
PDF Slides       -+----- Optimized Encoder (eg. in form of FFmpeg) --> Video  --> Publish via Podcast
Audio            -+