

Overclocking the lecture: consume recorded lectures much more quickly - joshu
http://joshua.schachter.org/2008/11/overclocking-lecture.html

======
osipov
I'm in grad school and watch all my lectures using the approach described in
the blog post. After following this accelerated viewing approach for almost 2
years I can tell you that in reality the content doesn't get consumed "much
more quickly".

First, for most lecturers it isn't possible to listen to recordings more than
1.5 times faster. At this rate, there is a roughly 33% reduction in the time
it takes to view a lecture. It is noticeably faster, but not really
significant unless you are viewing more than 1 lecture at a time, for example
a lecture is typically 50 minutes, so one saves about 17 minutes per lecture.
In my experience the savings fail to realize for the reasons I'll cover
further.

Second, the rate at which the lecture can be accelerated varies significantly
depending on the professor who is presenting the material. Some professors
speak quickly and once the playback speed is increased to 1.5, their speech
becomes blurred and unintelligible. Often the native English speakers are the
ones who can't be sped up much. Luckily, at my school most of the professors
aren't native speakers so a rate of 1.5 is adequate. For non-native speakers,
the useful playback rate varies pretty widely. One of my professors who is
from Turkey speaks slowly and his lectures can be played and understood at a
speed up of 2.

Third, the playback speed does affect comprehension. Even at a normal playback
rate I find that some topics covered in the lecture require a rewind and a
replay. Accelerated playback requires closer attention and more frequent
replays. Of course how often one needs to replay the lecture depends on the
content and varies from person to person.

~~~
Hexstream
"Often the native English speakers are the ones who can't be sped up much.
Luckily, at my school most of the professors aren't native speakers so a rate
of 1.5 is adequate."

Luckily?... Think about it a few seconds. You don't get any more benefit from
listening to a slower speaker at a faster playback speed over a faster speaker
at an equivalently less fast playback speed. If you see what I mean...

~~~
osipov
>You don't get any more benefit from listening to a slower speaker at a faster
playback speed over a faster speaker at an equivalently less fast playback
speed

That assumes that you are comparing the same course being taught by a faster
speaker vs. a slower speaker. In reality, you don't have a choice. So if you
are stuck with a slower speaker, you might as well speed up their lecture.

~~~
Hexstream
I don't think you understood what I mean. I mean that if you have someone who
speaks at a rate of x and that gets unintelligible at a playback speed of y
and another that speaks at a rate of 2x and gets unintelligible at a playback
speed of y/2 then all other things being equal you have no advantage in
listening to one instead of the other if you playback at the maximum
intelligible speed.

------
Tichy
Reminds me of "Microserfs", when the protagonists took to watching foreign
movies on fast-forward, because they could still follow the subtitles.

~~~
joshu
I like that idea too.

------
joshu
i still want to find a way to do this with ffmpeg (for the video) and sox (for
the audio) plus maybe slide changeover detection, slide text recognition, face
detection (to remove motion from speaker) etc etc etc. Feels like fixed camera
video is not too hard to process...

