The VideoLAN Forums

I've some suggestions for you:
When using the video navigation slider (position in the video), it would be nice if a over the slider a little preview picture could be shown, while the video stays playing.

Example:

1. Start a video
   You want to access a special position in the video which you roughly remember
   Move the slider approximately to the middle of the video, using the left mouse button -pressed down-, while doing a little preview picture of the marked positions appear over the slider/your cursor and the video continues running normally.
   With the help of the preview pictures you find the right position and release the left mouse button.
   After releasing the mouse button the player begins playing at the desired position.

LOL. CloudStalker thinks that's a great idea. herojoker wants something like this then: Thumbnail Preview From Seek Bar
If you read further, a developer says that it's difficult to implement.

It isn't that hard to implement it, but there are certain issues with it. Like streams where we can't seek at all or seeking is problematic from multiple locations (like DVD) or HD streams. Decoding multiple HD images at once isn't possible with many current computers and trying to do that would kill the playback performance completely. Also I+P+B frame issues would hurt this because on worst case scenario if you roll backwards without cache you would have to decode something like 100 frames, then 99 frames etc. (assuming this case that key-frame distance is 100, it can be much more) and caching isn't possible because of memory limitations (generating and storing 100 1080p RAW frames to RAM in under 1 second isn't possible).

hi,

I wonder if we could incorporate the preview miniatures (just like 100 frames for each files) at the beginning of the file or the stream, as some sort of optional metadata (precomputed during the encoding). That way the new files would allow the navbar miniatures.

People have been asking for this for 13 years, according to various Google results, so I wouldn't hold my breath. However, if you're looking for a lightweight player that does this (or if the VLC developer is looking for inspiration on how), MPC-BE handles it fine.

I wonder if we could incorporate the preview miniatures (just like 100 frames for each files) at the beginning of the file or the stream, as some sort of optional metadata (precomputed during the encoding). That way the new files would allow the navbar miniatures.

In theory, this would be possible if somebody made a "standard" extension to embed the previews in MKV or MP4. Realistically however, none of the existing recorded videos would support it, and users would end up confused why it only rarely works.