Encode scan thumbnails into video

[mdinger]

Adding the little mouseover preview box to videos like youtube does is apparently impossible because it's computationally expensive to decode the thumbnails either in realtime or at file load. This seems like something the encoder could do (perhaps optionally) and then save into the video file. If this was available to decoders, it seems like they could enable this type of feature.

These thumbnails are really small. Doesn't seem like they'd take much space. Also could differentiate Daala from the others.

[tdaede]

This is more of a container level feature. However, a similar codec level could be added: very fast and low quality keyframe decoding - such as only decoding Haar DC coefficients.

For lower resolution videos, I'd expect a full keyframe decode to be fast enough that no special features are needed.

[mdinger]

That sounds good. Would it be fast enough to do realtime keyframe decode for a 4K video or bigger during regular decode (checking for all cases)? If so, I'll just modify the title/OP so it reflects that topic.