Why add last pieces to the preparePieces list?

[se-bastiaan]

Why add last pieces to the preparePieces list?

[abbasshah17]

Thanks a lot.

[se-bastiaan]

which hints at video metadata sometimes being present at the end of the file.

That's exactly the reason.

[abbasshah17]

Then how do you make sure that the required information is completely downloaded, I'm talking in terms of size, how do you make sure you've downloaded the all the required pieces, containing metadata info.

In case we are downloading them blindly, is there a way to know firsthand which pieces should be downloaded? So that we only download the required pieces.

Also I realize it is out of the scope for this question, but can you also provide a reference where I can further look into different video types which describes the end-of-file-meta-data behavior.

[se-bastiaan]

It's a bit of a guess. Most of the metadata (container information, like MP4 of MKV) should fit in the first and last few pieces because the majority of the file is just video. I built this mostly based on trial-and-error and looking at the video player implementations iirc. If you open a mp4 video in a webbrowser for example you'll see in the network inspector that it specifically requests the last part of the file as well. It probably depends on the video player that is used, which for me was mostly a LibVLC based client and actually just Chrome via some HTTP server (and eventually TorrentStreamServer) to make sure that the videos could be played on Chromecast-like devices.

I don't remember looking up the specifications of video formats, but you should be able to find them to see how the container formats actually work. Matroska (mkv) is here for example: https://matroska.org/technical/order/index.html