Hacker News new | ask | show | jobs
by angry_octet 3606 days ago
The traffic pattern would be more specific to the playback device than the content. There might be more spread in duration, but even so, television networks like shows to go for specific times for ease of programming. As for encoding rates, it is quite possible they use CBR. Even if they use VBR they may choose different playout sources depending on the consuming devices and network conditions.

On the whole I doubt you would have a high probability of identifying any specific show. Even if you are able to cull 75% of the possibilities (i.e. 4 bits of entropy) that still leaves lots of shows (total ~1000 tv series and ~5000 movies by one source), plus all the noise of people pausing/switching, skipping credits, etc.
1 comments
repsilat 3606 days ago
How big is a show, sent compressed? A gigabyte an episode? I guess the range is more relevant, say plus or minus ten megs to be conservative. I don't know how big packets are, maybe 4k is too small? 10M/4k=2.5k, not bad, but not great if you want to avoid birthday collisions, you'd only get maybe 60 uniques if they're uniformly distributed.

CBR does kill it, though, and "uniformly distributed" is too big an ask.

Off topic, but an interesting thought: you know the HBO intro? With the static? That static is the hardest thing in the world to compress, and also the thing that viewers care the least about having compressed accurately. That's weird, I wonder how true it is across the board -- certainly artifacts can be jarring in flat shaded cartoons...

link
angry_octet 3605 days ago
900MB for 720p for an episode of TV drama seems typical, but I haven't run wireshark on my Netflix yet.

For DSL typical packet MTU is 1400-something. Why do you ask? It doesn't really matter because the upper level proto is oblivious. You can just use b/s instead of packets/s if you want to compare bitrates.

There are special encoding modes in 264/265 for handling animation. I'm not aware if there being modes for the intro except that it is monochromatic.

link
repsilat 3605 days ago
> For DSL typical packet MTU is 1400-something. Why do you ask?

I was wondering how finely you can get the total filesize if it's encrypted. Can you just count fixed size packets, or can you figure the length down to the byte? Makes a big difference if you're trying using that to fingerprint the shows.

link
angry_octet 3601 days ago
You can reassemble the https stream and get the exact length. Unless they do something weird like multiplexing, or change the playout rate, or the user pauses, it should be exact.
link