Currently Watching Alien 1979

[Smucky]

Well not actually watching yet. The bootleg copy I got is in 5.1 surround sound, which I don't have. Wasn't too thrilled with the mix so a bit of ffmpeg foo to down mix to 2 channel stereo, export to wav, import to audacity and run through a compressor and normalize. Now much better, no more unhearable whispering followed by deafening sound effects

Was just about to reencode the audio and splice it back into the video file, but figured since I was encoding the audio, maybe I could play around with reencoding the video. I've been using the SVT-AV1 encoder with ffmpeg. The codec timeline is more or less h264 -> h265 (hvec) -> VP8 -> VP9 -> AV1 so we are on the bleeding edge! Each one claiming 20% smaller size than their predecessor. I've been using AV1 for probably a year now, but mostly for cartoons and kid crap, nothing that I really cared about.

Anyway, as a quick test to get going, I cropped the first 10 minutes of Alien into a separate file, and did a quick encode with

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ffmpeg  -i Alien.1979_short.mkv   -c:v libsvtav1 -crf 29 -preset 8 -c:a libopus -ab 96K  test.mkv

And that averaged out at ~500kbs. So a rough estimate would mean the original 7GB file would end up being ~400MB. An almost 2 hour movie, in 1080p, with heavy film grain and it would only take up 400MB? Sounds too good to be true. I went ahead and got the whole movie encoding, which only took 40 minutes. Came out to 660MB.

Typically after encoding at a questionable rate, I'd skip around in the video looking for high action scenes and make sure they are still clean looking. But I haven't seen this movie since I was like 4 which is nearly 40 years ago. So I didn't want to ruin it by actually watching parts of it. A bit more foo with ffmpeg

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ffmpeg -i Alien.1979.mkv   -vf "showinfo" -f null - 2>&1 |   grep -oP 'pts_time:\K[0-9.]+|stdev:\[\K[0-9.]+'

Or more or less: print out all the frames with a time stamp (pts_time) and the deviation (stdev) of the previous scene and then you can sort by deviation values. There seemed to be quite a bit of deviations scene to scene between the 1:40:00 to 1:45:00 marks. So I ripped out some screen shots from that range.

I was hoping I wouldn't see any spoilers, but these are just images, so should be fine. But the first thing I saw was Ripley with a flamethrower.

Man had a flood of memories come over me. I could now remember watching the movie, but being too young to really comprehend an "alien" or even fear itself. I remember being bored with it. But then I remember some chick with a flame thrower lighting stuff on fire and roasting alien eggs, etc. And I remember being mesmerized by that. That must have been the start of my long term love affair with fire

But anyway, back to comparisons...

The original file weighting in at 7GB in 265 hvec:

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And with -c:v libsvtav1 -crf 29 -preset 8 weighting in at 660MB:

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And after some experiments,
I ended up going with -c:v libsvtav1 -crf 25 -preset 8 weighting in at 870MB:

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Spent probably 3 hours comparing screenshots and making this post

Anyway, kind of impressive. Maybe I should have grabbed the 4k version instead