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Old 4th October 2008, 00:13   #1  |  Link
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excessive matroska overhead?

I'm encoding a 120 minute DVD to x264 video and vorbis audio, with Handbrake. I used a video bitrate of 1800 kbps and vorbis at 160 kbps (I know vorbis uses a quality setting, but handbrake asks for a bitrate so I'm assuming it's equating to quality level 5 or such when it actually calls vorbis). I'm muxing the video and one audio stream and end up with a 1.8GB file.
I was curious how large the separate streams were so I used mkvmerge to dump each single stream to it's own container. I ended up with:

video.mkv - 1.4GB
audio1.mkv - 627MB
video_audio_muxed.mkv - 1.8GB

what?! the final muxed file with both video and audio ends up at 1.8GB! So I'm thinking to myself, this has got to be a bug, there's no way matroska should be taking roughly 3.4GB overhead! I took the separate streams and remuxed to a combined file and still end up with 1.8GB!

As another test, I extracted just 1 chapter from the same movie, and ended up with:

video.mkv - 45.8MB
audio.mkv - 19.9MB
video_audio_muxed.mkv - 65.6MB

...forgiving the MB rounding my file explorer is making, this seems right on, and just what I would expect, but I have no idea where things are going wrong the full-length mux.

Has anyone seen this type of problem before or have any thoughts or insights? I think perhaps Handbrake is messing up the matroska container somehow, but I just don't know enough to discount any other possible causes as well.
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Old 4th October 2008, 01:31   #2  |  Link
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Huh? 1.4 + 0.627 = 2.0 gigabytes so your file is actually smaller by 200 megabytes! Also, Windows Explorer shows the size of a file in bytes.
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Old 4th October 2008, 08:08   #3  |  Link
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id10t addition error on my part

LOL! You're absolutely right! The math works just fine and the resulting mux'd file size is quite reasonable. For some strange reason In my head I was carrying the decimal over one place to the left on the MB when adding them, and didn't even realize it. blaming it on a late night! Thanks for pointing out the extremely obvious! crazy. Well for an otherwise worthless thread I hope someone gets a good laugh out of this
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large, matroska, overhead

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