Is """moov atom""" — or whatever it's called in the case of .webm videos — at the top of WEBM video code, or at least: optimized, useful ?
After testing "MkClean (win32 v.0.8.7)" * on some video, to be played by a web page, I found no difference with the — same (of course) — video, but NOT-faststart-optimized.
* "MkClean" is a utility that's supposed to optimize .webm videos the same way (or about) .mp4 videos are optimized, by placing "moov atom" at the top of the code.
"MkClean" seems to work, though. Once open as plain text, the code contents is different than of the non optimized version of the same .webm file ; and the optimized file still works ;
so far so good. BUT: NOT optimized, it loads, starts playing and seeks just as fast (or slow, in case of a lousy connection), as the optimized test.
I followed the advice of https://rigor.com/blog/2016/02/optimizing-webm-video-for-faster-streaming-and-seeking (the information looked reliable to me / but I know nothing about .WEBM optimization...).
Reason of my question: with .mp4 videos, "moov atom at the top" is simply... crucial; needless to test a non optimized video: it'll just take "for ever" to start playing. OK;
now, WITH .WEBM, it's not so clear. Or... is it ? Or am I missing something?
Thanks (+ plz excuse my non native English)
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The WebM file structure is based on the Matroska media container, per WebM FAQ.
And FFmpeg does have an option for Matroska that's similar to 'faststart':matroska - options
This muxer supports the following options:
By default, this muxer writes the index for seeking (called cues in Matroska terms) at the end of the file, because it cannot know in advance how much space to leave for the index at the beginning of the file. However for some use cases – e.g. streaming where seeking is possible but slow – it is useful to put the index at the beginning of the file.
Thanks for the answer.
* Or in some cases only? And if so, when should I take care of it?
BTW, I tested using "Pazera WebM Converter 1.1 64-bit" (because it's easy ...). I guess it places the "cue" info. at bottom; + the interface has no "cue (faststart)" option anyway, neither mention whatsoever, about optimization (unless I missed it?)...
Last edited by bulgom; 18th Jul 2017 at 06:00.