SPARCHER.TechBlog

2017-12-25

HOWTO: optimize MP4 video for fast loading with FFmpeg

MP4 video loading can be accelerated (e. g., allowing playback of partially downloaded videos for end users) by moving the metadata (the "moov atom") to the beginning of the file. And that's a lossless procedure (no video, audio or subtitle data gets lost; may alter some metadata though)!

Can be performed very fast and easily with the qt-faststart utility (targeted primarily at Apple QuickTime MOV files, but should work for most MP4 base media files too); you can find that utility in your favorite FFmpeg distribution.
```
$ qt-faststart in01.mov out01.mov
$ qt-faststart in02.mp4 out02.mp4
```
More thorough (but a little bit slower) method involves the universal ffmpeg program to remux the original video:
```
$ ffmpeg -i in10.mp4 -codec copy -movflags faststart out10.mp4
```

Reference:

FFmpeg Formats Documentation

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Last updated: 2018-03-01

2017-12-23

Websites: VirusTotal

VirusTotal is a great online virus scanner, a Google subsidiary.
You can either scan a local file, or submit a remote URL; you can also search the database by file hash (SHA256, SHA1, MD5 etc.).
There's also a rating system for registered users.
Warning: all files you try to scan using this online service are actually get uploaded onto the remote server (or "cloud") for scanning, and subsequently can be shared with antivirus software developers in the future, so you should avoid scanning any confidential documents with this service ;-)
By uploading new malware, we can somehow improve the contemporary anti-virus solutions!

Links:

home page,
- currently, loading some kind of Web-2.0-styled uploader;
~~rather old-style home page~~ (unfortunately, apparently discontinued).

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Last updated: 2019-04-24

2017-04-21

HOWTO: decompress WOFF2 fonts

Once upon a time you can stumble upon a WOFF2 font file; it's in WOFF 2.0 format, an improved version of Web Open Font Format.
And it's quite easy to unpack such compressed files to get the usual TTF (and maybe OTF) fonts -- just use the woff2_decompress utility from the woff2 Google project on GitHub:

$ woff2_decompress myfont.woff2

(please note: you need to compile that project before use, and it's much easier to do in GNU/Linux and other Unix-like environments, than in MS Windows).

2017-04-01

Websites: BugMeNot (shared logins)

Have you ever visited an ugly site requiring registration to access some ordinary info? Tired of countless one-time registrations?
BugMeNot can help: it's the site where you and other ordinary users can share their useless login info (disposable email addresses are usually used for such registrations) for a variety of useless sites :-)

Disclaimer: no warranties, only for educational use, some sites get blocked from the site, and please don't abuse it etc. ;-)

External links:

2017-03-30

HOWTO: base64 manipulations in Linux

Do you want to decode some base64-encoded strings (or any other data), or convert some binary file to text (in base64)?
It's quite easy to do that in Debian GNU/Linux: base64 utility is a part of coreutils package (that package has a "required" priority, i. e., it's an essential package for the system to work).

When you finish typing your strings, don't forget to press <Enter> followed by <Ctrl> + <D> (or <Ctrl> + <D> twice, if you don't like newlines).

$ base64
Hello, world!
SGVsbG8sIHdvcmxkIQo=
$ 
$ base64 -d
SGVsbG8sIHdvcmxkIQo=
Hello, world!

But it may be safer to use file input-output, e. g.:

$ base64 -d in.txt > out.dat

References: