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Jose Da Silva c31a7d07f6 avcodec/xbmenc: Allow for making UW images
I've run into some bugs where I was downloading a bunch of data and began
seeing weird hiccups. For example, javascript promises to allow you to push
some very long lines of data, but the hiccups I saw was with data larger
than 2k in length (windows) pushed out of a child process stdout piped into
the stdin of the calling parent program.
Soo much for smooth promises, this was broken and would run into similar
problems on a linux PC with 32k line limits.
The solution was to break the data into smaller chunks than 2k - and then
these data hiccups disappeared (windows PC).

It would be expected to be similar for linux PCs (32k I think) and other
OSes with different sizes.

If the ANSI required minimum needs to be 509 chars or larger (assuming
509+<CR>+<LF>+<0>=512), then 509 was chosen as the shortest worst-case
scenario) in this patch.
Most small pictures will go output looking pretty much the same data out
until you get to about 84bytes (672 pixels wide), where lines out begin to
be split. For example a UW 4K will exceed a 2k readln and a UW 10K picture
approaches an 8k readln

The purpose for this patch is to ensure that data remains below the
readline limits (of 509 chars), so that programs (like javascript) can push
data in large chunks without breaking into hiccups because the data length
is too long to be pushed cleanly in one go.
Subject: [PATCH 3/3] avcodec/xbmenc: Allow for making UW images

Worst-case ANSI must allow for 509 chars, while Windows allows for 2048
and Linux for 32K line length. This allows an OS with a small readline
access limitation to fetch very wide images (created from ffmpeg).
2021-01-28 15:50:37 +01:00
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FFmpeg README

FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.

Libraries

  • libavcodec provides implementation of a wider range of codecs.
  • libavformat implements streaming protocols, container formats and basic I/O access.
  • libavutil includes hashers, decompressors and miscellaneous utility functions.
  • libavfilter provides a mean to alter decoded Audio and Video through chain of filters.
  • libavdevice provides an abstraction to access capture and playback devices.
  • libswresample implements audio mixing and resampling routines.
  • libswscale implements color conversion and scaling routines.

Tools

  • ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
  • ffplay is a minimalistic multimedia player.
  • ffprobe is a simple analysis tool to inspect multimedia content.
  • Additional small tools such as aviocat, ismindex and qt-faststart.

Documentation

The offline documentation is available in the doc/ directory.

The online documentation is available in the main website and in the wiki.

Examples

Coding examples are available in the doc/examples directory.

License

FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.

Contributing

Patches should be submitted to the ffmpeg-devel mailing list using git format-patch or git send-email. Github pull requests should be avoided because they are not part of our review process and will be ignored.

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