FFmpeg README

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

This fork of FFmpeg has a single addition: handling unexpected stream terminations.

The file libavformat/utils.c has the routine av_read_frame() modified to call the library client's I/O Interrupt Callback within the stream packet reading forever loop, inside av_read_frame(). By installing one's own I/O Interrupt Callback an application can monitor IP and USB streams for the unexpected event of stream loss. Unexpected stream termination is identified by a call to av_read_frame() simply taking too long. When calling av_read_frame() with an installed I/O Interrupt Callback, every loop attempt to read from the stream also receives an I/O Interrupt Callback. Within the I/O Interrupt Callback the library client simply checks the clock - if this read is taking too long, return true to signal a stream's unexpected termination.

The I/O Interrupt Callback looks like:

int interrupt_callback( void *context );

And it is installed by setting pointers on the AVFormatContext:

 AVFormatContext* p_format_context = avformat_alloc_context();
 p_format_context->interrupt_callback.callback = FFVideo_FrameMgr::interrupt_callback;
 p_format_context->interrupt_callback.opaque = mp_frameMgr;

Then when calling av_read_frame() your I/O Interrupt Callback is repeatedly called. Just check the time then for being too long, and return true if too long.

This is the only modification to FFmpeg in this fork.

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.