end.java

ffmpeg开发指南

## An ffmpeg and SDL Tutorial

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### What now?

So we have a working player, but it's certainly not as nice as it could be. We
did a lot of handwaving, and there are a lot of other features we could add: 

  * Error handling. The error handling in our code is abysmal, and could be
handled a lot better.
  * Pausing. We can't pause the movie, which is admittedly a useful feature.
We can do this by making use of an internal paused variable in our big struct
that we set when the user pauses. Then our audio, video, and decode threads
check for it so they don't output anything. We also use av_read_play for
network support. It's pretty simple to explain, but it's not obvious to figure
out for yourself, **so consider this homework** if you want to try more. For
hints, check out ffplay.c.
  * Support for video hardware. For a sample of setting this up, check out the
Frame Grabbing section in Martin's old tutorial.
  * Seeking by bytes. If you calculate the seek position by bytes instead of
seconds, it is more accurate on video files that have discontiguous
timestamps, like VOB files.
  * Frame dropping. If the video falls too far behind, we should drop the next
frame instead of setting a short refresh.
  * Network support. This video player can't play network streaming video.
  * Support for raw video like YUV files. There are some options we have to
set if our player is to support raw video like YUV files, as we cannot guess
the size or time_base.
  * Fullscreen
  * Various options, e.g. different pic formats; see ffplay.c for all the
command line switches.
  * Other hand-wavy things; for example, the audio buffer in our struct should
be declared aligned.

If you want to know more about ffmpeg, we've only covered a portion of it. The
next step would be to study how to _encode_ multimedia. A good place to start
would be the output_example.c file in the ffmpeg distribution. I may write
another tutorial on that, but I might not get around to it. 

Well, I hope this tutorial was instructive and fun. If you have any
suggestions, bugs, complaints, accolades, etc., please email me at dranger at
gmail dot com. 

Links:  
ffmpeg home page  
Martin Bohme's original tutorial  
libSDL  
SDL Documentation

* * *

Function Reference  
Data Reference

email:
dranger at gmail dot com
Back to dranger.com

This work is licensed under the Creative Commons Attribution-Share Alike 2.5
License. To view a copy of this license, visit
http://creativecommons.org/licenses/by-sa/2.5/ or send a letter to Creative
Commons, 543 Howard Street, 5th Floor, San Francisco, California, 94105, USA. 
 
  
Code examples are based off of FFplay, Copyright (c) 2003 Fabrice Bellard, and
a tutorial by Martin Bohme.