An ffmpeg and SDL Tutorial 08

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:

• Let's face it, this player sucks. The version of ffplay.c it is based on is totally outdated, and this tutorial needs a major rehaul as a result. If you want to move on to more serious projects using ffmpeg libraries, I implore you to check out the most recent version of ffplay.c as your next task.
• 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.
• 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.

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.

UPDATE It has been a long time since I updated this, and the world of video software has gotten a lot more mature. This tutorial has only required simple API updates; very little has actually changed in terms of the basic concepts. Most of those updates have actually simplified the code. However, while I have gone through and updated the code here, ffplay still totally outperforms this toy player. Let's be frank, it's pretty unusable as an actual movie player. So if you or your future self wants to improve this tutorial, go into ffplay and find out what we're missing. My guess is it's mostly taking advantage of video hardware, but maybe I'm missing some obvious things. It's possible ffplay might have drastically changed some things; I haven't looked yet.

But I'm very proud that it has still helped a lot of people out over the years, even if you had to go get code elsewhere. My absolute gratitude to chelyaev who did the work in replacing all the functions that were deprecated since I wrote this 8 (!) years ago.

Well, I hope this tutorial was instructive and fun. If you have any suggestions, bugs, complaints, accolades, etc., about this tutorial, please email me at dranger at gmail dot com. Please do not ask me for help in your other ffmpeg projects. I get way too many of those emails.

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

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Function Reference
Data Reference

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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.