Even though you can already generate AVI files, this library has not reached a final version yet and is still a work in progress. You've been warned... ;)
libgwavi
is a fork of libkohn-avi
. It is a tiny C library aimed at creating
AVI files.
Original credits go to Michael Kohn, who released his library under the LGPL license. He, however, allowed me to release my forked version under the less restrictive 3-clause BSD license so... Thanks to him!
Anyway, why the fork you might ask? I used it in an application that needed the
library to be reliable. So here is what has already changed from libkohn-avi
:
added library documentation
removed dead code
improved error checking
added unit tests
This library has no dependencies, you only need the standard C library.
To generate libgwavi.so
, just type the following from the root's directory:
make
To generate the documentation of the library functions, type the following:
make doc
The code includes a demo application that uses libgwavi
. You can build it
using this command:
make examples
For a complete example, have a look at the demo application in the examples folder.
If you are in a hurry, here is a small explanation on how to use it.
First, you need to include the header file.
#include "gwavi.h"
There is basically four main function that you will need to use:
gwavi_open()
gwavi_add_frame()
gwavi_add_audio()
gwavi_close()
Please, note that error checking has been voluntarily omitted in the examples below for the sake of the clarification.
So first, you should declare a gwavi_t
structure and initialize it. You can
optionally declare a gwavi_audio_t
structure if you need to add an audio
channel to your AVI file.
To declare a gwavi_audio_t
, firstly, you can see it's a structure constructed of channels
, bits
and samples_per_second
.
To get these info, you can save the audio first, and then, open it using VLC media player.
After that, Tools -> Codec Infomation -> Codec
channels
, if VLC says "Mono", write 1
; if it says "Stereo", write 2
.bits
, write as same as "Bits per sample".samples_per_second
, write as same as "Sample rate".By default, this program accepts audios whose codec in VLC shows araw
only. For example, whose file extension is wav
.
Note! You may need to declare this BEFORE running gwavi_open()
.
For example:
struct gwavi_t *gwavi;
struct gwavi_audio_t audio = {
.channels = 2,
.bits = 16,
.samples_per_second = 44100
};
gwavi = gwavi_open("foo.avi",
1920,
1080,
"MJPG",
30,
&audio);
Note that the audio channel is optional and that you can pass NULL
as the last
argument of gwavi_open()
if you don't need it.
Then you add your video frames:
gwavi_add_frame(gwavi, buffer, buffer_length);
You can also add audio with gwavi_add_audio()
.
And at the end, you can close the output file and free the allocated memory by
calling the gwavi_close()
function.
gwavi_close(gwavi);
The library documentation can be generated with make doc
if you have
doxygen
installed. Otherwise, you can just visit
http://doc.gw-computing.net/libgwavi.