felixjones / libagmv

An open-source full-motion video codec optimized for real-time playback on low-end graphical devices.

libagmv - Adaptive Graphics Motion Video

An open-source full-motion video codec optimized for real-time playback on low-end graphical devices.

About

AGMV is an indexed colored, block-based full-motion video codec that utilizes classic color quantization, progressive interpolated motion compensation, lz77/lzss data compression, a routine 2:1 audio compression algorithm, and various other old-school video compression techniques inspired from the classics such as Smacker video and Quake 2's Cinematics video formats to achieve real-time video playback on low-end graphical devices favoring decoding speed over aggressive compression routines to ensure that even a CPU clocked at 16.78MHz like the Nintendo Game Boy Advance can decode individual frames in real time.

Why use AGMV? AGMV serves four purposes:

* It maintains blazing fast decoding speed to even where low-end hardware such as the GBA can use it for real-time video playback.
* It uses the RGB color space, the native color space of most graphical devices, to avoid any intermediary color conversion step so that a decoded frame can be immediately blitted to the screen. 
* At the cost of some visual quality, it can even rival Smacker video, MJPEG, and Cinepak compression rates while being virtually 4x easier to decode.

GBA Video Demo

output.mp4

Video Player Demo

agmvp_out.mp4

Example Programs

Simple Video Encoding

#include <stdio.h>
#include <agmv.h>
#include <agidl.h>

int main(){
	AGMV* agmv = CreateAGMV(212,320,240,24); /* (Number of Frames, Width, Height, Frames per Second) */
	AGMV_WavToAudioTrack("example.wav",agmv);
	AGMV_EncodeAGMV(agmv,"example.agmv","example_directory","agmv_base_name",AGMV_IMG_BMP,1,212,320,240,24,AGMV_OPT_III,AGMV_LOW_QUALITY,AGMV_LZSS_COMPRESSION);
	
	return 0;
}

Simple GBA Video Encoding

#include <stdio.h>
#include <agmv.h>

int main(){
	u32 total_num_frames = 210;
 	/*GENERATES A C HEADER FILE CALLED SOUND.H -> USE RAW SIGNED 8-BIT PCM WHEN CALLING THIS FUNCTION*/
	AGMV_ExportRaw8PCM("example.raw",total_num_frames/2.0f); /*IF AGMV_OPT_GBA_I OR AGMV_OPT_GBA_II DIVIDE BY 2, IF AGMV_OPT_GBA_III MULTIPLY BY 0.75*/
 	/* GENERATES A C HEADER FILE CONTAINING AGMV VIDEO*/
	AGMV_EncodeVideo("example.agmv","example_directory","agmv_base_name",AGMV_IMG_BMP,1,total_num_frames,320,240,24,AGMV_OPT_GBA_I,AGMV_LOW_QUALITY,AGMV_LZSS_COMPRESSION);
	
	return 0;
}

Simple Video Decoding

#include <stdio.h>
#include <agmv.h>
#include <agidl.h>

int main(){

	AGMV_DecodeAGMV("example.agmv",AGMV_IMG_BMP,AGMV_AUDIO_WAV);
	
	return 0;
}

Simple Audio Decoding

#include <stdio.h>
#include <agmv.h>
#include <agidl.h>

int main(){

	AGMV_DecodeAudio("example.agmv",AGMV_AUDIO_WAV);
	
	return 0;
}

Commands in FFMPEG to Extract Frames

1. Convert frame rate of video to 24 frames per second(use 16 if size is really important) ffmpeg -i example.mp4 -filter:v fps=fps=24 new_example.mp4
2. Extract audio from new video ffmpeg -i new_example.mp4 example.wav
3. Extract image frames from video ffmpeg -i new_example.mp4 agmv_frame_%d.bmp
4. In audacity, drag and drop example.wav
5. Click on Tracks on the top bar and select Mix Stereo Down to Mono if the audio is not already mono.
6. Now, still on Tracks, select resample, and choose 16,000.
7. Next, click on File at the top, Export, then Export Audio.
8. In Save Type, select other compressed files
9. In Header, select Raw(header-less)
10. In encoding, select Signed 8-bit PCM
11. Now, click save