// tutorial02.c
// A pedagogical video player that will stream through every video frame as fast as it can.
//
// Code based on FFplay, Copyright (c) 2003 Fabrice Bellard,
// and a tutorial by Martin Bohme (boehme@inb.uni-luebeckREMOVETHIS.de)
// and another tutorial by Stephen Dranger (dranger at gmail dot com)
// Tested on Gentoo, CVS version 5/01/07 compiled with GCC 4.1.1
// Use
//
// gcc -o tutorial02 tutorial02.c -lavformat -lavcodec -lswscale -lz -lm `sdl-config --cflags --libs`
// to build (assuming libavformat and libavcodec and libswscale are correctly installed,
// and assuming you have sdl-config. Please refer to SDL docs for your installation.)
//
// Run using
// tutorial02 myvideofile.mpg
//
// to play the video stream on your screen.

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

#include <SDL/SDL.h>
#include <SDL/SDL_thread.h>

#ifdef __MINGW32__
#undef main /* Prevents SDL from overriding main() */
#endif

#include <stdio.h>

int main(int argc, char *argv[]) {
	AVFormatContext *pFormatCtx = NULL;
	int i, videoStream;
	AVCodecContext *pCodecCtx;
	AVCodec *pCodec;
	AVFrame *pFrame;
	AVPacket packet;
	struct SwsContext * pSwsCtx;
	int frameFinished;

	SDL_Overlay *bmp;
	SDL_Surface *screen;
	SDL_Rect rect;
	SDL_Event event;

	if (argc < 2) {
		fprintf(stderr, "Usage: test <file>\n");
		exit(1);
	}
	// Register all formats and codecs
	av_register_all();

	if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
		fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
		exit(1);
	}

	// Open video file
	if (avformat_open_input(&pFormatCtx, argv[1], NULL, NULL) != 0)
		return -1; // Couldn't open file

	// Retrieve stream information
	if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
		return -1; // Couldn't find stream information

	// Dump information about file onto standard error
	av_dump_format(pFormatCtx, 0, argv[1], 0);

	// Find the first video stream
	videoStream = -1;
	for (i = 0; i < pFormatCtx->nb_streams; i++)
		if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
			videoStream = i;
			break;
		}
	if (videoStream == -1)
		return -1; // Didn't find a video stream

	// Get a pointer to the codec context for the video stream
	pCodecCtx = pFormatCtx->streams[videoStream]->codec;

	// Find the decoder for the video stream
	pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
	if (pCodec == NULL) {
		fprintf(stderr, "Unsupported codec!\n");
		return -1; // Codec not found
	}

	// Open codec
	if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
		return -1; // Could not open codec

	// Allocate video frame
	pFrame = avcodec_alloc_frame();

	pSwsCtx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
			pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
			PIX_FMT_YUV420P, SWS_FAST_BILINEAR, NULL, NULL, NULL);

	if (pSwsCtx == NULL) {
		fprintf(stderr, "Cannot initialize the sws context\n");
		return -1;
	}

	// Make a screen to put our video
#ifndef __DARWIN__
	screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);
#else
	screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);
#endif
	if (!screen) {
		fprintf(stderr, "SDL: could not set video mode - exiting\n");
		exit(1);
	}

	// Allocate a place to put our YUV image on that screen
	bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,
			SDL_YV12_OVERLAY, screen);

	// Read frames and save first five frames to disk
	i = 0;
	while (av_read_frame(pFormatCtx, &packet) >= 0) {
		// Is this a packet from the video stream?
		if (packet.stream_index == videoStream) {
			// Decode video frame
			avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);

			// Did we get a video frame?
			if (frameFinished) {
				SDL_LockYUVOverlay(bmp);

				AVPicture pict;
				pict.data[0] = bmp->pixels[0];
				pict.data[1] = bmp->pixels[2];
				pict.data[2] = bmp->pixels[1];

				pict.linesize[0] = bmp->pitches[0];
				pict.linesize[1] = bmp->pitches[2];
				pict.linesize[2] = bmp->pitches[1];

				// Convert the image into YUV format that SDL uses
				sws_scale(pSwsCtx, (const uint8_t * const *) pFrame->data,
						pFrame->linesize, 0, pCodecCtx->height, pict.data,
						pict.linesize);

				SDL_UnlockYUVOverlay(bmp);

				rect.x = 0;
				rect.y = 0;
				rect.w = pCodecCtx->width;
				rect.h = pCodecCtx->height;
				SDL_DisplayYUVOverlay(bmp, &rect);

			}
		}

		// Free the packet that was allocated by av_read_frame
		av_free_packet(&packet);
		SDL_PollEvent(&event);
		switch (event.type) {
		case SDL_QUIT:
			SDL_Quit();
			exit(0);
			break;
		default:
			break;
		}

	}

	// Free the YUV frame
	av_free(pFrame);

	// Close the codec
	avcodec_close(pCodecCtx);

	// Close the video file
	avformat_close_input(&pFormatCtx);

	return 0;
}