smallpond

commit 1cb07c131753e1343d45196407e661ef86fd22be
parent 482c0f4585e67389cd643df5de640274ee195c96
Author: Nihal Jere <nihal@nihaljere.xyz>
Date:   Mon, 24 Oct 2022 10:42:28 -0500

poorly drawn video frame

Diffstat:
M
Makefile
 | 
3
++-
M
main.c
 | 
137
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----

2 files changed, 132 insertions(+), 8 deletions(-)
diff --git a/Makefile b/Makefile
@@ -1,5 +1,6 @@
 smallpond: main.c
-	gcc -o smallpond main.c $(shell pkg-config --cflags --libs lua) $(shell pkg-config --cflags --libs freetype2) $(shell pkg-config --cflags --libs cairo)
+	gcc -o smallpond main.c $(shell pkg-config --cflags --libs lua) $(shell pkg-config --cflags --libs freetype2) $(shell pkg-config --cflags --libs cairo) $(shell pkg-config --cflags --libs libavcodec) $(shell pkg-config --cflags --libs libavutil)
+
 
 clean:
 	rm -f smallpond
diff --git a/main.c b/main.c
@@ -1,3 +1,4 @@
+#include <stdint.h>
 #include <stdio.h>
 
 #include <ft2build.h>
@@ -7,6 +8,9 @@
 #include <cairo-pdf.h>
 #include <cairo.h>
 
+#include <libavcodec/avcodec.h>
+#include <libavutil/frame.h>
+
 #include <lua.h>
 #include <lauxlib.h>
 #include <lualib.h>
@@ -98,12 +102,6 @@ create_surface(lua_State *L)
 	double width = lua_tonumber(L, -2);
 	double height = lua_tonumber(L, -1);
 
-	cairo_destroy(cr);
-	cairo_surface_destroy(surface);
-
-	surface = cairo_pdf_surface_create("out.pdf", width, height);
-	cr = cairo_create(surface);
-
 	cairo_set_font_face(cr, cface);
 	cairo_set_font_size(cr, 32.0);
 
@@ -111,6 +109,31 @@ create_surface(lua_State *L)
 }
 
 int
+putframe(AVCodecContext *ctx, AVFrame *frame, AVPacket *pkt, FILE *out)
+{
+	int ret;
+
+	ret = avcodec_send_frame(ctx, frame);
+	if (ret < 0) {
+		fprintf(stderr, "error sending frame to encoder\n");
+		exit(1);
+	}
+
+	while (ret >= 0) {
+		ret = avcodec_receive_packet(ctx, pkt);
+		if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
+			return 0;
+		else if (ret < 0) {
+			fprintf(stderr, "error encoding audio frame\n");
+			exit(1);
+		}
+
+		fwrite(pkt->data, 1, pkt->size, out);
+		av_packet_unref(pkt);
+	}
+}
+
+int
 main(int argc, char *argv[])
 {
 	lua_State *L = luaL_newstate();
@@ -146,16 +169,116 @@ main(int argc, char *argv[])
 		return 1;
 	}
 
-	surface = cairo_image_surface_create (CAIRO_FORMAT_A8, 1, 1);
+	FILE *output = fopen("out.h264", "wb");
+	if (!output) {
+		fprintf(stderr, "couldn't open output\n");
+		return 1;
+	}
+
+	AVPacket *pkt = av_packet_alloc();
+	if (!pkt) {
+		fprintf(stderr, "couldn't allocate packet!\n");
+		return 1;
+	}
+
+	AVFrame *frame = av_frame_alloc();
+	if (!frame) {
+		fprintf(stderr, "couldn't allocate frame!\n");
+		return 1;
+	}
+
+	const AVCodec *codec = avcodec_find_encoder_by_name("libx264rgb");
+	if (!codec) {
+		fprintf(stderr, "couldn't find h264 codec!\n");
+		return 1;
+	}
+
+	AVCodecContext *c = avcodec_alloc_context3(codec);
+	if (!c) {
+		fprintf(stderr, "couldn't alloc AVCodec context!\n");
+		return 1;
+	}
+
+	// suggested bitrates: https://www.videoproc.com/media-converter/bitrate-setting-for-h264.htm
+	// 720 x 480: 1800 kbps
+	// 1280 x 720: 3500 kbps
+	// 1920 x 1080: 8500 kbps
+	c->bit_rate = 1800*1000;
+	c->width = 720;
+	c->height = 480;
+	c->time_base.num = 1;
+	c->time_base.den = 30;
+	c->framerate.num = 30;
+	c->framerate.den = 1;
+	c->pix_fmt = AV_PIX_FMT_RGB24;
+	c->gop_size = 30*3;
+	AVDictionary *opts = NULL;
+
+	frame->format = c->pix_fmt;
+	frame->width = c->width;
+	frame->height = c->height;
+
+	if (avcodec_open2(c, codec, &opts) < 0) {
+		fprintf(stderr, "failed to open codec\n");
+		return 1;
+	}
+
+	if (av_frame_get_buffer(frame, 0) < 0) {
+		fprintf(stderr, "couldn't allocate frame data\n");
+		return 1;
+	}
+
+	surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24, 720, 480);
 	cr = cairo_create(surface);
 
 	cairo_set_font_face(cr, cface);
 	cairo_set_font_size(cr, 32.0);
+	if (av_frame_make_writable(frame) < 0) {
+		fprintf(stderr, "couldn't make frame writeable\n");
+		return 1;
+	}
+	/* fill with white */
+	cairo_set_source_rgb(cr, 1.0, 1.0, 1.0);
+	cairo_rectangle(cr, 0, 0, 720, 480);
+	cairo_fill(cr);
 	if (luaL_dofile(L, "smallpond.lua")) {
 		fprintf(stderr, "lua error: %s\n", lua_tostring(L, -1));
 		return 1;
 	}
 
+	unsigned char *image_data = cairo_image_surface_get_data(surface);
+
+	printf("avframe line size: %d\n", frame->linesize[0]);
+	for (int i = 0; i < 30; i++) {
+		if (av_frame_make_writable(frame) < 0) {
+			fprintf(stderr, "couldn't make frame writeable\n");
+			return 1;
+		}
+
+		for (int x = 0; x < 720; x++) {
+			for (int y = 0; y < 480; y++) {
+				int srcoffset = cairo_format_stride_for_width(CAIRO_FORMAT_RGB24, 720) * y + x;
+				uint32_t val = ((uint32_t *)image_data)[srcoffset];
+				// we are assuming RGB24 here
+				int offset = y * frame->linesize[0] + 3*x;
+				frame->data[0][offset + 2] = (val >> 16) & 0xFF;
+				frame->data[0][offset + 1] = (val >> 8) & 0xFF;
+				frame->data[0][offset] = val & 0xFF;
+			}
+		}
+
+		fflush(stdout);
+		frame->pts = i;
+		putframe(c, frame, pkt, output);
+	}
+
+	putframe(c, NULL, pkt, output);
+	fclose(output);
+
+	avcodec_free_context(&c);
+	av_frame_free(&frame);
+	av_packet_free(&pkt);
+
 	cairo_destroy(cr);
 	cairo_surface_destroy(surface);
 	lua_close(L);