Document Windows FFmpeg build, etc.

Statically link FFmpeg on Windows. This requires building a slimmed-down
version of FFmpeg from source. The build process is documented in the
README.

Also add ffmpeg dependency to the nix flake.

README.md

@@ -64,6 +64,40 @@ First install MSYS2, and then open the MINGW64 shell and run the following comma
         mingw-w64-x86_64-libsndfile \
         mingw-w64-x86_64-glew
 
+To build with FFmpeg support, you must compile FFmpeg as a static library:
+
+    git clone https://github.com/FFmpeg/FFmpeg.git
+    cd FFmpeg
+    git checkout n6.0
+    ./configure --disable-everything \
+        --enable-decoder=mpegvideo \
+        --enable-decoder=mpeg1video \
+        --enable-decoder=mpeg2video \
+        --enable-decoder=mp2 \
+        --enable-parser=mpegaudio \
+        --enable-parser=mpegvideo \
+        --enable-demuxer=mpegps \
+        --enable-demuxer=mpegts \
+        --enable-demuxer=mpegtsraw \
+        --enable-demuxer=mpegvideo \
+        --enable-decoder=vc1 \
+        --enable-decoder=wmapro \
+        --enable-parser=vc1 \
+        --enable-hwaccel=vc1_d3d11va \
+        --enable-hwaccel=vc1_d3d11va2 \
+        --enable-hwaccel=vc1_dxva2 \
+        --enable-demuxer=asf \
+        --enable-protocol=file \
+        --enable-filter=scale \
+        --enable-static \
+        --disable-shared \
+        --extra-libs=-static \
+        --extra-cflags=--static
+    make
+    make install
+    cd ..
+    export PKG_CONFIG_PATH="/usr/local/lib/pkgconfig:$PKG_CONFIG_PATH"
+
 Then build the xsystem4 executable with meson,
 
     mkdir build

flake.nix

@@ -32,9 +32,11 @@
             libwebp
             libsndfile
             glew
-            readline
+            readline81
+            chibi
             flex
             bison
+            ffmpeg
           ];
         }
       );
@@ -60,9 +62,11 @@
               libwebp
               libsndfile
               glew
-              readline
+              readline81
+              chibi
               flex
               bison
+              ffmpeg
             ];
           };
         }

include/gfx/gfx.h

@@ -90,6 +90,7 @@ void gfx_init_texture_rgb(struct texture *t, int w, int h, SDL_Color color);
 void gfx_init_texture_with_pixels(struct texture *t, int w, int h, void *pixels);
 void gfx_init_texture_amap(struct texture *t, int w, int h, uint8_t *amap, SDL_Color color);
 void gfx_init_texture_rmap(struct texture *t, int w, int h, uint8_t *rmap);
+void gfx_update_texture_with_pixels(struct texture *t, void *pixels);
 void gfx_copy_main_surface(struct texture *dst);
 void gfx_delete_texture(struct texture *t);
 GLuint gfx_set_framebuffer(GLenum target, Texture *t, int x, int y, int w, int h);

meson.build

@@ -1,4 +1,5 @@
 project('system4', 'c',
+        meson_version: '>= 0.59',
         default_options : ['c_std=c11'])
 add_project_arguments('-D_DEFAULT_SOURCE', language : 'c')
 add_project_arguments('-DXSYS4_DATA_DIR="' + get_option('prefix') / get_option('datadir') / 'xsystem4"', language : 'c')
@@ -16,9 +17,14 @@ ffi = dependency('libffi', static : static_libs)
 tj = dependency('libturbojpeg', static : static_libs)
 webp = dependency('libwebp', static : static_libs)
 png = dependency('libpng', static : static_libs)
-cglm = dependency('cglm', fallback : ['cglm', 'cglm_dep'])
+cglm = dependency('cglm', version : '>=0.8.3', fallback : ['cglm', 'cglm_dep'])
 sndfile = dependency('sndfile', static : static_libs)
 
+avcodec = dependency('libavcodec', required: false, static : static_libs)
+avformat = dependency('libavformat', required: false, static : static_libs)
+avutil = dependency('libavutil', required: false, static : static_libs)
+swscale = dependency('libswscale', required: false, static : static_libs)
+
 gles = dependency('glesv2', version : '>=3', required: get_option('opengles'))
 if gles.found()
     gl_deps = [gles]

src/meson.build

@@ -20,7 +20,6 @@ xsystem4 = [version_h,
             'heap.c',
             'id_pool.c',
             'input.c',
-            'movie.c',
             'page.c',
             'resume.c',
             'savedata.c',
@@ -125,6 +124,13 @@ xsystem4 = [version_h,
 
 xsystem4_deps = [libm, zlib, sdl2, ft2, ffi, cglm, sndfile, libsys4_dep] + gl_deps
 
+if avcodec.found() and avformat.found() and avutil.found() and swscale.found()
+    xsystem4 += 'movie_ffmpeg.c'
+    xsystem4_deps += [avcodec, avformat, avutil, swscale]
+else
+    xsystem4 += 'movie_plmpeg.c'
+endif
+
 if get_option('debugger').allowed()
     add_project_arguments('-DDEBUGGER_ENABLED', language : 'c')
     xsystem4 += 'debug.c'

src/movie_ffmpeg.c

@@ -0,0 +1,401 @@
+/* Copyright (C) 2023 kichikuou <KichikuouChrome@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <SDL.h>
+#include <libavcodec/avcodec.h>
+#include <libavformat/avformat.h>
+#include <libavutil/fifo.h>
+#include <libavutil/imgutils.h>
+#include <libswscale/swscale.h>
+
+#include "system4.h"
+
+#include "gfx/gfx.h"
+#include "movie.h"
+#include "mixer.h"
+#include "sprite.h"
+#include "sts_mixer.h"
+#include "xsystem4.h"
+
+#define QUEUE_SIZE 10
+
+struct decoder {
+	AVStream *stream;
+	AVCodecContext *ctx;
+	AVFrame *frame;
+	AVFifoBuffer *queue;
+	bool finished;
+};
+
+struct movie_context {
+	AVFormatContext *format_ctx;
+	bool format_eof;
+	SDL_mutex *format_mutex;  // also protects video.queue and audio.queue
+
+	struct decoder video;
+	struct decoder audio;
+
+	struct texture temp_surface;
+
+	bool has_pending_video_frame;
+	struct SwsContext *sws_ctx;
+	AVFrame *sws_frame;
+	void *sws_buf;
+
+	sts_mixer_stream_t sts_stream;
+	int bytes_per_sample;
+	int voice;
+	int volume;
+
+	// Time keeping data. Written by audio handler and referenced by video
+	// handler (i.e. we sync the video to the audio).
+	double stream_time;  // in seconds
+	uint32_t wall_time_ms;
+	SDL_mutex *timer_mutex;
+};
+
+static void free_decoder(struct decoder *dec)
+{
+	if (dec->ctx)
+		avcodec_free_context(&dec->ctx);
+	if (dec->frame)
+		av_frame_free(&dec->frame);
+	if (dec->queue) {
+		while (av_fifo_size(dec->queue) > 0) {
+			AVPacket *packet;
+			av_fifo_generic_read(dec->queue, &packet, sizeof(AVPacket*), NULL);
+			av_packet_free(&packet);
+		}
+		av_fifo_freep(&dec->queue);
+	}
+}
+
+static bool init_decoder(struct decoder *dec, AVStream *stream)
+{
+	if (!stream)
+		return false;
+	dec->stream = stream;
+	const AVCodec *codec = avcodec_find_decoder(stream->codecpar->codec_id);
+	if (!codec)
+		return false;
+	dec->ctx = avcodec_alloc_context3(codec);
+	if (avcodec_parameters_to_context(dec->ctx, stream->codecpar) < 0)
+		return false;
+	if (avcodec_open2(dec->ctx, codec, NULL) != 0)
+		return false;
+	dec->frame = av_frame_alloc();
+	dec->queue = av_fifo_alloc(sizeof(AVPacket*) * QUEUE_SIZE);
+	return true;
+}
+
+static void read_packet(struct movie_context *mc)
+{
+	if (mc->format_eof)
+		return;
+
+	AVPacket *packet = av_packet_alloc();
+
+	while (av_read_frame(mc->format_ctx, packet) == 0) {
+		if (packet->stream_index == mc->video.stream->index) {
+			if (av_fifo_space(mc->video.queue) < (int)sizeof(AVPacket*))
+				av_fifo_grow(mc->video.queue, sizeof(AVPacket*) * QUEUE_SIZE);
+			av_fifo_generic_write(mc->video.queue, &packet, sizeof(AVPacket *), NULL);
+			return;
+		} else if (packet->stream_index == mc->audio.stream->index) {
+			if (av_fifo_space(mc->audio.queue) < (int)sizeof(AVPacket*))
+				av_fifo_grow(mc->audio.queue, sizeof(AVPacket*) * QUEUE_SIZE);
+			av_fifo_generic_write(mc->audio.queue, &packet, sizeof(AVPacket *), NULL);
+			return;
+		}
+		av_packet_unref(packet);
+	}
+	av_packet_free(&packet);
+	packet = NULL;
+	mc->format_eof = true;
+	av_fifo_generic_write(mc->video.queue, &packet, sizeof(AVPacket *), NULL);
+	av_fifo_generic_write(mc->audio.queue, &packet, sizeof(AVPacket *), NULL);
+}
+
+static void preload_packets(struct movie_context *mc)
+{
+	SDL_LockMutex(mc->format_mutex);
+	while (!mc->format_eof && (av_fifo_size(mc->video.queue) + av_fifo_size(mc->audio.queue) < (int)(QUEUE_SIZE * sizeof(AVPacket*))))
+		read_packet(mc);
+	SDL_UnlockMutex(mc->format_mutex);
+}
+
+static bool decode_frame(struct decoder *dec, struct movie_context *mc)
+{
+	int ret;
+	while ((ret = avcodec_receive_frame(dec->ctx, dec->frame)) == AVERROR(EAGAIN)) {
+		SDL_LockMutex(mc->format_mutex);
+		AVPacket *packet;
+		while (av_fifo_size(dec->queue) == 0)
+			read_packet(mc);
+		av_fifo_generic_read(dec->queue, &packet, sizeof(AVPacket*), NULL);
+		SDL_UnlockMutex(mc->format_mutex);
+
+		if ((ret = avcodec_send_packet(dec->ctx, packet)) != 0) {
+			WARNING("avcodec_send_packet failed: %d", ret);
+			return false;
+		}
+		av_packet_free(&packet);
+	}
+	if (ret == AVERROR_EOF)
+		dec->finished = true;
+	else if (ret)
+		WARNING("avcodec_receive_frame failed: %d", ret);
+	return ret == 0;
+}
+
+static int audio_callback(sts_mixer_sample_t *sample, void *data)
+{
+	struct movie_context *mc = data;
+	assert(sample == &mc->sts_stream.sample);
+
+	if (!decode_frame(&mc->audio, mc)) {
+		free(sample->data);
+		sample->length = 0;
+		sample->data = NULL;
+		mc->voice = -1;
+		return STS_STREAM_COMPLETE;
+	}
+	const int nr_channels = 2;
+	unsigned samples = mc->audio.frame->linesize[0] / mc->bytes_per_sample;
+	if (samples * nr_channels != sample->length) {
+		free(sample->data);
+		sample->length = samples * nr_channels;
+		sample->data = xmalloc(sample->length * mc->bytes_per_sample);
+	}
+	// Interleave.
+	uint8_t *l = mc->audio.frame->data[0];
+	uint8_t *r = mc->audio.frame->data[mc->audio.ctx->channels > 1 ? 1 : 0];
+	uint8_t *out = sample->data;
+	for (unsigned i = 0; i < samples; i++) {
+		memcpy(out, l, mc->bytes_per_sample);
+		out += mc->bytes_per_sample;
+		l += mc->bytes_per_sample;
+		memcpy(out, r, mc->bytes_per_sample);
+		out += mc->bytes_per_sample;
+		r += mc->bytes_per_sample;
+	}
+
+	// Update the timestamp.
+	SDL_LockMutex(mc->timer_mutex);
+	mc->stream_time += (double)samples / mc->audio.ctx->sample_rate;
+	mc->wall_time_ms = SDL_GetTicks();
+	SDL_UnlockMutex(mc->timer_mutex);
+	return STS_STREAM_CONTINUE;
+}
+
+struct movie_context *movie_load(const char *filename)
+{
+	struct movie_context *mc = xcalloc(1, sizeof(struct movie_context));
+	char *path = gamedir_path(filename);
+	int ret;
+	if ((ret = avformat_open_input(&mc->format_ctx, path, NULL, NULL)) != 0) {
+		WARNING("%s: avformat_open_input failed: %d", path, ret);
+		free(path);
+		movie_free(mc);
+		return NULL;
+	}
+	free(path);
+
+	if ((ret = avformat_find_stream_info(mc->format_ctx, NULL)) < 0) {
+		WARNING("avformat_find_stream_info failed: %d", ret);
+		movie_free(mc);
+		return NULL;
+	}
+
+	AVStream *video_stream = NULL;
+	AVStream *audio_stream = NULL;
+	for (int i = 0; i < (int)mc->format_ctx->nb_streams; ++i) {
+		switch (mc->format_ctx->streams[i]->codecpar->codec_type) {
+		case AVMEDIA_TYPE_VIDEO:
+			if (!video_stream)
+				video_stream = mc->format_ctx->streams[i];
+			break;
+		case AVMEDIA_TYPE_AUDIO:
+			if (!audio_stream)
+				audio_stream = mc->format_ctx->streams[i];
+			break;
+		default:
+			break;
+		}
+	}
+	if (!init_decoder(&mc->video, video_stream)) {
+		WARNING("Cannot initialize video decoder");
+		movie_free(mc);
+		return NULL;
+	}
+	if (!init_decoder(&mc->audio, audio_stream)) {
+		WARNING("Cannot initialize audio decoder");
+		movie_free(mc);
+		return NULL;
+	}
+
+	NOTICE("video: %d x %d, %s", mc->video.ctx->width, mc->video.ctx->height, av_get_pix_fmt_name(mc->video.ctx->pix_fmt));
+	NOTICE("audio: %d hz, %d channels, %s", mc->audio.ctx->sample_rate, mc->audio.ctx->channels, av_get_sample_fmt_name(mc->audio.ctx->sample_fmt));
+
+	mc->format_mutex = SDL_CreateMutex();
+	mc->timer_mutex = SDL_CreateMutex();
+	mc->voice = -1;
+	mc->volume = 100;
+
+	preload_packets(mc);
+	return mc;
+}
+
+void movie_free(struct movie_context *mc)
+{
+	if (mc->voice >= 0)
+		mixer_stream_stop(mc->voice);
+	if (mc->sts_stream.sample.data)
+		free(mc->sts_stream.sample.data);
+
+	if (mc->format_ctx)
+		avformat_close_input(&mc->format_ctx);
+	if (mc->format_mutex)
+		SDL_DestroyMutex(mc->format_mutex);
+	if (mc->timer_mutex)
+		SDL_DestroyMutex(mc->timer_mutex);
+
+	free_decoder(&mc->video);
+	free_decoder(&mc->audio);
+
+	if (mc->temp_surface.handle)
+		gfx_delete_texture(&mc->temp_surface);
+	if (mc->sws_ctx)
+		sws_freeContext(mc->sws_ctx);
+	if (mc->sws_frame)
+		av_frame_free(&mc->sws_frame);
+	if (mc->sws_buf)
+		av_free(mc->sws_buf);
+
+	free(mc);
+}
+
+bool movie_play(struct movie_context *mc)
+{
+	// Start the audio stream.
+	mc->stream_time = 0.0;
+	mc->wall_time_ms = SDL_GetTicks();
+	mc->sts_stream.userdata = mc;
+	mc->sts_stream.callback = audio_callback;
+	mc->sts_stream.sample.frequency = mc->audio.ctx->sample_rate;
+	switch (mc->audio.ctx->sample_fmt) {
+	case AV_SAMPLE_FMT_S16P:
+		mc->sts_stream.sample.audio_format = STS_MIXER_SAMPLE_FORMAT_16;
+		mc->bytes_per_sample = 2;
+		break;
+	case AV_SAMPLE_FMT_S32P:
+		mc->sts_stream.sample.audio_format = STS_MIXER_SAMPLE_FORMAT_32;
+		mc->bytes_per_sample = 4;
+		break;
+	case AV_SAMPLE_FMT_FLTP:
+		mc->sts_stream.sample.audio_format = STS_MIXER_SAMPLE_FORMAT_FLOAT;
+		mc->bytes_per_sample = 4;
+		break;
+	default:
+		WARNING("Unsupported audio format %d", mc->audio.ctx->sample_fmt);
+		return false;
+	}
+	mc->voice = mixer_stream_play(&mc->sts_stream, mc->volume);
+	return true;
+}
+
+bool movie_draw(struct movie_context *mc, struct sact_sprite *sprite)
+{
+	struct texture *texture;
+	if (sprite) {
+		texture = sprite_get_texture(sprite);
+	} else {
+		if (!mc->temp_surface.handle)
+			gfx_init_texture_blank(&mc->temp_surface, config.view_width, config.view_height);
+		texture = &mc->temp_surface;
+	}
+
+	if (!mc->sws_ctx) {
+		mc->sws_ctx = sws_getContext(
+			mc->video.ctx->width, mc->video.ctx->height, mc->video.ctx->pix_fmt,
+			texture->w, texture->h, AV_PIX_FMT_RGBA, SWS_BICUBIC, NULL, NULL, NULL);
+		mc->sws_frame = av_frame_alloc();
+		int size = av_image_get_buffer_size(AV_PIX_FMT_RGBA, texture->w, texture->h, 1);
+		mc->sws_buf = av_malloc(size);
+		av_image_fill_arrays(
+			mc->sws_frame->data, mc->sws_frame->linesize,
+			mc->sws_buf, AV_PIX_FMT_RGBA, texture->w, texture->h, 1);
+	}
+
+	// Decode a frame, unless we already have one.
+	if (!mc->has_pending_video_frame && !decode_frame(&mc->video, mc))
+		return mc->video.finished;
+
+	// If the frame's timestamp is in the future, save the frame and return.
+	double pts = av_q2d(mc->video.stream->time_base) * mc->video.frame->best_effort_timestamp;
+	SDL_LockMutex(mc->timer_mutex);
+	double now = mc->stream_time + (SDL_GetTicks() - mc->wall_time_ms) / 1000.0;
+	SDL_UnlockMutex(mc->timer_mutex);
+	if (pts > now) {
+		mc->has_pending_video_frame = true;
+		// We have spare time, let's buffer some packets.
+		preload_packets(mc);
+		return true;
+	}
+
+	// Convert to RGB and update the texture.
+	sws_scale(mc->sws_ctx, (const uint8_t **)mc->video.frame->data, mc->video.frame->linesize,
+		 0, mc->video.ctx->height, mc->sws_frame->data, mc->sws_frame->linesize);
+	gfx_update_texture_with_pixels(texture, mc->sws_buf);
+	mc->has_pending_video_frame = false;
+
+	if (sprite) {
+		sprite_dirty(sprite);
+	} else {
+		// Draw directly to the main framebuffer.
+		gfx_clear();
+		gfx_render_texture(&mc->temp_surface, NULL);
+		gfx_swap();
+	}
+
+	return true;
+}
+
+bool movie_is_end(struct movie_context *mc)
+{
+	return mc->video.finished && mc->audio.finished;
+}
+
+int movie_get_position(struct movie_context *mc)
+{
+	SDL_LockMutex(mc->timer_mutex);
+	int ms = mc->wall_time_ms ? mc->stream_time * 1000 + SDL_GetTicks() - mc->wall_time_ms : 0;
+	SDL_UnlockMutex(mc->timer_mutex);
+	return ms;
+}
+
+bool movie_set_volume(struct movie_context *mc, int volume)
+{
+	mc->volume = volume;
+	if (mc->voice >= 0)
+		mixer_stream_set_volume(mc->voice, volume);
+	return true;
+}

src/video.c

@@ -448,6 +448,12 @@ void gfx_init_texture_with_pixels(struct texture *t, int w, int h, void *pixels)
 	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
 }
 
+void gfx_update_texture_with_pixels(struct texture *t, void *pixels)
+{
+	glBindTexture(GL_TEXTURE_2D, t->handle);
+	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, t->w, t->h, 0, GL_RGBA, GL_UNSIGNED_BYTE, pixels);
+}
+
 void gfx_init_texture_with_cg(struct texture *t, struct cg *cg)
 {
 	gfx_init_texture_with_pixels(t, cg->metrics.w, cg->metrics.h, cg->pixels);