~emersion/vaapi-decoder

ref: c2c800f58f11bd41d1e312f52827f2e3f34ad398 vaapi-decoder/main.c -rw-r--r-- 10.3 KiB
c2c800f5Simon Ser hacky hack 10 months ago
                                                                                
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#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>

#include <drm_fourcc.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavutil/hwcontext.h>
#include <libavutil/hwcontext_drm.h>
#include <libavutil/pixdesc.h>
#include <xcb/xcb.h>
#include <xcb/dri3.h>
#include <xcb/present.h>

#define GAMESCOPE_DMABUF_PROP "GAMESCOPE_DMABUF"

struct gamescope_dmabuf_plane {
	uint32_t stride;
	uint32_t offset;
};

struct gamescope_dmabuf {
	uint32_t format;
	uint64_t modifier;
	uint32_t n_planes;
	struct gamescope_dmabuf_plane planes[4];
};

static enum AVPixelFormat hw_pix_fmt = AV_PIX_FMT_NONE;

static const struct {
	uint32_t format;
	int nb_layers;
	uint32_t layers[AV_DRM_MAX_PLANES];
} drm_format_map[] = {
	{ DRM_FORMAT_NV12, 2, { DRM_FORMAT_R8, DRM_FORMAT_GR88 } },
};

static uint32_t get_drm_frame_format(const AVDRMFrameDescriptor *drm_frame_desc) {
	if (drm_frame_desc->nb_layers == 1) {
		return drm_frame_desc->layers[0].format;
	}
	for (size_t i = 0; i < sizeof(drm_format_map) / sizeof(drm_format_map[0]); i++) {
		if (drm_format_map[i].nb_layers != drm_frame_desc->nb_layers) {
			continue;
		}
		bool match = true;
		for (int j = 0; j < drm_frame_desc->nb_layers; j++) {
			match &= drm_frame_desc->layers[j].format == drm_format_map[i].layers[j];
		}
		if (match) {
			return drm_format_map[i].format;
		}
	}
	return DRM_FORMAT_INVALID;
}

static int check_hw_device_type(enum AVHWDeviceType type) {
	enum AVHWDeviceType t = AV_HWDEVICE_TYPE_NONE;
	while (1) {
		t = av_hwdevice_iterate_types(t);
		if (t == AV_HWDEVICE_TYPE_NONE) {
			break;
		}
		if (t == type) {
			return 0;
		}
	}
	return -1;
}

static enum AVPixelFormat get_hw_format(AVCodecContext *ctx,
		const enum AVPixelFormat *pix_fmts) {
	for (size_t i = 0; pix_fmts[i] != AV_PIX_FMT_NONE; i++) {
		if (pix_fmts[i] == hw_pix_fmt) {
			return hw_pix_fmt;
		}
	}

	fprintf(stderr, "Failed to find HW pixel format\n");
	return AV_PIX_FMT_NONE;
}

static int decode_frame(AVFormatContext *input_ctx, int video_stream,
		AVCodecContext *decoder_ctx, AVFrame **frame_ptr) {
	int ret;
	while (1) {
		AVPacket packet;
		ret = av_read_frame(input_ctx, &packet);
		if (ret < 0) {
			fprintf(stderr, "Failed to read frames into packet\n");
			return ret;
		}

		if (video_stream != packet.stream_index) {
			av_packet_unref(&packet);
			continue;
		}

		ret = avcodec_send_packet(decoder_ctx, &packet);
		if (ret < 0) {
			fprintf(stderr, "Failed to send packet to decoder\n");
			return ret;
		}
		av_packet_unref(&packet);

		AVFrame *frame = av_frame_alloc();
		if (!frame) {
			fprintf(stderr, "Failed to allocate frame\n");
			return AVERROR(ENOMEM);
		}

		while (1) {
			ret = avcodec_receive_frame(decoder_ctx, frame);
			if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
				break;
			} else if (ret < 0) {
				fprintf(stderr, "Failed to receive frame from decoder\n");
				return ret;
			}

			if (frame->format != hw_pix_fmt) {
				continue;
			}

			*frame_ptr = frame;
			return 0;
		}

		av_frame_free(&frame);
	}

	return AVERROR_EOF;
}

static xcb_depth_t *get_depth(xcb_screen_t *screen, uint8_t depth) {
	xcb_depth_iterator_t iter = xcb_screen_allowed_depths_iterator(screen);
	while (iter.rem > 0) {
		if (iter.data->depth == depth) {
			return iter.data;
		}
		xcb_depth_next(&iter);
	}
	return NULL;
}

static xcb_visualid_t pick_visualid(xcb_depth_t *depth) {
	xcb_visualtype_t *visuals = xcb_depth_visuals(depth);
	for (int i = 0; i < xcb_depth_visuals_length(depth); i++) {
		if (visuals[i]._class == XCB_VISUAL_CLASS_TRUE_COLOR) {
			return visuals[i].visual_id;
		}
	}
	return 0;
}

int main(int argc, char *argv[]) {
	if (argc < 2) {
		fprintf(stderr, "usage: %s <file>\n", argv[0]);
		return 1;
	}

	enum AVHWDeviceType type = AV_HWDEVICE_TYPE_VAAPI;
	int ret = check_hw_device_type(type);
	if (ret != 0) {
		fprintf(stderr, "VA-API not supported\n");
		return 1;
	}

	AVFormatContext *input_ctx = NULL;
	if (avformat_open_input(&input_ctx, argv[1], NULL, NULL) != 0) {
		fprintf(stderr, "Failed to open input file\n");
		return 1;
	}

	if (avformat_find_stream_info(input_ctx, NULL) < 0) {
		fprintf(stderr, "Failed to find input stream info\n");
		return 1;
	}

	AVCodec *decoder = NULL;
	int video_stream = av_find_best_stream(input_ctx, AVMEDIA_TYPE_VIDEO,
		-1, -1, &decoder, 0);
	if (video_stream < 0) {
		fprintf(stderr, "Failed to find video stream in input file\n");
		return 1;
	}
	fprintf(stderr, "Selected decoder %s\n", decoder->name);

	int i = 0;
	while (1) {
		const AVCodecHWConfig *config = avcodec_get_hw_config(decoder, i);
		if (!config) {
			fprintf(stderr, "Decoder %s doesn't support device type %s\n",
				decoder->name, av_hwdevice_get_type_name(type));
			return 1;
		}

		if ((config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX) &&
				config->device_type == type) {
			hw_pix_fmt = config->pix_fmt;
			break;
		}

		i++;
	}
	fprintf(stderr, "Selected pixel format %s\n", av_get_pix_fmt_name(hw_pix_fmt));

	AVCodecContext *decoder_ctx = avcodec_alloc_context3(decoder);
	if (!decoder_ctx) {
		fprintf(stderr, "Failed to allocate decoder context\n");
		return 1;
	}

	AVStream *video = input_ctx->streams[video_stream];
	if (avcodec_parameters_to_context(decoder_ctx, video->codecpar) < 0) {
		fprintf(stderr, "Failed to fill decoder context from video parameters\n");
		return 1;
	}

	decoder_ctx->get_format = get_hw_format;

	AVBufferRef *hw_device_ctx = NULL;
	ret = av_hwdevice_ctx_create(&hw_device_ctx, type, NULL, NULL, 0);
	if (ret < 0) {
		fprintf(stderr, "Failed to create HW device context\n");
		return 1;
	}
	decoder_ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);

	ret = avcodec_open2(decoder_ctx, decoder, NULL);
	if (ret < 0) {
		fprintf(stderr, "Failed to open codec for stream #%u\n", video_stream);
		return 1;
	}

	xcb_connection_t *conn = xcb_connect(NULL, NULL);
	if (!conn || xcb_connection_has_error(conn)) {
		fprintf(stderr, "Failed to connect to X11 display\n");
		return 1;
	}

	xcb_screen_t *screen = xcb_setup_roots_iterator(xcb_get_setup(conn)).data;

	xcb_depth_t *depth = get_depth(screen, 24);
	if (!depth) {
		fprintf(stderr, "Failed to find depth\n");
		return 1;
	}
	xcb_visualid_t visualid = pick_visualid(depth);
	if (!visualid) {
		fprintf(stderr, "Failed to find visualid\n");
		return 1;
	}

	xcb_colormap_t colormap = xcb_generate_id(conn);
	xcb_create_colormap(conn, XCB_COLORMAP_ALLOC_NONE, colormap, screen->root, visualid);

	uint32_t mask = XCB_CW_BORDER_PIXEL | XCB_CW_COLORMAP;
	uint32_t values[] = { 0, colormap };

	xcb_window_t win = xcb_generate_id(conn);
	xcb_create_window(conn, depth->depth, win, screen->root, 0, 0, 1920, 1080, 0, XCB_WINDOW_CLASS_INPUT_OUTPUT, visualid, mask, values);
	xcb_map_window(conn, win);
	xcb_flush(conn);

	xcb_intern_atom_cookie_t cookie = xcb_intern_atom(conn, true, strlen(GAMESCOPE_DMABUF_PROP), GAMESCOPE_DMABUF_PROP);
	xcb_intern_atom_reply_t *reply = xcb_intern_atom_reply(conn, cookie, NULL);
	xcb_atom_t gamescope_dmabuf_prop = reply->atom;

	AVFrame *frame = NULL;
	ret = decode_frame(input_ctx, video_stream, decoder_ctx, &frame);
	if (ret < 0) {
		return 1;
	}

	fprintf(stderr, "Got %dx%d frame!\n", frame->width, frame->height);

	AVFrame *drm_frame = av_frame_alloc();
	drm_frame->format = AV_PIX_FMT_DRM_PRIME;
	drm_frame->hw_frames_ctx = av_buffer_ref(frame->hw_frames_ctx);

	// Convert the VA-API frame into a DMA-BUF frame
	ret = av_hwframe_map(drm_frame, frame, 0);
	if (ret < 0) {
		fprintf(stderr, "Failed to map frame: %s\n", av_err2str(ret));
		return 1;
	}

	AVDRMFrameDescriptor *drm_frame_desc = (void *)drm_frame->data[0];
	fprintf(stderr, "DRM frame:\n");
	for (int i = 0; i < drm_frame_desc->nb_objects; i++) {
		AVDRMObjectDescriptor *drm_object = &drm_frame_desc->objects[i];
		fprintf(stderr, "  object #%i: fd = %d, size = %zu, "
			"format_modifier = 0x%lX\n", i, drm_object->fd,
			drm_object->size, drm_object->format_modifier);
	}
	for (int i = 0; i < drm_frame_desc->nb_layers; i++) {
		AVDRMLayerDescriptor *drm_layer = &drm_frame_desc->layers[i];
		fprintf(stderr, "  layer #%d: format = 0x%X\n",
			i, drm_layer->format);
		for (int j = 0; j < drm_layer->nb_planes; j++) {
			AVDRMPlaneDescriptor *drm_plane = &drm_layer->planes[j];
			fprintf(stderr, "    plane #%d: object_index = %d, "
				"offset = %ld, pitch = %ld\n", j, drm_plane->object_index,
				drm_plane->offset, drm_plane->pitch);
		}
	}

	// VA-API drivers may use separate layers with one plane each, or a single
	// layer with multiple planes. We need to handle both.
	uint32_t drm_format = get_drm_frame_format(drm_frame_desc);
	if (drm_format == DRM_FORMAT_INVALID) {
		fprintf(stderr, "Failed to get DRM frame format\n");
		return 1;
	}
	fprintf(stderr, "DRM format: 0x%X\n", drm_format);

	if (drm_format != DRM_FORMAT_NV12) {
		fprintf(stderr, "Only NV12 is supported\n");
		return 1;
	}

	int fd = dup(drm_frame_desc->objects[0].fd);
	uint32_t size = lseek(fd, 0, SEEK_END);
	uint8_t frame_depth = 16;
	uint8_t frame_bpp = 16;
	uint16_t stride = drm_frame_desc->layers[0].planes[0].pitch;

	struct gamescope_dmabuf gamescope_dmabuf = {
		.format = drm_format,
		.modifier = drm_frame_desc->objects[0].format_modifier,
	};
	int k = 0;
	for (int i = 0; i < drm_frame_desc->nb_layers; i++) {
		AVDRMLayerDescriptor *drm_layer = &drm_frame_desc->layers[i];
		for (int j = 0; j < drm_layer->nb_planes; j++) {
			AVDRMPlaneDescriptor *drm_plane = &drm_layer->planes[j];
			gamescope_dmabuf.planes[k] = (struct gamescope_dmabuf_plane){
				.offset = drm_plane->offset,
				.stride = drm_plane->pitch,
			};
			k++;
		}
	}
	gamescope_dmabuf.n_planes = k;

	xcb_change_property(conn, XCB_PROP_MODE_REPLACE, win, gamescope_dmabuf_prop, XCB_ATOM_NONE, 8, sizeof(gamescope_dmabuf), &gamescope_dmabuf);

	xcb_pixmap_t pixmap = xcb_generate_id(conn);
	xcb_dri3_pixmap_from_buffer(conn, pixmap, win, size, drm_frame->width,
		drm_frame->height, stride, frame_depth, frame_bpp, fd);

	uint32_t serial = 0;
	uint32_t options = 0;
	uint64_t target_msc = 0;
	xcb_present_pixmap(conn, win, pixmap, serial, 0, XCB_NONE, 0, 0, XCB_NONE, XCB_NONE, XCB_NONE, options, target_msc, 0, 0, 0, NULL);

	xcb_flush(conn);

	for (int i = 0; i < drm_frame_desc->nb_objects; i++) {
		close(drm_frame_desc->objects[i].fd);
		drm_frame_desc->objects[i].fd = -1;
	}

	av_frame_free(&drm_frame);
	av_frame_free(&frame);

	while (1) {
		xcb_generic_event_t *event = xcb_wait_for_event(conn);
		if (!event) {
			break;
		}
		free(event);
	}

	avcodec_free_context(&decoder_ctx);
	avformat_close_input(&input_ctx);
	av_buffer_unref(&hw_device_ctx);

	return 0;
}