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pipewire/spa/examples/local-v4l2.c
Wim Taymans 9592b0af2a examples: fix mapoffset in examples 
The mapoffset should be using in the mmap call as the offset.

Mapping the whole memory before the offset and then ignoring the part
before it seems like it can work but it actually has some problems:

1. some drivers (v4l2) use the mapoffset to calculate the buffer to map
2. we waste resources for mapped but unused pages.

The problem with the mapoffset is that it needs to be page aligned and
that used to be a problem in the past. Nowadays PipeWire no longer set
the mapoffset for any of the memory that it allocates.
2024-06-13 10:11:29 +02:00

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/* Spa */
/* SPDX-FileCopyrightText: Copyright © 2018 Wim Taymans */
/* SPDX-License-Identifier: MIT */
/*
[title]
Example using libspa-v4l2, with only \ref api_spa
[title]
*/
#include "config.h"
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <dlfcn.h>
#include <poll.h>
#include <pthread.h>
#include <errno.h>
#include <sys/mman.h>
#include <SDL2/SDL.h>
#include <spa/support/plugin.h>
#include <spa/utils/names.h>
#include <spa/utils/result.h>
#include <spa/utils/string.h>
#include <spa/support/log-impl.h>
#include <spa/support/loop.h>
#include <spa/node/node.h>
#include <spa/node/io.h>
#include <spa/node/utils.h>
#include <spa/param/param.h>
#include <spa/param/props.h>
#include <spa/param/video/format-utils.h>
#include <spa/debug/pod.h>
static SPA_LOG_IMPL(default_log);
#define MAX_BUFFERS 8
struct buffer {
struct spa_buffer buffer;
struct spa_meta metas[1];
struct spa_meta_header header;
struct spa_data datas[1];
struct spa_chunk chunks[1];
SDL_Texture *texture;
};
struct data {
const char *plugin_dir;
struct spa_log *log;
struct spa_system *system;
struct spa_loop *loop;
struct spa_loop_control *control;
struct spa_support support[5];
uint32_t n_support;
struct spa_node *source;
struct spa_hook listener;
struct spa_io_buffers source_output[1];
SDL_Renderer *renderer;
SDL_Window *window;
SDL_Texture *texture;
bool use_buffer;
bool running;
pthread_t thread;
struct spa_buffer *bp[MAX_BUFFERS];
struct buffer buffers[MAX_BUFFERS];
unsigned int n_buffers;
};
static int load_handle(struct data *data, struct spa_handle **handle, const char *lib, const char *name)
{
int res;
void *hnd;
spa_handle_factory_enum_func_t enum_func;
uint32_t i;
char *path = NULL;
if ((path = spa_aprintf("%s/%s", data->plugin_dir, lib)) == NULL) {
return -ENOMEM;
}
if ((hnd = dlopen(path, RTLD_NOW)) == NULL) {
printf("can't load %s: %s\n", path, dlerror());
free(path);
return -ENOENT;
}
free(path);
if ((enum_func = dlsym(hnd, SPA_HANDLE_FACTORY_ENUM_FUNC_NAME)) == NULL) {
printf("can't find enum function\n");
return -ENOENT;
}
for (i = 0;;) {
const struct spa_handle_factory *factory;
if ((res = enum_func(&factory, &i)) <= 0) {
if (res != 0)
printf("can't enumerate factories: %s\n", spa_strerror(res));
break;
}
if (factory->version < 1)
continue;
if (!spa_streq(factory->name, name))
continue;
*handle = calloc(1, spa_handle_factory_get_size(factory, NULL));
if ((res = spa_handle_factory_init(factory, *handle,
NULL, data->support,
data->n_support)) < 0) {
printf("can't make factory instance: %d\n", res);
return res;
}
return 0;
}
return -EBADF;
}
static int make_node(struct data *data, struct spa_node **node, const char *lib, const char *name)
{
struct spa_handle *handle = NULL;
void *iface;
int res;
if ((res = load_handle(data, &handle, lib, name)) < 0)
return res;
if ((res = spa_handle_get_interface(handle, SPA_TYPE_INTERFACE_Node, &iface)) < 0) {
printf("can't get interface %d\n", res);
return res;
}
*node = iface;
return 0;
}
static int on_source_ready(void *_data, int status)
{
struct data *data = _data;
int res;
struct buffer *b;
void *sdata, *ddata;
int sstride, dstride;
int i;
uint8_t *src, *dst;
struct spa_data *datas;
struct spa_io_buffers *io = &data->source_output[0];
if (io->status != SPA_STATUS_HAVE_DATA ||
io->buffer_id >= MAX_BUFFERS)
return -EINVAL;
b = &data->buffers[io->buffer_id];
io->status = SPA_STATUS_NEED_DATA;
datas = b->buffer.datas;
if (b->texture) {
SDL_Texture *texture = b->texture;
SDL_UnlockTexture(texture);
SDL_RenderClear(data->renderer);
SDL_RenderCopy(data->renderer, texture, NULL, NULL);
SDL_RenderPresent(data->renderer);
if (SDL_LockTexture(texture, NULL, &sdata, &sstride) < 0) {
fprintf(stderr, "Couldn't lock texture: %s\n", SDL_GetError());
return -EIO;
}
} else {
uint8_t *map;
if (SDL_LockTexture(data->texture, NULL, &ddata, &dstride) < 0) {
fprintf(stderr, "Couldn't lock texture: %s\n", SDL_GetError());
return -EIO;
}
sdata = datas[0].data;
if (datas[0].type == SPA_DATA_MemFd ||
datas[0].type == SPA_DATA_DmaBuf) {
map = mmap(NULL, datas[0].maxsize, PROT_READ,
MAP_PRIVATE, datas[0].fd, datas[0].mapoffset);
if (map == MAP_FAILED)
return -errno;
sdata = map;
} else if (datas[0].type == SPA_DATA_MemPtr) {
map = NULL;
sdata = datas[0].data;
} else
return -EIO;
sstride = datas[0].chunk->stride;
for (i = 0; i < 240; i++) {
src = ((uint8_t *) sdata + i * sstride);
dst = ((uint8_t *) ddata + i * dstride);
memcpy(dst, src, SPA_MIN(sstride, dstride));
}
SDL_UnlockTexture(data->texture);
SDL_RenderClear(data->renderer);
SDL_RenderCopy(data->renderer, data->texture, NULL, NULL);
SDL_RenderPresent(data->renderer);
if (map)
munmap(map, datas[0].maxsize);
}
if ((res = spa_node_process(data->source)) < 0)
printf("got process error %d\n", res);
return 0;
}
static const struct spa_node_callbacks source_callbacks = {
SPA_VERSION_NODE_CALLBACKS,
.ready = on_source_ready,
};
static int make_nodes(struct data *data, const char *device)
{
int res;
struct spa_pod *props;
struct spa_pod_builder b = { 0 };
uint8_t buffer[256];
uint32_t index;
if ((res =
make_node(data, &data->source,
"v4l2/libspa-v4l2.so",
SPA_NAME_API_V4L2_SOURCE)) < 0) {
printf("can't create v4l2-source: %d\n", res);
return res;
}
spa_node_set_callbacks(data->source, &source_callbacks, data);
index = 0;
spa_pod_builder_init(&b, buffer, sizeof(buffer));
if ((res = spa_node_enum_params_sync(data->source, SPA_PARAM_Props,
&index, NULL, &props, &b)) == 1) {
spa_debug_pod(0, NULL, props);
}
spa_pod_builder_init(&b, buffer, sizeof(buffer));
props = spa_pod_builder_add_object(&b,
SPA_TYPE_OBJECT_Props, 0,
SPA_PROP_device, SPA_POD_String(device ? device : "/dev/video0"));
if ((res = spa_node_set_param(data->source, SPA_PARAM_Props, 0, props)) < 0)
printf("got set_props error %d\n", res);
return res;
}
static int setup_buffers(struct data *data)
{
int i;
for (i = 0; i < MAX_BUFFERS; i++) {
struct buffer *b = &data->buffers[i];
data->bp[i] = &b->buffer;
b->texture = NULL;
b->buffer.metas = b->metas;
b->buffer.n_metas = 1;
b->buffer.datas = b->datas;
b->buffer.n_datas = 1;
b->header.flags = 0;
b->header.seq = 0;
b->header.pts = 0;
b->header.dts_offset = 0;
b->metas[0].type = SPA_META_Header;
b->metas[0].data = &b->header;
b->metas[0].size = sizeof(b->header);
b->datas[0].type = 0;
b->datas[0].flags = 0;
b->datas[0].fd = -1;
b->datas[0].mapoffset = 0;
b->datas[0].maxsize = 0;
b->datas[0].data = NULL;
b->datas[0].chunk = &b->chunks[0];
b->datas[0].chunk->offset = 0;
b->datas[0].chunk->size = 0;
b->datas[0].chunk->stride = 0;
}
data->n_buffers = MAX_BUFFERS;
return 0;
}
static int sdl_alloc_buffers(struct data *data)
{
int i;
for (i = 0; i < MAX_BUFFERS; i++) {
struct buffer *b = &data->buffers[i];
SDL_Texture *texture;
void *ptr;
int stride;
texture = SDL_CreateTexture(data->renderer,
SDL_PIXELFORMAT_YUY2,
SDL_TEXTUREACCESS_STREAMING, 320, 240);
if (!texture) {
printf("can't create texture: %s\n", SDL_GetError());
return -ENOMEM;
}
if (SDL_LockTexture(texture, NULL, &ptr, &stride) < 0) {
fprintf(stderr, "Couldn't lock texture: %s\n", SDL_GetError());
return -EIO;
}
b->texture = texture;
b->datas[0].type = SPA_DATA_MemPtr;
b->datas[0].maxsize = stride * 240;
b->datas[0].data = ptr;
b->datas[0].chunk->offset = 0;
b->datas[0].chunk->size = stride * 240;
b->datas[0].chunk->stride = stride;
}
return 0;
}
static int negotiate_formats(struct data *data)
{
int res;
struct spa_pod *format;
uint8_t buffer[256];
struct spa_pod_builder b = SPA_POD_BUILDER_INIT(buffer, sizeof(buffer));
data->source_output[0] = SPA_IO_BUFFERS_INIT;
if ((res =
spa_node_port_set_io(data->source,
SPA_DIRECTION_OUTPUT, 0,
SPA_IO_Buffers,
&data->source_output[0], sizeof(data->source_output[0]))) < 0)
return res;
format = spa_format_video_raw_build(&b, 0,
&SPA_VIDEO_INFO_RAW_INIT(
.format = SPA_VIDEO_FORMAT_YUY2,
.size = SPA_RECTANGLE(320, 240),
.framerate = SPA_FRACTION(25,1)));
if ((res = spa_node_port_set_param(data->source,
SPA_DIRECTION_OUTPUT, 0,
SPA_PARAM_Format, 0,
format)) < 0)
return res;
setup_buffers(data);
if (data->use_buffer) {
if ((res = sdl_alloc_buffers(data)) < 0)
return res;
if ((res = spa_node_port_use_buffers(data->source,
SPA_DIRECTION_OUTPUT, 0, 0,
data->bp, data->n_buffers)) < 0) {
printf("can't allocate buffers: %s\n", spa_strerror(res));
return -1;
}
} else {
unsigned int n_buffers;
data->texture = SDL_CreateTexture(data->renderer,
SDL_PIXELFORMAT_YUY2,
SDL_TEXTUREACCESS_STREAMING, 320, 240);
if (!data->texture) {
printf("can't create texture: %s\n", SDL_GetError());
return -1;
}
n_buffers = MAX_BUFFERS;
if ((res = spa_node_port_use_buffers(data->source,
SPA_DIRECTION_OUTPUT, 0,
SPA_NODE_BUFFERS_FLAG_ALLOC,
data->bp, n_buffers)) < 0) {
printf("can't allocate buffers: %s\n", spa_strerror(res));
return -1;
}
data->n_buffers = n_buffers;
}
return 0;
}
static void *loop(void *user_data)
{
struct data *data = user_data;
printf("enter thread\n");
spa_loop_control_enter(data->control);
while (data->running) {
spa_loop_control_iterate(data->control, -1);
}
printf("leave thread\n");
spa_loop_control_leave(data->control);
return NULL;
}
static void run_async_source(struct data *data)
{
int res, err;
struct spa_command cmd;
SDL_Event event;
bool running = true;
cmd = SPA_NODE_COMMAND_INIT(SPA_NODE_COMMAND_Start);
if ((res = spa_node_send_command(data->source, &cmd)) < 0)
printf("got error %d\n", res);
spa_loop_control_leave(data->control);
data->running = true;
if ((err = pthread_create(&data->thread, NULL, loop, data)) != 0) {
printf("can't create thread: %d %s", err, strerror(err));
data->running = false;
}
while (running && SDL_WaitEvent(&event)) {
switch (event.type) {
case SDL_QUIT:
running = false;
break;
}
}
if (data->running) {
data->running = false;
pthread_join(data->thread, NULL);
}
spa_loop_control_enter(data->control);
cmd = SPA_NODE_COMMAND_INIT(SPA_NODE_COMMAND_Pause);
if ((res = spa_node_send_command(data->source, &cmd)) < 0)
printf("got error %d\n", res);
}
int main(int argc, char *argv[])
{
struct data data = { 0 };
int res;
const char *str;
struct spa_handle *handle = NULL;
void *iface;
if ((str = getenv("SPA_PLUGIN_DIR")) == NULL)
str = PLUGINDIR;
data.plugin_dir = str;
if ((res = load_handle(&data, &handle,
"support/libspa-support.so",
SPA_NAME_SUPPORT_SYSTEM)) < 0)
return res;
if ((res = spa_handle_get_interface(handle, SPA_TYPE_INTERFACE_System, &iface)) < 0) {
printf("can't get System interface %d\n", res);
return res;
}
data.system = iface;
data.support[data.n_support++] = SPA_SUPPORT_INIT(SPA_TYPE_INTERFACE_System, data.system);
if ((res = load_handle(&data, &handle,
"support/libspa-support.so",
SPA_NAME_SUPPORT_LOOP)) < 0)
return res;
if ((res = spa_handle_get_interface(handle, SPA_TYPE_INTERFACE_Loop, &iface)) < 0) {
printf("can't get interface %d\n", res);
return res;
}
data.loop = iface;
if ((res = spa_handle_get_interface(handle, SPA_TYPE_INTERFACE_LoopControl, &iface)) < 0) {
printf("can't get interface %d\n", res);
return res;
}
data.control = iface;
data.use_buffer = true;
data.log = &default_log.log;
if ((str = getenv("SPA_DEBUG")))
data.log->level = atoi(str);
data.support[data.n_support++] = SPA_SUPPORT_INIT(SPA_TYPE_INTERFACE_Log, data.log);
data.support[data.n_support++] = SPA_SUPPORT_INIT(SPA_TYPE_INTERFACE_Loop, data.loop);
data.support[data.n_support++] = SPA_SUPPORT_INIT(SPA_TYPE_INTERFACE_DataLoop, data.loop);
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
printf("can't initialize SDL: %s\n", SDL_GetError());
return -1;
}
if (SDL_CreateWindowAndRenderer
(320, 240, SDL_WINDOW_RESIZABLE, &data.window, &data.renderer)) {
printf("can't create window: %s\n", SDL_GetError());
return -1;
}
if ((res = make_nodes(&data, argv[1])) < 0) {
printf("can't make nodes: %d\n", res);
return -1;
}
if ((res = negotiate_formats(&data)) < 0) {
printf("can't negotiate nodes: %d\n", res);
return -1;
}
spa_loop_control_enter(data.control);
run_async_source(&data);
spa_loop_control_leave(data.control);
SDL_DestroyRenderer(data.renderer);
return 0;
}
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