webrtc/modules/portal/pipewire_utils.h
Jan Grulich 334e9133dc Video capture PipeWire: add support for DMABuf buffer type
Announce that we support SPA_DATA_DmaBuf and tell PipeWire not to map
memory for us so we can handle it ourself, similar like we do in case of
screen sharing. This fixes an issue when a camera is already in use by
gstreamer (pipewiresrc), where DMABufs are used, and we try to share
same camera and get no content, as PipeWire doesn't want to mmap DMABuf
memory for us and we get NULL data pointers.

Firefox bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1876895

Bug: webrtc:15654
Change-Id: I788d8d12b2fcd5588329d7265e45b479f74bb628
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/338921
Commit-Queue: Jan Grulich <grulja@gmail.com>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Reviewed-by: Alexander Cooper <alcooper@chromium.org>
Cr-Commit-Position: refs/heads/main@{#41826}
2024-02-27 18:31:26 +00:00

112 lines
2.8 KiB
C++

/*
* Copyright 2022 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef MODULES_PORTAL_PIPEWIRE_UTILS_H_
#define MODULES_PORTAL_PIPEWIRE_UTILS_H_
#include <errno.h>
#include <stdint.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
// static
struct dma_buf_sync {
uint64_t flags;
};
#define DMA_BUF_SYNC_READ (1 << 0)
#define DMA_BUF_SYNC_START (0 << 2)
#define DMA_BUF_SYNC_END (1 << 2)
#define DMA_BUF_BASE 'b'
#define DMA_BUF_IOCTL_SYNC _IOW(DMA_BUF_BASE, 0, struct dma_buf_sync)
struct pw_thread_loop;
namespace webrtc {
constexpr int kInvalidPipeWireFd = -1;
// Prepare PipeWire so that it is ready to be used. If it needs to be dlopen'd
// this will do so. Note that this does not guarantee a PipeWire server is
// running nor does it establish a connection to one.
bool InitializePipeWire();
// Locks pw_thread_loop in the current scope
class PipeWireThreadLoopLock {
public:
explicit PipeWireThreadLoopLock(pw_thread_loop* loop);
~PipeWireThreadLoopLock();
private:
pw_thread_loop* const loop_;
};
// We should synchronize DMA Buffer object access from CPU to avoid potential
// cache incoherency and data loss.
// See
// https://01.org/linuxgraphics/gfx-docs/drm/driver-api/dma-buf.html#cpu-access-to-dma-buffer-objects
static bool SyncDmaBuf(int fd, uint64_t start_or_end) {
struct dma_buf_sync sync = {0};
sync.flags = start_or_end | DMA_BUF_SYNC_READ;
while (true) {
int ret;
ret = ioctl(fd, DMA_BUF_IOCTL_SYNC, &sync);
if (ret == -1 && errno == EINTR) {
continue;
} else if (ret == -1) {
return false;
} else {
break;
}
}
return true;
}
class ScopedBuf {
public:
ScopedBuf() {}
ScopedBuf(uint8_t* map, int map_size, int fd, bool is_dma_buf = false)
: map_(map), map_size_(map_size), fd_(fd), is_dma_buf_(is_dma_buf) {}
~ScopedBuf() {
if (map_ != MAP_FAILED) {
if (is_dma_buf_) {
SyncDmaBuf(fd_, DMA_BUF_SYNC_END);
}
munmap(map_, map_size_);
}
}
explicit operator bool() { return map_ != MAP_FAILED; }
void initialize(uint8_t* map, int map_size, int fd, bool is_dma_buf = false) {
map_ = map;
map_size_ = map_size;
is_dma_buf_ = is_dma_buf;
fd_ = fd;
if (is_dma_buf_) {
SyncDmaBuf(fd_, DMA_BUF_SYNC_START);
}
}
uint8_t* get() { return map_; }
protected:
uint8_t* map_ = static_cast<uint8_t*>(MAP_FAILED);
int map_size_;
int fd_;
bool is_dma_buf_;
};
} // namespace webrtc
#endif // MODULES_PORTAL_PIPEWIRE_UTILS_H_