[libcamera-devel] [PATCH v2] cam: sdl_sink: Add SDL sink
Laurent Pinchart
laurent.pinchart at ideasonboard.com
Wed Mar 23 01:35:50 CET 2022
On Tue, Mar 22, 2022 at 11:34:28PM +0000, Kieran Bingham via libcamera-devel wrote:
> Hi Eric,
>
> Quoting Eric Curtin via libcamera-devel (2022-03-22 19:09:36)
> > This adds more portability to existing cam sinks. You can pass a
> > YUYV camera buffer for example and SDL will handle the pixel buffer
> > conversion, although SDL does not support decompression for pixelformats
> > like MJPEG. This allows cam reference implementation to display images
> > on VMs, Mac M1, Raspberry Pi, etc. This also enables cam reference
> > implementation, to run as a desktop application in wayland or x11.
> > SDL also has support for Android and ChromeOS which I have not tested.
> > Also tested on simpledrm raspberry pi 4 framebuffer successfully where
> > existing kms sink did not work.
>
> This sounds very helpful and useful to me...
>
> > Signed-off-by: Eric Curtin <ecurtin at redhat.com>
> > ---
> > Changes in v2:
> > - Remove hardcoded pixel format from SDL_CreateTexture call
> > ---
> > src/cam/camera_session.cpp | 8 +++
> > src/cam/main.cpp | 6 ++
> > src/cam/main.h | 1 +
> > src/cam/meson.build | 10 +++
> > src/cam/sdl_sink.cpp | 125 +++++++++++++++++++++++++++++++++++++
> > src/cam/sdl_sink.h | 40 ++++++++++++
> > 6 files changed, 190 insertions(+)
> > create mode 100644 src/cam/sdl_sink.cpp
> > create mode 100644 src/cam/sdl_sink.h
> >
> > diff --git a/src/cam/camera_session.cpp b/src/cam/camera_session.cpp
> > index 0428b538..30162dbd 100644
> > --- a/src/cam/camera_session.cpp
> > +++ b/src/cam/camera_session.cpp
> > @@ -19,6 +19,9 @@
> > #ifdef HAVE_KMS
> > #include "kms_sink.h"
> > #endif
> > +#ifdef HAVE_SDL
> > +#include "sdl_sink.h"
> > +#endif
> > #include "main.h"
> > #include "stream_options.h"
> >
> > @@ -187,6 +190,11 @@ int CameraSession::start()
> > sink_ = std::make_unique<KMSSink>(options_[OptDisplay].toString());
> > #endif
> >
> > +#ifdef HAVE_SDL
> > + if (options_.isSet(OptSDL))
> > + sink_ = std::make_unique<SDLSink>();
> > +#endif
> > +
> > if (options_.isSet(OptFile)) {
> > if (!options_[OptFile].toString().empty())
> > sink_ = std::make_unique<FileSink>(streamNames_,
> > diff --git a/src/cam/main.cpp b/src/cam/main.cpp
> > index c7f664b9..406d61bc 100644
> > --- a/src/cam/main.cpp
> > +++ b/src/cam/main.cpp
> > @@ -138,6 +138,12 @@ int CamApp::parseOptions(int argc, char *argv[])
> > "display", ArgumentOptional, "connector", false,
> > OptCamera);
> > #endif
> > +
You can drop the blank line here.
> > +#ifdef HAVE_SDL
> > + parser.addOption(OptSDL, OptionNone,
> > + "Display viewfinder through SDL",
> > + "sdl", ArgumentNone, "", false, OptCamera);
> > +#endif
> > parser.addOption(OptFile, OptionString,
> > "Write captured frames to disk\n"
> > "If the file name ends with a '/', it sets the directory in which\n"
> > diff --git a/src/cam/main.h b/src/cam/main.h
> > index 62f7bbc9..a64f95a0 100644
> > --- a/src/cam/main.h
> > +++ b/src/cam/main.h
> > @@ -11,6 +11,7 @@ enum {
> > OptCamera = 'c',
> > OptCapture = 'C',
> > OptDisplay = 'D',
> > + OptSDL = 'S',
> > OptFile = 'F',
> > OptHelp = 'h',
> > OptInfo = 'I',
> > diff --git a/src/cam/meson.build b/src/cam/meson.build
> > index e8e2ae57..44202ef0 100644
> > --- a/src/cam/meson.build
> > +++ b/src/cam/meson.build
> > @@ -32,11 +32,21 @@ cam_sources += files([
> > ])
> > endif
> >
> > +libsdl2 = dependency('SDL2', required : false)
> > +
> > +if libsdl2.found()
> > +cam_cpp_args += [ '-DHAVE_SDL' ]
> > +cam_sources += files([
> > + 'sdl_sink.cpp'
> > +])
The contents of the if..endif should be indented.
> > +endif
> > +
> > cam = executable('cam', cam_sources,
> > dependencies : [
> > libatomic,
> > libcamera_public,
> > libdrm,
> > + libsdl2,
> > libevent,
> > ],
> > cpp_args : cam_cpp_args,
> > diff --git a/src/cam/sdl_sink.cpp b/src/cam/sdl_sink.cpp
> > new file mode 100644
> > index 00000000..480df1b4
> > --- /dev/null
> > +++ b/src/cam/sdl_sink.cpp
> > @@ -0,0 +1,125 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +/*
> > + * sdl_sink.cpp - SDL Sink
> > + */
> > +
> > +#include "sdl_sink.h"
> > +
> > +#include <assert.h>
> > +#include <fcntl.h>
> > +#include <iomanip>
> > +#include <iostream>
> > +#include <signal.h>
> > +#include <sstream>
> > +#include <string.h>
> > +#include <unistd.h>
> > +
> > +#include <libcamera/camera.h>
> > +#include <libcamera/formats.h>
> > +
> > +#include "image.h"
> > +
> > +using namespace libcamera;
> > +
> > +SDLSink::SDLSink()
> > +{
> > + memset(&sdlRect_, 0, sizeof(sdlRect_));
> > +}
> > +
> > +SDLSink::~SDLSink()
> > +{
> > + SDL_Quit();
> > +}
> > +
> > +int SDLSink::configure(const libcamera::CameraConfiguration &cfg)
> > +{
> > + int ret = FrameSink::configure(cfg);
> > + if (ret < 0)
> > + return ret;
> > +
> > + if ((ret = SDL_Init(SDL_INIT_VIDEO))) {
> > + std::cout << "Could not initialize SDL - " << SDL_GetError() << "\n";
> > + return ret;
> > + }
> > +
> > + const libcamera::StreamConfiguration &sCfg = cfg.at(0);
> > + sdlScreen_ = SDL_CreateWindow("", SDL_WINDOWPOS_UNDEFINED,
> > + SDL_WINDOWPOS_UNDEFINED, sCfg.size.width,
> > + sCfg.size.height, SDL_WINDOW_SHOWN | SDL_WINDOW_RESIZABLE);
As this shows the window, it may be more appropriate to do this in
start(). Or maybe it can be created hidden, and shown in start() ?
> > + if (!sdlScreen_) {
> > + std::cerr << "SDL: could not create window - exiting: " << SDL_GetError() << "\n";
std::endl instead of "\n".
> > + return -1;
>
> is an errno more appropriate?
> Same for the others..
>
> > + }
> > +
> > + sdlRenderer_ = SDL_CreateRenderer(
> > + sdlScreen_, -1, 0);
> > + if (!sdlRenderer_) {
> > + std::cerr << "SDL_CreateRenderer Error\n";
> > + return -2;
Is there a need to clean previous steps when an error occurs, or is
SDL_Quit() enough ? We aim to have no memory leak reported by valgrind
at program exit.
> > + }
> > +
> > + SDL_RenderSetLogicalSize(sdlRenderer_, sCfg.size.width,
> > + sCfg.size.height);
> > +
> > + SDL_PixelFormatEnum pf = (SDL_PixelFormatEnum)sCfg.pixelFormat.fourcc();
> > + if (pf == SDL_DEFINE_PIXELFOURCC('Y', 'U', 'Y', 'V')) {
Please don't assign and test in the same statement.
> > + pf = SDL_PIXELFORMAT_YUY2;
> > + }
>
> Is this some sort of conversion that most fourccs are compatible
> 'except' YUY2? I'd be wary if there is even a single difference, and
> it might be better to put in an explicit conversion table or map?
>
> Particularly as libcamera fourcc's are based on DRM fourccs... are SDL
> fourcc's defined as directly compatible there? I.e. there are frequently
> differences in byte ordering on the RGB/BGR formats that cause issues.
>
> > +
> > + if (!(ret = strcmp(SDL_GetPixelFormatName(pf), "SDL_PIXELFORMAT_UNKNOWN"))) {
No need to assign to ret.
> > + std::cerr << "error: SDL_PIXELFORMAT_UNKNOWN, no " << sCfg.pixelFormat.toString() << " support\n";
> > + return -3;
> > + }
> > +
> > + sdlTexture_ =
> > + SDL_CreateTexture(sdlRenderer_, pf,
> > + SDL_TEXTUREACCESS_STREAMING, sCfg.size.width,
> > + sCfg.size.height);
> > + sdlRect_.w = sCfg.size.width;
> > + sdlRect_.h = sCfg.size.height;
> > +
> > + return 0;
> > +}
> > +
> > +void SDLSink::mapBuffer(FrameBuffer *buffer)
> > +{
> > + std::unique_ptr<Image> image =
> > + Image::fromFrameBuffer(buffer, Image::MapMode::ReadOnly);
> > + assert(image != nullptr);
> > +
> > + mappedBuffers_[buffer] = std::move(image);
> > +}
> > +
> > +bool SDLSink::processRequest(Request *request)
> > +{
> > + for (auto [stream, buffer] : request->buffers())
> > + writeBuffer(buffer);
> > +
> > + return true;
> > +}
> > +
> > +void SDLSink::writeBuffer(FrameBuffer *buffer)
> > +{
> > + Image *image = mappedBuffers_[buffer].get();
> > +
> > + for (unsigned int i = 0; i < buffer->planes().size(); ++i) {
> > + const FrameMetadata::Plane &meta = buffer->metadata().planes()[i];
> > +
> > + Span<uint8_t> data = image->data(i);
> > + if (meta.bytesused > data.size())
> > + std::cerr << "payload size " << meta.bytesused
> > + << " larger than plane size " << data.size()
> > + << std::endl;
> > +
> > + SDL_UpdateTexture(sdlTexture_, &sdlRect_, data.data(), sdlRect_.w * 2);
Does this cause a copy ? If so, is there a zero-copy option ?
> > + SDL_RenderClear(sdlRenderer_);
> > + SDL_RenderCopy(sdlRenderer_, sdlTexture_, NULL, NULL);
> > + SDL_RenderPresent(sdlRenderer_);
> > + SDL_Event e;
> > + while (SDL_PollEvent(&e)) {
> > + if (e.type == SDL_QUIT) { // click close icon then quit
> > + kill(getpid(), SIGINT);
> > + }
> > + };
>
> This seems like an odd place to be doing the event loop polling. I guess
> it's intentional to be able to 'hook' it in somewhere?
>
> I'd be tempted to pull it out to a separate function at least.
It would be nice to integrate that with the main event loop.
> Having never looked at SDL code before, I must say, - that looks like
> it's really quite easy to pull together a window and display!
>
> > + }
> > +}
> > diff --git a/src/cam/sdl_sink.h b/src/cam/sdl_sink.h
> > new file mode 100644
> > index 00000000..f4f843fa
> > --- /dev/null
> > +++ b/src/cam/sdl_sink.h
> > @@ -0,0 +1,40 @@
> > +/* SPDX-License-Identifier: GPL-2.0-or-later */
> > +/*
> > + * sdl_sink.h - SDL Sink
> > + */
> > +
> > +#pragma once
> > +
> > +#include <map>
> > +#include <memory>
> > +#include <string>
> > +
> > +#include <libcamera/stream.h>
> > +
> > +#include <SDL2/SDL.h>
> > +
> > +#include "frame_sink.h"
> > +
> > +class Image;
> > +
> > +class SDLSink : public FrameSink
> > +{
> > +public:
> > + SDLSink();
> > + ~SDLSink();
> > +
> > + int configure(const libcamera::CameraConfiguration &cfg) override;
> > +
> > + void mapBuffer(libcamera::FrameBuffer *buffer) override;
> > +
> > + bool processRequest(libcamera::Request *request) override;
> > +
> > +private:
> > + void writeBuffer(libcamera::FrameBuffer *buffer);
> > +
> > + std::map<libcamera::FrameBuffer *, std::unique_ptr<Image>> mappedBuffers_;
> > + SDL_Window *sdlScreen_;
> > + SDL_Renderer *sdlRenderer_;
> > + SDL_Texture *sdlTexture_;
> > + SDL_Rect sdlRect_;
> > +};
--
Regards,
Laurent Pinchart
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