Added support for hardware-accelerated decoding

config/usb_cam.yml

@@ -30,7 +30,27 @@ camera_transport_suffix: image_raw  # Suffix used by image_transport to generate
 camera_info_url: ""                 # URI for camera calibration data (likely a YML file obtained from camera_calibration)
 image_width: 640                    # Frame dimensions, should be supported by camera hardware
 image_height: 480
-framerate: 30                       # Camera polling frequency, Hz (integer)
+framerate: 10                       # Camera polling frequency, Hz (integer)
+
+# Hardware accelerated decoding (available only for FFMPEG-decoded pixel formats, especially for h264)
+    # The feature is supported only from libavcodec 52.00.100 built with --enable-vdpau --enable-cuvid --enable-nvenc or
+    # --enable-cuda options or any other options activating HWACCEL API like --enable-libdrm. 
+    # The exact list of the available hardware accelerators can be printed with command:
+    # ffmpeg -hwaccels
+    # then the obtained names would be used to activate the decoder.
+    # Known accelerators:
+    # - cuda - for any kind of CUDA/NVENC nVidia-powered accelerators
+    # - vdpau - libvdpau, nVidia PureVideo HD or AMD VCE on selected devices (mostly incompatible with 
+    #   modern H.264 hardware encoders, but decodes almost any flavour of MotionJPEG streams)
+    # - drm - libdrm, Direct Object Rendering on ARM Mali GPUs supporting OpenCL
+    # - nvdec - nVidia Codec SDK for AV1 on compatible GPU
+    # - dxva2 - DirectX Video Accelerator API for Windows
+    # - vaapi - Intel QuickSync or AMD UVD/VCE decoder on compatible Intel chipsets or AMD Radeon GPUs
+    # If the desired accelerated decoder is not available or FFMPEG does not respond correctly on the activation request,
+    # the node falls back automatically to the default software decoder.
+hardware_decoder:
+    enable: false                   # Instructs the node to try to use a hardware-accelerated video decoder
+    name: cuda                      # Name of the desired decoder from FFMPEG HWACCEL API
 
 # Auxiliary camera parameters provided by libv4l2.
     # Names for these parameters are generated automatically according to the intrinsic control names exported by the

include/usb_cam/camera_driver.h

@@ -1,6 +1,7 @@
 #ifndef USB_CAM_CAMERA_DRIVER_H
 #define USB_CAM_CAMERA_DRIVER_H
 
+#include "libavutil/pixfmt.h"
 #include <string>
 #include <iostream>
 #include <algorithm>
@@ -18,6 +19,7 @@ extern "C"
 #include <libavutil/imgutils.h>
 #include <libavutil/frame.h>
 #include <libavutil/mem.h>
+#include <libavutil/hwcontext.h>
 }
 
 #include <fcntl.h>  // for O_* constants
@@ -65,6 +67,17 @@ class AbstractV4LUSBCam
     static camera_image_t * image;
     static bool capturing;
     static std::vector<capture_format_t> supported_formats;
+    // Hardware decoder
+    static bool use_hardware_decoder;
+    static AVHWDeviceType hardware_decoder_type;
+    static std::string hardware_decoder_name;
+    static const AVCodecHWConfig* hardware_decoder_config;
+    static AVPixelFormat hardware_pixel_format;
+    static AVBufferRef* hardware_device_context;
+    static std::vector<std::string> supported_hardware_decoders;
+    static struct SwsContext* hardware_sws;
+    static enum AVPixelFormat get_hardware_pixel_format(AVCodecContext *ctx,
+                                                        const enum AVPixelFormat *pix_fmts);
 
     /* V4L camera parameters */
     static bool streaming_status;
@@ -95,6 +108,7 @@ class AbstractV4LUSBCam
     static bool init();
     static bool start();
     static bool init_decoder();
+    static bool init_hardware_decoder();
     static void run_grabber(unsigned int& buffer_size);
     static bool set_v4l_parameter(const std::string & param, const std::string & value);
     static inline bool set_v4l_parameter(const std::string & param, int value){return set_v4l_parameter(param, std::to_string(value));}
@@ -115,6 +129,7 @@ class AbstractV4LUSBCam
 public:
     virtual ~AbstractV4LUSBCam();
     static std::vector<capture_format_t>& get_supported_formats();
+    static std::vector<std::string>& get_supported_hardware_decoders();
 };
 
 } // namespace usb_cam

include/usb_cam/usb_cam.h

@@ -37,6 +37,7 @@
 #define USB_CAM_USB_CAM_H
 
 #include <ros/forwards.h>
+#include "ros/service_server.h"
 #include "usb_cam/camera_driver.h"
 
 #include <ros/ros.h>
@@ -95,6 +96,11 @@ class UsbCam: public AbstractV4LUSBCam
     static bool service_supported_controls_callback(std_srvs::Trigger::Request& request,
                                                     std_srvs::Trigger::Response& response);
 
+    ros::ServiceServer _service_supported_hardware_decoders;
+    static ros::ServiceServer* service_supported_hardware_decoders;
+    static bool service_supported_hardware_decoders_callback(std_srvs::Trigger::Request& request,
+                                                             std_srvs::Trigger::Response& response);
+
     /* Node parameters */
     static std::string camera_name;
     static std::string camera_frame_id;