simaaidecoder

The simaaidecoder GStreamer plugin is a video decoder that supports H.264 and H.265 decoding. It integrates with SiMa.ai hardware for efficient video processing. The plugin outputs video frames in either NV12 or YUV420P format.

Properties

The following properties can be configured for the simaaidecoder plugin:

Property Name	Type	Default Value	Description
dec-width	int	0	Video file resolution width.
dec-height	int	0	Video file resolution height.
drop-threshold	int	1800	Number of consecutive out-of-size frames before posting an MQTT message (requires external MQTT setup).
drop-on-resolution-change	boolean	FALSE	When TRUE, any resolution change is dropped immediately.
dec-fps	int	0	Frames per second (FPS) control. Works only for dec-mode: split-input mode.
dec-ip-cnt	int	2 (unalign), 5 (split)	Decoder input buffer count. Default is 2 for unalign-input mode and 5 for split-input mode.
op-pool-cnt	int	30	Plugin output buffer count from the pool, as specified in the next-element property.
ip-queue-max-buffers	int	60	High watermark for the input queue; if exceeded, it blocks.
ip-queue-min-buffers	int	30	Low watermark for the input queue.
dec-type	string	h264	Decoder type: either “h264” or “h265”.
dec-mode	string	split-input	Decoder input mode: either “split-input” or “unalign-input”.
next-element	string	CVU	Consumer of output: Choose one of “CVU”, “FPGA”, “ISP”, “APU” (currently only CVU and APU are supported).
apu-mem-pool	string	malloc	A65 memory pool (works if next-element is APU): Choose “malloc” or “CMA(reserved)”.
dec-fmt	string	NV12	Output YUV format: either “NV12” or “YUV420P”.
dump-cnt	int	0	Number of decoded frames to be dumped to the specified path.
dump-path	string	/tmp	Path for decoded frames to be dumped.
memory-opt	boolean	FALSE	Optimize internal memory buffers. Note that this impacts performance; recommended only for multi-channels.
sima-allocator-type	int	1	Type of SiMa allocator to use: 1 - no segment API, 2 - segment API support.
op-buff-name	string	simaaidecoder0	Output buffer name as a custom meta for output buffer (Default: plugin name, if no CM element-name is present)
op-buff-cached	boolean	TRUE	Specify if output buffers from the decoder are cached (applicable for CVU & CMA heap).
transmit	boolean	FALSE	Transmit KPI messages.

Usage

The simaaidecoder plugin is integrated into a GStreamer pipeline like this:

gst-launch-1.0 filesrc location=input.mp4 ! h264parse ! simaaidecoder ! videoconvert ! autovideosink

Replace input.mp4 with the actual path to your H.264 video file. For H.265, use h265parse instead of h264parse. You can adjust properties using the simaaidecoder plugin’s properties as needed (e.g., simaaidecoder dec-width=1280 dec-height=720).

Installation

To install the simaaidecoder plugin, copy the plugin files from /usr/local/simaai/plugin_zoo/gst-simaai-plugins-base/gst/ into your project’s plugins/ directory.

Integration into a GStreamer Pipeline

The simaaidecoder plugin takes encoded video data (H.264 or H.265) as input on its sink pad and outputs decoded raw video data (NV12 or YUV420P) on its source pad. It’s essential to place appropriate upstream elements (e.g., filesrc, h264parse, h265parse) to provide encoded data and downstream elements (e.g., videoconvert, autovideosink) to process the decoded output. The plugin leverages SiMa.ai libraries for hardware-accelerated decoding.