CM H264 Decode

The cmH264Decode is used to decode the video/h264 data to video/x-raw(YUV) data by the gstvideo4linux2 library. It uses a hardware decode on C3V.

API Instructions

create/destroy

gpointer cm_h264_decode_create();
void cm_h264_decode_destroy(gpointer hd);

start/stop

void cm_h264_decode_start(gpointer hd);
void cm_h264_decode_stop(gpointer hd);

parameters

The h264 decoder parameters:

/* @caps_str0 Decode input format, "video/h264,..." */
void cm_h264_decode_set_caps_str0(gpointer hd, const gchar* caps_str0);

Get the h264 media info with caps string format.

/* @return Decode output format, "video/x-raw,..." */
const char* cm_h264_decode_get_caps_str(gpointer hd);

data

// data input way 1, push the h264 data directly //
/* @buffer H264 buffer */
gboolean cm_h264_decode_push_buffer(gpointer hd, GstBuffer *buffer);

// data input way 2, use source such as cmAppSrc //
/* @src video/h264 src */
void cm_h264_encode_link_to_source(gpointer hd, gpointer src);
void cm_h264_encode_unlink(gpointer hd);

/* @ cb data callback to get video/x-raw data */
void cm_h264_encode_set_data_callback(gpointer hd, cm_data_cb_ptrcb, gpointeruser_data);
void cm_h264_encode_remove_data_callback(gpointer hd, cm_data_cb_ptrcb, gpointeruser_data);

Others

GstElement* cm_h264_decode_get_bin(gpointer hd);
gboolean cm_h264_decode_is_ready(gpointer hd);

Demo

H264 Decode Demo

Structure

Get YUV data from the sensor and encode it to H264, then decode it to YUV.

Main codes

static GstFlowReturn _out_data_cb (GstBuffer *buffer, gpointer user_data) {

    ......

#if USE_H264_DECODE
	if(user_data == h264_hd){
		if(h264_dec){
			//Push h264 data to decode
			cm_h264_decode_push_buffer(h264_dec, buffer);
		}
	}
#endif

	return GST_FLOW_OK;
}

static gboolean _main_loop(gpointer arg) {
	if(!yuv_hd) {
		yuv_hd = cm_video_v4l2_source_create("/dev/video0");
		cm_video_v4l2_source_set_caps_str0(yuv_hd, 
  			"video/x-raw,format=UYVY,width=1280,height=720,colorimetry=(string)1:4:7:1");
		cm_video_v4l2_source_start(yuv_hd);
	}

	if(!h264_hd && cm_video_v4l2_source_is_ready(yuv_hd)){		
		h264_hd = cm_h264_encode_create();

		//Link H264 encode to v4l2 src
	  	cm_h264_encode_link_to_source(h264_hd, yuv_hd);

		//Set callback to get h264 data
	  	cm_h264_encode_set_data_callback(h264_hd, _out_data_cb, h264_hd);
	  	cm_h264_encode_start(h264_hd);
	}

#if USE_H264_DECODE
	if(!h264_dec){
        //Create H264 Decode
		h264_dec = cm_h264_decode_create();
        //Set data callback
		cm_h264_decode_set_data_callback(h264_dec, _out_data_cb, h264_dec);
	  	//Start
        cm_h264_decode_start(h264_dec);
	}
#endif
    
    ......
        
	return TRUE;
}

For more details please refer to the demo file.

Test result

The YUV data can be saved to the file and display on the PC by the tools.

C3V Documentation

CM H264 Decode

API Instructions

Demo

H264 Decode Demo

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