CM H264 Encode

The cmH264Encode is used to encode the video/x-raw(YUV) data to video/h264(H264) data by the gstvideo4linux2 library. It uses a hardware encoder on the C3V.

API Instructions

create/destroy

gpointer cm_h264_encode_create();
void cm_h264_encode_destroy(gpointer hd);

start/stop

void cm_h264_encode_start(gpointer hd);
void cm_h264_encode_stop(gpointer hd);

parameters

The h264 encoder parameters:

/* @ gop_size The GOP size for IPPP*/
void cm_h264_encode_set_gop_size(gpointer hd, int gop_size);
/* 
 * Variable bitrate control 
 * @qpmin qp minium, >= 0
 * @qpmax qp maximum, <=51
 * @br_max max bitrate
 */
void cm_h264_encode_set_bitrate_vbr(gpointer hd, int qpmin, int qpmax, int br_max);
/* @br Constant bitreate control value */
void cm_h264_encode_set_bitrate_cbr(gpointer hd, int be);
/* @qp Constant qp value */
void cm_h264_encode_set_bitrate_cq(gpointer hd, int qp);
/* Start keyframe encode immediately*/
void cm_h264_encode_set_froce_key_frame(gpointer hd);

Get the h264 media info with caps string format.

/* @return Encode output format, "video/h264,......" */
const char* cm_h264_encode_get_caps_str(gpointer hd);

data

The encoder needs to know the actual format of the input before encoding, so must ensure the source is ready to be linked(the media info is ready).

/* @src A video/x-raw source(cmV4l2Src, ...) */
void cm_h264_encode_link_to_source(gpointer hd, gpointer src);
void cm_h264_encode_unlink(gpointer hd);

/* @ cb data callback to get 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);

Demo

H264 Encode Demo

Structure

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

Main codes

//The h264 data will be send to here
static GstFlowReturn _out_data_cb (GstBuffer *buffer, gpointer user_data) {

	......

	return GST_FLOW_OK;
}

static gboolean _main_loop(gpointer arg) {
	if(!yuv_hd) {
		yuv_hd = cm_video_v4l2_source_create("/dev/video0");
        //Choose the data format
		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);
	}
    //Wait the source is ready to be linked
	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);
	}

    ......

	return TRUE;
}

For more details please refer to the demo file.

Test result

The h264 data can be saved to the file and displayed on the PC.

C3V Documentation

CM H264 Encode

API Instructions

Demo

H264 Encode Demo

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