CM OPUS Decode

The cmOpusDecode is used to decode the audio/x-opus data to audio/x-raw(PCM) data by the OPUS library.

API Instructions

create/destroy

gpointer cm_opus_decode_create();
void cm_opus_decode_destroy(gpointer hd);

start/stop

void cm_opus_decode_start(gpointer hd);
void cm_opus_decode_stop(gpointer hd);

parameters

Set the opus decode option. The default rate of the output data is 48000hz, if need other formats, set the caps str1 that decode supports.

/* @caps_str0 The input fomat, "audio/x-opus,channel-mapping-family=0,..." */
void cm_opus_decode_set_caps_str0(gpointer hd, const gchar* caps_str0);

/* @caps_str1 The output fomat, "audio/x-raw,rate=x,..." */
void cm_opus_decode_set_caps_str1(gpointer hd, const gchar* caps_str1);

/* @return The output format, "audio/x-raw,..." */
const char* cm_opus_decode_get_caps_str(gpointer had);

/*The decode parse the audio/x-raw media information done*/
gboolean cm_opus_decode_is_ready(gpointer hd);

data

Use the way 1 or way 2 to input opus data.

// data input way 1, push buffer directly /
/* @buffer Opus buffer */
gboolean cm_opus_decode_push_buffer(gpointer hd, GstBuffer *buffer);

// data input way 2, link to source to get data //
/* @src An audio/x-raw source(cmAlsaSrc, ...) */
void cm_opus_encode_link_to_source(gpointer hd, gpointer src);
void cm_opus_encode_unlink(gpointer hd);

/* @ cb data callback to get data */
void cm_opus_encode_set_data_callback(gpointerhd, cm_data_cb_ptrcb, gpointeruser_data);
void cm_opus_encode_remove_data_callback(gpointerhd, cm_data_cb_ptrcb, gpointeruser_data);

others

GstElement* cm_opus_decode_get_bin(gpointer hd);

Demo

Opus PV to PB Demo

Structure

Get opus data and decode it to PCM data.

Main codes

static GstFlowReturn _out_data_cb (GstBuffer *buffer, gpointer user_data) {
    ......
	return GST_FLOW_OK;
}

static int idx = 0;
static gboolean stop = FALSE;
static gboolean _opus_feed_loop(gpointer arg){

	if(opus_dec && !stop){

		GstBuffer *buffer = NULL;

		if(input){
			char name[16] = {0};

			sprintf(name, input, idx++);
			FILE *fd = fopen(name, "rb");
			gst_print("open %s\n", name);
			
			if(fd){
				char data[256] = {0};
				int len = fread(data, 1, 256, fd);
				fclose(fd);

                //data from file
				buffer = gst_buffer_new_allocate (NULL, len, NULL);
			    gst_buffer_fill(buffer, 0, data, len);

			}
			else{
				gst_print("read end\n");
				
				idx = 0;

				stop = TRUE;
			}
		}
		else{
            //data from cache
			buffer = gst_buffer_new_allocate (NULL, opus_frame_size, NULL);
			gst_buffer_fill(buffer, 0, opus_frame_data, opus_frame_size);
		}

		if(buffer){
            //Set PTS and DTS
			GST_BUFFER_PTS(buffer) = gst_util_get_timestamp();
			GST_BUFFER_DTS(buffer) = GST_BUFFER_PTS(buffer);

			//gst_buffer_info_dump(buffer, "OPUS_DEC", FALSE);

            //Push data to decode
			cm_opus_decode_push_buffer(opus_dec, buffer);

		    gst_buffer_unref(buffer);
		}
	}

	return TRUE;
}

static gboolean _main_loop(gpointer arg) {

	if(!opus_dec){
        //Create decode
		opus_dec = cm_opus_decode_create();
        //Set output call back
		cm_opus_decode_set_data_callback(opus_dec , _out_data_cb, opus_dec);
    	//Start
        cm_opus_decode_start(opus_dec);

		stop = FALSE;
	}
    ......
	return TRUE;
}

For more details please refer to the demo file.
Test result

The PCM data can be played on the PC.