moonlight-common-c/limelight-common/SdpGenerator.c

#include "Limelight-internal.h"

#define MAX_OPTION_NAME_LEN 128

#define MAX_SDP_HEADER_LEN 128
#define MAX_SDP_TAIL_LEN 128

#define RTSP_CLIENT_VERSION_S "10"

typedef struct _SDP_OPTION {
	char name[MAX_OPTION_NAME_LEN+1];
	void* payload;
	int payloadLen;
	struct _SDP_OPTION *next;
} SDP_OPTION, *PSDP_OPTION;

/* Cleanup the attribute list */
static void freeAttributeList(PSDP_OPTION head) {
	PSDP_OPTION next;
	while (head != NULL) {
		next = head->next;
		free(head);
		head = next;
	}
}

/* Get the size of the attribute list */
static int getSerializedAttributeListSize(PSDP_OPTION head) {
	PSDP_OPTION currentEntry = head;
	int size = 0;
	while (currentEntry != NULL) {
		size += strlen("a=");
		size += strlen(currentEntry->name);
		size += strlen(":");
		size += currentEntry->payloadLen;
		size += strlen(" \r\n");

		currentEntry = currentEntry->next;
	}
	return size;
}

/* Populate the serialized attribute list into a string */
static int fillSerializedAttributeList(char* buffer, PSDP_OPTION head) {
	PSDP_OPTION currentEntry = head;
	int offset = 0;
	while (currentEntry != NULL) {
		offset += sprintf(&buffer[offset], "a=%s:", currentEntry->name);
		memcpy(&buffer[offset], currentEntry->payload, currentEntry->payloadLen);
		offset += currentEntry->payloadLen;
		offset += sprintf(&buffer[offset], " \r\n");

		currentEntry = currentEntry->next;
	}
	return offset;
}

/* Add an attribute */
static int addAttributeBinary(PSDP_OPTION *head, char* name, const void* payload, int payloadLen) {
	PSDP_OPTION option, currentOption;

	option = malloc(sizeof(*option) + payloadLen);
	if (option == NULL) {
		return -1;
	}

	option->next = NULL;
	option->payloadLen = payloadLen;
	strcpy(option->name, name);
	option->payload = (void*)(option + 1);
	memcpy(option->payload, payload, payloadLen);

	if (*head == NULL) {
		*head = option;
	}
	else {
		currentOption = *head;
		while (currentOption->next != NULL) {
			currentOption = currentOption->next;
		}
		currentOption->next = option;
	}

	return 0;
}

/* Add an attribute string */
static int addAttributeString(PSDP_OPTION *head, char* name, const char* payload) {
	// We purposefully omit the null terminating character
	return addAttributeBinary(head, name, payload, (int)strlen(payload));
}

static PSDP_OPTION getAttributesList(PSTREAM_CONFIGURATION streamConfig, struct in_addr targetAddress) {
	PSDP_OPTION optionHead;
	int payloadInt;
	char payloadStr[64];
	int err;

	optionHead = NULL;

	err = 0;
	err |= addAttributeString(&optionHead, "x-nv-general.serverAddress",
		inet_ntoa(targetAddress));

	payloadInt = htonl(0x42774141);
	err |= addAttributeBinary(&optionHead,
		"x-nv-general.featureFlags", &payloadInt, sizeof(payloadInt));

	sprintf(payloadStr, "%d", streamConfig->width);
	err |= addAttributeString(&optionHead, "x-nv-video[0].clientViewportWd", payloadStr);
	sprintf(payloadStr, "%d", streamConfig->height);
	err |= addAttributeString(&optionHead, "x-nv-video[0].clientViewportHt", payloadStr);

	sprintf(payloadStr, "%d", streamConfig->fps);
	err |= addAttributeString(&optionHead, "x-nv-video[0].maxFPS", payloadStr);

	payloadInt = htonl(0x41514141);
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[0].transferProtocol", &payloadInt, sizeof(payloadInt));
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[1].transferProtocol", &payloadInt, sizeof(payloadInt));
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[2].transferProtocol", &payloadInt, sizeof(payloadInt));
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[3].transferProtocol", &payloadInt, sizeof(payloadInt));

	payloadInt = htonl(0x42414141);
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[0].rateControlMode", &payloadInt, sizeof(payloadInt));
	payloadInt = htonl(0x42514141);
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[1].rateControlMode", &payloadInt, sizeof(payloadInt));
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[2].rateControlMode", &payloadInt, sizeof(payloadInt));
	err |= addAttributeBinary(&optionHead,
		"x-nv-video[3].rateControlMode", &payloadInt, sizeof(payloadInt));

	err |= addAttributeString(&optionHead, "x-nv-video[0].timeoutLengthMs", "7000");
	err |= addAttributeString(&optionHead, "x-nv-video[0].framesWithInvalidRefThreshold", "0");
	
	// FIXME: This number is taken from limelight-common, but doesn't have the same
	// bitrate floor which can cause blockiness when scaling
	err |= addAttributeString(&optionHead, "x-nv-vqos[0].bw.flags", "14083");

	sprintf(payloadStr, "%d", streamConfig->bitrate);
	err |= addAttributeString(&optionHead, "x-nv-vqos[0].bw.maximumBitrate", payloadStr);

    // Using FEC turns padding on which makes us have to take the slow path
    // in the depacketizer, not to mention exposing some ambiguous cases with
    // distinguishing padding from valid sequences. Since we can only perform
    // execute an FEC recovery on a 1 packet frame, we'll just turn it off completely.
    err |= addAttributeString(&optionHead, "x-nv-vqos[0].fec.enable", "0");

	err |= addAttributeString(&optionHead, "x-nv-vqos[0].videoQualityScoreUpdateTime", "5000");
	err |= addAttributeString(&optionHead, "x-nv-vqos[0].qosTrafficType", "5");

	err |= addAttributeString(&optionHead, "x-nv-vqos[0].videoQosMaxConsecutiveDrops", "0");
	err |= addAttributeString(&optionHead, "x-nv-vqos[1].videoQosMaxConsecutiveDrops", "0");
	err |= addAttributeString(&optionHead, "x-nv-vqos[2].videoQosMaxConsecutiveDrops", "0");
	err |= addAttributeString(&optionHead, "x-nv-vqos[3].videoQosMaxConsecutiveDrops", "0");

	err |= addAttributeString(&optionHead, "x-nv-aqos.qosTrafficType", "8");

	if (err == 0) {
		return optionHead;
	}

	freeAttributeList(optionHead);
	return NULL;
}

/* Populate the SDP header with required information */
static int fillSdpHeader(char* buffer, struct in_addr targetAddress) {
	return sprintf(buffer,
		"v=0\r\n"
		"o=android 0 "RTSP_CLIENT_VERSION_S" IN IPv4 %s\r\n"
		"s=NVIDIA Streaming Client\r\n", inet_ntoa(targetAddress));
}

/* Populate the SDP tail with required information */
static int fillSdpTail(char* buffer) {
	return sprintf(buffer,
		"t=0 0\r\n"
		"m=video 47996  \r\n");
}

/* Get the SDP attributes for the stream config */
char* getSdpPayloadForStreamConfig(PSTREAM_CONFIGURATION streamConfig, struct in_addr targetAddress, int *length) {
	PSDP_OPTION attributeList;
	int offset;
	char* payload;

	attributeList = getAttributesList(streamConfig, targetAddress);
	if (attributeList == NULL) {
		return NULL;
	}

	payload = malloc(MAX_SDP_HEADER_LEN + MAX_SDP_TAIL_LEN +
		getSerializedAttributeListSize(attributeList));
	if (payload == NULL) {
		freeAttributeList(attributeList);
		return NULL;
	}

	offset = fillSdpHeader(payload, targetAddress);
	offset += fillSerializedAttributeList(&payload[offset], attributeList);
	offset += fillSdpTail(&payload[offset]);

	freeAttributeList(attributeList);
	*length = offset;
	return payload;
}