I want to use the sendto() API to send video and audio data through UDP packet. The sending buffer size I got using getsockopt() is 114688, however, sendto() returned -1 when the data packet less than 65536 not 114688. And the error message is Message too long.
When I used setsockopt() to adjust the sending buffer size as 200000, I used getsockopt() and found the sending buffer size was not 200000 but 262142. So I still got the same error when I sent data packet with a size bigger than 65536.
I am confused about this situation. I want to know what the reason is and how to solve this problem.
When I used FFMPEG library to send the video and audio packet, there is no error. So I am sure there is a solution for this problem and I missed something.
Is there anyone can help me about this problem? I really can not understand what the reason is.
The OS I used is ubuntu 11.04,I got the same results in ubuntu 11.10.
That is the code I used to create socket and configure the parameter：
unsigned char *output_buffer = (unsigned char*)av_malloc(IO_BUFFER_SIZE);if (NULL == output_buffer) { printf("Couldn't allocate input buffer.\n"); return NULL;}output_context_data_t *context_data = (output_context_data_t *)malloc(sizeof(output_context_data_t));if (NULL == context_data) { printf("Could not allocate output context data.\n"); av_free(output_buffer); return NULL;}context_data->socket = socket(AF_INET, SOCK_DGRAM, 0);if(context_data->socket < 0) { printf("socket creating fail!\n"); return NULL; }context_data->socket_addr->sin_family = AF_INET;context_data->socket_addr->sin_port = htons(output_port);ret = inet_pton(AF_INET, output_ip, &(context_data->socket_addr->sin_addr));if(0 == ret) { printf("inet_pton fail!\n"); return NULL;}ret = setsockopt(context_data->socket, IPPROTO_IP, IP_MULTICAST_TTL,&option_ttl, sizeof(int));if(ret < 0) { printf("ttl configuration fail!\n"); return NULL;}ret = setsockopt(context_data->socket, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(int));if(ret < 0) { printf("resue configuration fail!\n"); return NULL;} That is the code to send UDP packet：
int send_size = sendto(context_data->socket, buf, buf_size, 0, (struct sockaddr *)context_data->socket_addr, sizeof(*context_data->socket_addr)));//the video or audio data is in buf and its size is buf_size.That is the code I used to get the sending buffer size：
int bufsize; int size = sizeof(bufsize);getsockopt(context_data->socket,SOL_SOCKET, SO_SNDBUF, &bufsize, &size);That is the code I used to configure the sending buffer size：
tmp = 200000;ret = setsockopt(context_data->socket, SOL_SOCKET, SO_SNDBUF, &tmp, sizeof(tmp));if(ret < 0) { printf("sending buffer size configuration fail!\n"); return NULL;}