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/* Copyright 2016 Luke Shumaker */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "mpjpeg.h"
#include "util.h"
#define STARTS_WITH(str, prefix) strncmp(str, prefix, sizeof(prefix)-1)
static
char *boundary_line(const char *old) {
size_t len = strlen(old);
char *new = xrealloc(NULL, len+5);
new[0] = '-';
new[1] = '-';
strcpy(&new[2], old);
new[2+len+0] = '\r';
new[2+len+1] = '\n';
new[2+len+2] = '\0';
return new;
}
void mpjpeg_reader(struct mpjpeg_stream *s, int fd, const char *boundary) {
FILE *stream = fdopen(fd, "r");
boundary = boundary_line(boundary);
char *line_buf = NULL;
size_t line_cap = 0;
ssize_t line_len = 0;
while (1) {
printf("getting frame\n");
s->back->len = -1;
/* read the frame header (MIME headers) */
line_len = getline(&line_buf, &line_cap, stream);
if (strcmp(line_buf, boundary) != 0)
return;
ssize_t framelen = -1;
while (strcmp(line_buf, "\r\n") != 0 && line_len >= 0) {
line_len = getline(&line_buf, &line_cap, stream);
if (STARTS_WITH(line_buf, "Content-Type:") == 0) {
printf("line: <%s>\n", line_buf);
s->back->len = atoi(&line_buf[strlen("Content-Type:")]);
}
}
if (s->back->len < 0)
return;
/* read the frame contents (JPEG) */
if (s->back->cap < (size_t)s->back->len)
s->back->data = xrealloc(s->back->data, s->back->cap = s->back->len);
if (fread(line_buf, framelen, 1, stream) != 1)
return;
printf("got frame on fd %d\n", fd);
/* swap the frames */
pthread_mutex_lock(&s->frontlock);
struct frame *tmp = s->front;
s->front = s->back;
s->back = tmp;
pthread_mutex_unlock(&s->frontlock);
}
}
void mpjpeg_writer(struct mpjpeg_stream *s, int fd, const char *boundary) {
struct frame myframe = { 0 };
struct frame *lastframe = NULL;
while(1) {
/* get the most recent frame (copy front to myframe) */
pthread_mutex_lock(&s->frontlock);
if (s->front == lastframe) { /* TODO: use a pthread_cond_t instead of a busy loop */
pthread_mutex_unlock(&s->frontlock);
continue;
}
if (myframe.cap < (size_t)s->front->len)
myframe.data = xrealloc(myframe.data, myframe.cap = s->front->len);
memcpy(myframe.data, s->front->data, myframe.len = s->front->len);
lastframe = s->front;
pthread_mutex_unlock(&s->frontlock);
/* send the frame to the client */
if (dprintf(fd, "--%s\r\nContent-Type: image/jpeg\r\nContent-Length: %zd\r\n\r\n", boundary, myframe.len) < 0)
return;
if (write(fd, myframe.data, myframe.len) < myframe.len)
return;
}
}
void init_mpjpeg_stream(struct mpjpeg_stream *s) {
ZERO(s->a);
ZERO(s->b);
s->front = &s->a;
s->back = &s->b;
pthread_mutex_init(&s->frontlock, NULL);
}
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