1 files changed, 92 insertions, 15 deletions

diff --git a/v4l2-apps/libv4l/libv4l2/libv4l2.c b/v4l2-apps/libv4l/libv4l2/libv4l2.c
index b7e9ae7c4..07bd9484e 100644
--- a/v4l2-apps/libv4l/libv4l2/libv4l2.c
+++ b/v4l2-apps/libv4l/libv4l2/libv4l2.c
@@ -77,6 +77,7 @@
 #define V4L2_SUPPORTS_READ		0x0800
 #define V4L2_IS_UVC			0x1000
 #define V4L2_STREAM_TOUCHED		0x2000
+#define V4L2_USE_READ_FOR_READ		0x4000
 
 #define V4L2_MMAP_OFFSET_MAGIC      0xABCDEF00u
 
@@ -101,7 +102,7 @@ static int v4l2_request_read_buffers(int index)
   req.memory = V4L2_MEMORY_MMAP;
   if ((result = SYS_IOCTL(devices[index].fd, VIDIOC_REQBUFS, &req)) < 0){
     int saved_err = errno;
-    V4L2_LOG_ERR("requesting %u buffers: %s\n", req.count, strerror(errno));
+    V4L2_LOG("warning reqbuf (%u) failed: %s\n", req.count, strerror(errno));
     errno = saved_err;
     return result;
   }
@@ -305,6 +306,63 @@ static int v4l2_dequeue_and_convert(int index, struct v4l2_buffer *buf,
   return result;
 }
 
+static int v4l2_read_and_convert(int index, unsigned char *dest, int dest_size)
+{
+  const int max_tries = 10;
+  int result, buf_size, tries = max_tries;
+
+  buf_size = devices[index].dest_fmt.fmt.pix.sizeimage;
+  buf_size = (buf_size + 8191) & ~8191;
+
+  if (devices[index].readbuf_size < buf_size) {
+    unsigned char *new_buf;
+
+    new_buf = realloc(devices[index].readbuf, buf_size);
+    if (!new_buf)
+      return -1;
+
+    devices[index].readbuf = new_buf;
+    devices[index].readbuf_size = buf_size;
+  }
+
+  do {
+    result = SYS_READ(devices[index].fd, devices[index].readbuf, buf_size);
+    if (result <= 0) {
+      if (result && errno != EAGAIN) {
+	int saved_err = errno;
+	V4L2_LOG_ERR("reading: %s\n", strerror(errno));
+	errno = saved_err;
+      }
+      return result;
+    }
+
+    result = v4lconvert_convert(devices[index].convert,
+	   &devices[index].src_fmt, &devices[index].dest_fmt,
+	   devices[index].readbuf, result, dest, dest_size);
+
+    if (result < 0) {
+      int saved_err = errno;
+
+      if(errno == EAGAIN)
+	V4L2_LOG("warning error while converting frame data: %s\n",
+	  v4lconvert_get_error_message(devices[index].convert));
+      else
+	V4L2_LOG_ERR("converting / decoding frame data: %s\n",
+	  v4lconvert_get_error_message(devices[index].convert));
+
+      errno = saved_err;
+    }
+    tries--;
+  } while (result < 0 && errno == EAGAIN && tries);
+
+  if (result < 0 && errno == EAGAIN) {
+    V4L2_LOG_ERR("got %d consecutive frame decode errors, last error: %s\n",
+      max_tries, v4lconvert_get_error_message(devices[index].convert));
+  }
+
+  return result;
+}
+
 static int v4l2_queue_read_buffers(int index)
 {
   unsigned int i;
@@ -332,6 +390,11 @@ static int v4l2_activate_read_stream(int index)
 {
   int result;
 
+  if ((devices[index].flags & V4L2_STREAMON) || devices[index].frame_queued) {
+    errno = EBUSY;
+    return -1;
+  }
+
   if ((result = v4l2_request_read_buffers(index)))
     return result;
 
@@ -528,6 +591,8 @@ int v4l2_fd_open(int fd, int v4l2_flags)
     devices[index].frame_map_count[i] = 0;
   }
   devices[index].frame_queued = 0;
+  devices[index].readbuf = NULL;
+  devices[index].readbuf_size = 0;
 
   if (index >= devices_used)
     devices_used = index + 1;
@@ -585,6 +650,9 @@ int v4l2_close(int fd)
     devices[index].convert_mmap_buf = MAP_FAILED;
   }
   v4lconvert_destroy(devices[index].convert);
+  free(devices[index].readbuf);
+  devices[index].readbuf = NULL;
+  devices[index].readbuf_size = 0;
 
   /* Remove the fd from our list of managed fds before closing it, because as
      soon as we've done the actual close the fd maybe returned by an open in
@@ -1070,7 +1138,6 @@ ssize_t v4l2_read (int fd, void* dest, size_t n)
 {
   ssize_t result;
   int index;
-  struct v4l2_buffer buf;
 
   if ((index = v4l2_get_index(fd)) == -1)
     return SYS_READ(fd, dest, n);
@@ -1085,23 +1152,33 @@ ssize_t v4l2_read (int fd, void* dest, size_t n)
     goto leave;
   }
 
-  if (!(devices[index].flags & V4L2_STREAM_CONTROLLED_BY_READ)) {
-    if ((devices[index].flags & V4L2_STREAMON) ||
-	devices[index].frame_queued) {
-      errno = EBUSY;
-      result = -1;
-      goto leave;
-    }
+  /* Since we need to do conversion try to use mmap (streaming) mode under
+     the hood as that safes a memcpy for each frame read.
+
+     Note sometimes this will fail as some drivers (atleast gspca) do not allow
+     switching from read mode to mmap mode and they assume read() mode if a
+     select or poll() is done before any buffers are requested. So using mmap
+     mode under the hood will fail if a select() or poll() is done before the
+     first emulated read() call. */
+  if (!(devices[index].flags & V4L2_STREAM_CONTROLLED_BY_READ) &&
+      !(devices[index].flags & V4L2_USE_READ_FOR_READ)) {
     if ((result = v4l2_activate_read_stream(index)))
-      goto leave;
+      /* Activating mmap mode failed, use read() instead */
+      devices[index].flags |= V4L2_USE_READ_FOR_READ;
   }
 
-  buf.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE;
-  buf.memory = V4L2_MEMORY_MMAP;
-  result = v4l2_dequeue_and_convert(index, &buf, dest, n);
+  if (devices[index].flags & V4L2_USE_READ_FOR_READ) {
+    result = v4l2_read_and_convert(index, dest, n);
+  } else {
+    struct v4l2_buffer buf;
 
-  if (result >= 0)
-    v4l2_queue_read_buffer(index, buf.index);
+    buf.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    buf.memory = V4L2_MEMORY_MMAP;
+    result = v4l2_dequeue_and_convert(index, &buf, dest, n);
+
+    if (result >= 0)
+      v4l2_queue_read_buffer(index, buf.index);
+  }
 
 leave:
   pthread_mutex_unlock(&devices[index].stream_lock);