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v4l2: Cleanup and fix calculation of latency

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Calculation of num_buffers (the max latency in buffers) was
up-side-down.  If we can allcoate, then our maximum latency match
pool maximum number of buffers. Also renamed it to max latency. Finally
introduced a min_latency for clarity.
This commit is contained in:
Nicolas Dufresne 2014-05-24 23:31:24 -04:00
parent 2e89f4ecff
commit 66519d08b0
3 changed files with 39 additions and 42 deletions
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76
sys/v4l2/gstv4l2bufferpool.c
View file

@ -622,7 +622,8 @@ gst_v4l2_buffer_pool_start (GstBufferPool * bpool)
GstStructure *config;
GstCaps *caps;
guint size, min_buffers, max_buffers;
guint num_buffers = 0, copy_threshold = 0;
guint max_latency, min_latency, copy_threshold = 0;
gboolean can_allocate = FALSE;
GST_DEBUG_OBJECT (pool, "activating pool");
@ -631,31 +632,28 @@ gst_v4l2_buffer_pool_start (GstBufferPool * bpool)
&max_buffers))
goto wrong_config;
/* TODO Also consider min_buffers_for_output when implemented */
min_latency = MAX (GST_V4L2_MIN_BUFFERS, obj->min_buffers_for_capture);
switch (obj->mode) {
case GST_V4L2_IO_RW:
/* this value also instructs the latency calculation to have min_buffers
* frame latency max */
num_buffers = min_buffers;
can_allocate = TRUE;
break;
case GST_V4L2_IO_DMABUF:
case GST_V4L2_IO_MMAP:
{
guint count;
if (GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, MMAP)) {
num_buffers = min_buffers;
} else {
num_buffers = max_buffers;
}
can_allocate = GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, MMAP);
/* first, lets request buffers, and see how many we can get: */
GST_DEBUG_OBJECT (pool, "requesting %d MMAP buffers", num_buffers);
GST_DEBUG_OBJECT (pool, "requesting %d MMAP buffers", min_buffers);
count = gst_v4l2_allocator_start (pool->vallocator, num_buffers,
count = gst_v4l2_allocator_start (pool->vallocator, min_buffers,
V4L2_MEMORY_MMAP);
if (count < GST_V4L2_MIN_BUFFERS) {
num_buffers = count;
min_buffers = count;
goto no_buffers;
}
@ -664,12 +662,11 @@ gst_v4l2_buffer_pool_start (GstBufferPool * bpool)
* falling back to copy if the pipeline needed more buffers. This also
* prevent having to do REQBUFS(N)/REQBUFS(0) everytime configure is
* called. */
if (count != num_buffers) {
if (count != min_buffers) {
GST_WARNING_OBJECT (pool, "using %u buffers instead of %u",
count, num_buffers);
num_buffers = count;
copy_threshold =
MAX (GST_V4L2_MIN_BUFFERS, obj->min_buffers_for_capture);
count, min_buffers);
min_buffers = count;
copy_threshold = min_latency;
/* The initial minimum could be provide either by GstBufferPool or
* driver needs. */
@ -682,60 +679,59 @@ gst_v4l2_buffer_pool_start (GstBufferPool * bpool)
{
guint count;
if (GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, USERPTR)) {
num_buffers = min_buffers;
} else {
num_buffers = max_buffers;
}
can_allocate =
GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, USERPTR);
GST_DEBUG_OBJECT (pool, "requesting %d USERPTR buffers", num_buffers);
GST_DEBUG_OBJECT (pool, "requesting %d USERPTR buffers", min_buffers);
count = gst_v4l2_allocator_start (pool->vallocator, num_buffers,
count = gst_v4l2_allocator_start (pool->vallocator, min_buffers,
V4L2_MEMORY_USERPTR);
/* There is no rational to not get what we asked */
if (count < num_buffers) {
num_buffers = count;
if (count < min_buffers) {
min_buffers = count;
goto no_buffers;
}
min_buffers = num_buffers = count;
min_buffers = count;
break;
}
case GST_V4L2_IO_DMABUF_IMPORT:
{
guint count;
if (GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, DMABUF)) {
num_buffers = min_buffers;
} else {
num_buffers = max_buffers;
}
can_allocate = GST_V4L2_ALLOCATOR_CAN_ALLOCATE (pool->vallocator, DMABUF);
GST_DEBUG_OBJECT (pool, "requesting %d DMABUF buffers", num_buffers);
GST_DEBUG_OBJECT (pool, "requesting %d DMABUF buffers", min_buffers);
count = gst_v4l2_allocator_start (pool->vallocator, num_buffers,
count = gst_v4l2_allocator_start (pool->vallocator, min_buffers,
V4L2_MEMORY_DMABUF);
/* There is no rational to not get what we asked */
if (count < num_buffers) {
num_buffers = count;
if (count < min_buffers) {
min_buffers = count;
goto no_buffers;
}
min_buffers = num_buffers = count;
min_buffers = count;
break;
}
default:
num_buffers = 0;
min_buffers = 0;
copy_threshold = 0;
g_assert_not_reached ();
break;
}
if (can_allocate)
max_latency = max_buffers;
else
max_latency = min_buffers;
pool->size = size;
pool->copy_threshold = copy_threshold;
pool->num_buffers = num_buffers;
pool->max_latency = max_latency;
pool->min_latency = min_latency;
pool->num_queued = 0;
if (max_buffers < min_buffers)
@ -780,7 +776,7 @@ no_buffers:
{
GST_ERROR_OBJECT (pool,
"we received %d buffer from device '%s', we want at least %d",
num_buffers, obj->videodev, GST_V4L2_MIN_BUFFERS);
min_buffers, obj->videodev, GST_V4L2_MIN_BUFFERS);
gst_structure_free (config);
return FALSE;
}

3
sys/v4l2/gstv4l2bufferpool.h
View file

@ -60,7 +60,8 @@ struct _GstV4l2BufferPool
gboolean add_videometa; /* set if video meta should be added */
guint num_buffers; /* number of buffers we use */
guint min_latency; /* number of buffers we will hold */
guint max_latency; /* number of buffers we can hold */
guint num_queued; /* number of buffers queued in the driver */
guint copy_threshold; /* when our pool runs lower, start handing out copies */

2
sys/v4l2/gstv4l2src.c
View file

@ -505,7 +505,7 @@ gst_v4l2src_query (GstBaseSrc * bsrc, GstQuery * query)
/* max latency is total duration of the frame buffer */
if (obj->pool != NULL)
num_buffers = GST_V4L2_BUFFER_POOL_CAST (obj->pool)->num_buffers;
num_buffers = GST_V4L2_BUFFER_POOL_CAST (obj->pool)->max_latency;
if (num_buffers == 0)
max_latency = -1;