From: Andriy Gelman <andriy.gel...@gmail.com>
v4l2_m2m uses device memory mapped buffers to store dequeued
frames/packets (reference counted by AVBufferRef). When the
reference count drops to zero, the buffer ownership is returned back to
the device, so that they can re-filled with frames/packets.
There are some cases when all the buffers are in userspace (i.e. due to
internal buffering in ffmpeg). On the s5p-mfc this causes an infinite
wait when polling to dequeue the buffers, which can be prevented by
increasing the total number of capture buffers. This commit adds a
warning when this occurs.
Signed-off-by: Andriy Gelman <andriy.gel...@gmail.com>
---
libavcodec/v4l2_context.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c
index 31af10d28e..5145772c45 100644
--- a/libavcodec/v4l2_context.c
+++ b/libavcodec/v4l2_context.c
@@ -285,6 +285,18 @@ static V4L2Buffer* v4l2_dequeue_v4l2buf(V4L2Context *ctx,
int timeout)
};
int i, ret;
+ if (!V4L2_TYPE_IS_OUTPUT(ctx->type) && ctx->buffers) {
+ for (i = 0; i < ctx->num_buffers; i++) {
+ if (ctx->buffers[i].status == V4L2BUF_IN_DRIVER)
+ break;
+ }
+ if (i == ctx->num_buffers)
+ av_log(logger(ctx), AV_LOG_WARNING, "All capture buffers returned
to "
+ "userspace. Increase
num_capture_buffers "
+ "to prevent device deadlock or
dropped "
+ "packets/frames.\n");
+ }
+
/* if we are draining and there are no more capture buffers queued in the
driver we are done */
if (!V4L2_TYPE_IS_OUTPUT(ctx->type) && ctx_to_m2mctx(ctx)->draining) {
for (i = 0; i < ctx->num_buffers; i++) {
--
2.25.1
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