From e3b49aaa4eed7955e243b110e1209960ba5aaf74 Mon Sep 17 00:00:00 2001 From: Andriy Gelman Date: Sat, 9 May 2020 19:34:41 -0400 Subject: [PATCH] avcodec/v4l2_context: Drop empty packet while draining v4l2_m2m devices may send an empty packet/frame while draining to indicate that all capture buffers have been flushed. Currently, the empty packet/frame is not handled correctly: When encoding, the empty packet is forwarded to the muxer, usually creating warnings. When decoding, a reference to the memory is created anyway. Since in the past this memory contained a decoded frame, it results in an extra frame being decoded. This commit discards the empty packet/frame. References: linux/Documentation/media/uapi/v4l/dev-decoder.rst: "The last buffer may be empty (with :c:type:`v4l2_buffer` bytesused = 0) and in that case it must be ignored by the client, as it does not contain a decoded frame." linux/Documentation/media/uapi/media/v4l/vidioc-encoder-cmd.rst: "...This buffer may be empty, indicated by the driver setting the ``bytesused`` field to 0." Reviewed-by: Ming Qian Signed-off-by: Andriy Gelman --- libavcodec/v4l2_context.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/libavcodec/v4l2_context.c b/libavcodec/v4l2_context.c index f70e151ec8..52dedb119f 100644 --- a/libavcodec/v4l2_context.c +++ b/libavcodec/v4l2_context.c @@ -405,6 +405,15 @@ dequeue: return NULL; } + if (ctx_to_m2mctx(ctx)->draining && !V4L2_TYPE_IS_OUTPUT(ctx->type)) { + int bytesused = V4L2_TYPE_IS_MULTIPLANAR(buf.type) ? + buf.m.planes[0].bytesused : buf.bytesused; + if (bytesused == 0) { + ctx->done = 1; + return NULL; + } + } + avbuf = &ctx->buffers[buf.index]; avbuf->status = V4L2BUF_AVAILABLE; avbuf->buf = buf;