From patchwork Sun Oct 23 12:29:37 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Nicolas George X-Patchwork-Id: 1138 Delivered-To: ffmpegpatchwork@gmail.com Received: by 10.103.140.133 with SMTP id o127csp1767463vsd; Sun, 23 Oct 2016 05:29:49 -0700 (PDT) X-Received: by 10.194.123.197 with SMTP id mc5mr7447197wjb.231.1477225789855; Sun, 23 Oct 2016 05:29:49 -0700 (PDT) Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org. [79.124.17.100]) by mx.google.com with ESMTP id h206si7265594wme.46.2016.10.23.05.29.48; Sun, 23 Oct 2016 05:29:49 -0700 (PDT) Received-SPF: pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) client-ip=79.124.17.100; Authentication-Results: mx.google.com; spf=pass (google.com: domain of ffmpeg-devel-bounces@ffmpeg.org designates 79.124.17.100 as permitted sender) smtp.mailfrom=ffmpeg-devel-bounces@ffmpeg.org Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id D43AE689C0A; Sun, 23 Oct 2016 15:29:43 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from nef2.ens.fr (nef2.ens.fr [129.199.96.40]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id E965E68921C for ; Sun, 23 Oct 2016 15:29:37 +0300 (EEST) Received: from phare.normalesup.org (phare.normalesup.org [129.199.129.80]) by nef2.ens.fr (8.13.6/1.01.28121999) with ESMTP id u9NCTdKI064556 for ; Sun, 23 Oct 2016 14:29:39 +0200 (CEST) Received: by phare.normalesup.org (Postfix, from userid 1001) id 0E2A8E00F1; Sun, 23 Oct 2016 14:29:39 +0200 (CEST) From: Nicolas George To: ffmpeg-devel@ffmpeg.org Date: Sun, 23 Oct 2016 14:29:37 +0200 Message-Id: <20161023122937.21378-1-george@nsup.org> X-Mailer: git-send-email 2.9.3 MIME-Version: 1.0 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (nef2.ens.fr [129.199.96.32]); Sun, 23 Oct 2016 14:29:39 +0200 (CEST) Subject: [FFmpeg-devel] [PATCH] lavd/xcbgrab: do not try to create refcounted packets. X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" The framework will allocate a buffer and copy the data to it, that takes time. But it avoids constently creating and destroyng the shared memory segment, and that saves more time. On my setup, from ~200 to ~300 FPS at full screen (1920×1200), from ~1400 to ~3300 at smaller size (640×480), similar to legacy x11grab. Plus, shared memory segments are a scarce resource, allocating potentially many is a bad idea. Note: if the application were to drop all references to the buffer before the next call to av_read_frame(), then passing the shared memory segment as a refcounted buffer would be even more efficient, but it is hard to guarantee, and it does not happen with the ffmpeg command-line tool. Using a small number of preallocated buffers and resorting to a copy when the pool is exhausted would be a solution to get the better of both worlds. Signed-off-by: Nicolas George Tested-by: Michael --- libavdevice/xcbgrab.c | 65 +++++++++++++++++++++++++++------------------------ 1 file changed, 35 insertions(+), 30 deletions(-) diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c index 9da46c8..702e66c 100644 --- a/libavdevice/xcbgrab.c +++ b/libavdevice/xcbgrab.c @@ -49,6 +49,8 @@ typedef struct XCBGrabContext { const AVClass *class; + uint8_t *buffer; + xcb_connection_t *conn; xcb_screen_t *screen; xcb_window_t window; @@ -219,22 +221,16 @@ static int check_shm(xcb_connection_t *conn) return 0; } -static void dealloc_shm(void *unused, uint8_t *data) -{ - shmdt(data); -} - -static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt) +static int allocate_shm(AVFormatContext *s) { XCBGrabContext *c = s->priv_data; - xcb_shm_get_image_cookie_t iq; - xcb_shm_get_image_reply_t *img; - xcb_drawable_t drawable = c->screen->root; - uint8_t *data; int size = c->frame_size + AV_INPUT_BUFFER_PADDING_SIZE; - int id = shmget(IPC_PRIVATE, size, IPC_CREAT | 0777); - xcb_generic_error_t *e = NULL; + uint8_t *data; + int id; + if (c->buffer) + return 0; + id = shmget(IPC_PRIVATE, size, IPC_CREAT | 0777); if (id == -1) { char errbuf[1024]; int err = AVERROR(errno); @@ -243,15 +239,31 @@ static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt) size, errbuf); return err; } - xcb_shm_attach(c->conn, c->segment, id, 0); + data = shmat(id, NULL, 0); + shmctl(id, IPC_RMID, 0); + if ((intptr_t)data == -1 || !data) + return AVERROR(errno); + c->buffer = data; + return 0; +} + +static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt) +{ + XCBGrabContext *c = s->priv_data; + xcb_shm_get_image_cookie_t iq; + xcb_shm_get_image_reply_t *img; + xcb_drawable_t drawable = c->screen->root; + xcb_generic_error_t *e = NULL; + int ret; + + ret = allocate_shm(s); + if (ret < 0) + return ret; iq = xcb_shm_get_image(c->conn, drawable, c->x, c->y, c->width, c->height, ~0, XCB_IMAGE_FORMAT_Z_PIXMAP, c->segment, 0); - - xcb_shm_detach(c->conn, c->segment); - img = xcb_shm_get_image_reply(c->conn, iq, &e); xcb_flush(c->conn); @@ -264,25 +276,12 @@ static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt) e->response_type, e->error_code, e->sequence, e->resource_id, e->minor_code, e->major_code); - shmctl(id, IPC_RMID, 0); return AVERROR(EACCES); } free(img); - data = shmat(id, NULL, 0); - shmctl(id, IPC_RMID, 0); - - if ((intptr_t)data == -1) - return AVERROR(errno); - - pkt->buf = av_buffer_create(data, size, dealloc_shm, NULL, 0); - if (!pkt->buf) { - shmdt(data); - return AVERROR(ENOMEM); - } - - pkt->data = pkt->buf->data; + pkt->data = c->buffer; pkt->size = c->frame_size; return 0; @@ -436,6 +435,12 @@ static av_cold int xcbgrab_read_close(AVFormatContext *s) { XCBGrabContext *ctx = s->priv_data; +#if CONFIG_LIBXCB_SHM + if (ctx->buffer) { + shmdt(ctx->buffer); + } +#endif + xcb_disconnect(ctx->conn); return 0;