From 0cd4faf977f034c603cb2d5c6bb84e728ed3fab3 Mon Sep 17 00:00:00 2001
From: Panagiotis Issaris <takis.issaris@uhasselt.be>
Date: Fri, 15 Dec 2006 13:19:03 +0000
Subject: [PATCH] Allow provision of displaynumber, screennumber, x-offset and
 y-offset parameters to the x11grab device.

Originally committed as revision 7320 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 doc/ffmpeg-doc.texi   |  7 +++++++
 libavformat/x11grab.c | 29 +++++++++++++++++++++--------
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/doc/ffmpeg-doc.texi b/doc/ffmpeg-doc.texi
index d9d30ee7f4..470cfe3c10 100644
--- a/doc/ffmpeg-doc.texi
+++ b/doc/ffmpeg-doc.texi
@@ -50,6 +50,13 @@ ffmpeg -f x11grab -vd x11:0.0 /tmp/out.mpg
 0.0 is display.screen number of your X11 server, same as
 the DISPLAY environment variable.
 
+@example
+ffmpeg -f x11grab -vd x11:0.0+10,20 /tmp/out.mpg
+@end example
+
+0.0 is display.screen number of your X11 server, same as the DISPLAY environment
+variable. 10 is the x-offset and 20 the y-offset for the grabbing.
+
 @section Video and Audio file format conversion
 
 * FFmpeg can use any supported file format and protocol as input:
diff --git a/libavformat/x11grab.c b/libavformat/x11grab.c
index 4b237f6c26..48ef3d7256 100644
--- a/libavformat/x11grab.c
+++ b/libavformat/x11grab.c
@@ -94,20 +94,33 @@ x11grab_read_header(AVFormatContext *s1, AVFormatParameters *ap)
     int x_off = 0;
     int y_off = 0;
     int use_shm;
-
-    dpy = XOpenDisplay(NULL);
-    if(!dpy) {
-        av_free(st);
-        return AVERROR_IO;
-    }
+    char *param, *offset;
 
     if (!ap->device) {
         av_log(s1, AV_LOG_ERROR, "AVParameters don't specify any device. Use -vd.\n");
         return AVERROR_IO;
     }
 
-    sscanf(ap->device, "x11:%d,%d", &x_off, &y_off);
-    av_log(s1, AV_LOG_INFO, "device: %s -> x: %d y: %d width: %d height: %d\n", ap->device, x_off, y_off, ap->width, ap->height);
+    param = strchr(ap->device, ':');
+    if (!param) {
+        av_free(st);
+        return AVERROR_IO;
+    }
+
+    param = av_strdup(param);
+    offset = strchr(param, '+');
+    if (offset) {
+        sscanf(offset, "%d,%d", &x_off, &y_off);
+        *offset= 0;
+    }
+
+    av_log(s1, AV_LOG_INFO, "device: %s -> display: %s x: %d y: %d width: %d height: %d\n", ap->device, param, x_off, y_off, ap->width, ap->height);
+
+    dpy = XOpenDisplay(param);
+    if(!dpy) {
+        av_log(s1, AV_LOG_ERROR, "Could not open X display.\n");
+        return AVERROR_IO;
+    }
 
     if (!ap || ap->width <= 0 || ap->height <= 0 || ap->time_base.den <= 0) {
         av_log(s1, AV_LOG_ERROR, "AVParameters don't have any video size. Use -s.\n");