From 19202b54698b343a0207d7e213448e32b8e58fc3 Mon Sep 17 00:00:00 2001
From: Olliver Schinagl <o.schinagl@ultimaker.com>
Date: Wed, 29 Oct 2014 09:34:41 +0100
Subject: [PATCH 1/7] Buffer the bytesused variable from struct v4l2_buffer

Starting with kernel versions 3.16, (DE)Queing of buffers has been fixed
after it was leaking data for ages. in the struct v4l2_buffer is the
bytesused element which indicates the size of the buffer. This however
gets cleared whenever the buffer gets requeued and is thus no longer
valid.

This patch copies the bytesused variable so it is available until the
next frame captured again.

Signed-off-by: Olliver Schinagl <o.schinagl@ultimaker.com>
---
 plugins/input_uvc/input_uvc.c | 6 +++---
 plugins/input_uvc/v4l2uvc.c   | 2 ++
 plugins/input_uvc/v4l2uvc.h   | 1 +
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/plugins/input_uvc/input_uvc.c b/plugins/input_uvc/input_uvc.c
index e6c74fd..64f66cb 100644
--- a/plugins/input_uvc/input_uvc.c
+++ b/plugins/input_uvc/input_uvc.c
@@ -482,7 +482,7 @@ void *cam_thread(void *arg)
             exit(EXIT_FAILURE);
         }
 
-        //DBG("received frame of size: %d from plugin: %d\n", pcontext->videoIn->buf.bytesused, pcontext->id);
+        //DBG("received frame of size: %d from plugin: %d\n", pcontext->videoIn->tmpbytesused, pcontext->id);
 
         /*
          * Workaround for broken, corrupted frames:
@@ -491,7 +491,7 @@ void *cam_thread(void *arg)
          * For example a VGA (640x480) webcam picture is normally >= 8kByte large,
          * corrupted frames are smaller.
          */
-        if(pcontext->videoIn->buf.bytesused < minimum_size) {
+        if(pcontext->videoIn->tmpbytesused < minimum_size) {
             DBG("dropping too small frame, assuming it as broken\n");
             continue;
         }
@@ -529,7 +529,7 @@ void *cam_thread(void *arg)
         } else {
         #endif
             //DBG("copying frame from input: %d\n", (int)pcontext->id);
-            pglobal->in[pcontext->id].size = memcpy_picture(pglobal->in[pcontext->id].buf, pcontext->videoIn->tmpbuffer, pcontext->videoIn->buf.bytesused);
+            pglobal->in[pcontext->id].size = memcpy_picture(pglobal->in[pcontext->id].buf, pcontext->videoIn->tmpbuffer, pcontext->videoIn->tmpbytesused);
         #ifndef NO_LIBJPEG
         }
         #endif
diff --git a/plugins/input_uvc/v4l2uvc.c b/plugins/input_uvc/v4l2uvc.c
index c5a5aa4..d11510c 100644
--- a/plugins/input_uvc/v4l2uvc.c
+++ b/plugins/input_uvc/v4l2uvc.c
@@ -532,6 +532,7 @@ int uvcGrab(struct vdIn *vd)
         */
 
         memcpy(vd->tmpbuffer, vd->mem[vd->buf.index], vd->buf.bytesused);
+	vd->tmpbytesused = vd->buf.bytesused;
 
         if(debug)
             fprintf(stderr, "bytes in used %d \n", vd->buf.bytesused);
@@ -570,6 +571,7 @@ int close_v4l2(struct vdIn *vd)
     if(vd->tmpbuffer)
         free(vd->tmpbuffer);
     vd->tmpbuffer = NULL;
+    vd->tmpbytesused = 0;
     free(vd->framebuffer);
     vd->framebuffer = NULL;
     free(vd->videodevice);
diff --git a/plugins/input_uvc/v4l2uvc.h b/plugins/input_uvc/v4l2uvc.h
index 022c57e..2c7c8ba 100644
--- a/plugins/input_uvc/v4l2uvc.h
+++ b/plugins/input_uvc/v4l2uvc.h
@@ -83,6 +83,7 @@ struct vdIn {
     struct v4l2_requestbuffers rb;
     void *mem[NB_BUFFER];
     unsigned char *tmpbuffer;
+    int tmpbytesused;
     unsigned char *framebuffer;
     streaming_state streamingState;
     int grabmethod;
-- 
1.9.1