On Fri, Apr 18, 2025 at 01:29:47PM +0200, Dietmar Maurer wrote:
> The H264 implementation only sends frames when it detects changes in
> the server's framebuffer. This leads to artifacts when there are no
> further changes, as the internal H264 encoder may still contain data.
>
> This patch modifies the code to send a few additional frames in such
> situations to flush the H264 encoder data.
>
> Signed-off-by: Dietmar Maurer <diet...@proxmox.com>
> ---
> ui/vnc.c | 25 ++++++++++++++++++++++++-
> ui/vnc.h | 3 +++
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/ui/vnc.c b/ui/vnc.c
> index aed25b0183..badc7912c0 100644
> --- a/ui/vnc.c
> +++ b/ui/vnc.c
> @@ -3239,7 +3239,30 @@ static void vnc_refresh(DisplayChangeListener *dcl)
> vnc_unlock_display(vd);
>
> QTAILQ_FOREACH_SAFE(vs, &vd->clients, next, vn) {
> - rects += vnc_update_client(vs, has_dirty);
> + int client_dirty = has_dirty;
> + if (vs->h264) {
> + if (client_dirty) {
> + vs->h264->keep_dirty = VNC_H264_KEEP_DIRTY;
> + } else {
> + if (vs->h264->keep_dirty > 0) {
> + client_dirty = 1;
> + vs->h264->keep_dirty--;
> + }
> + }
> + }
> +
> + int count = vnc_update_client(vs, client_dirty);
> + rects += count;
> +
> + if (vs->h264 && !count && vs->h264->keep_dirty) {
> + VncJob *job = vnc_job_new(vs);
> + int height = pixman_image_get_height(vd->server);
> + int width = pixman_image_get_width(vd->server);
> + vs->job_update = vs->update;
> + vs->update = VNC_STATE_UPDATE_NONE;
> + vnc_job_add_rect(job, 0, 0, width, height);
> + vnc_job_push(job);
> + }
> /* vs might be free()ed here */
This comment is telling you that 'vnc_update_client' may have
released 'vs', and yet this code is referencing 'vs->...'
and so will be liable to crash.
> }
>
With regards,
Daniel
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