Hi
On Fri, Apr 18, 2025 at 3:41 PM Dietmar Maurer <diet...@proxmox.com> wrote:
>
> This patch implements H264 support for VNC. The RFB protocol
> extension is defined in:
>
> https://github.com/rfbproto/rfbproto/blob/master/rfbproto.rst#open-h-264-encoding
>
> Currently the Gstreamer x264enc plugin (software encoder) is used
> to encode the video stream.
>
> The gstreamer pipe is:
>
> appsrc -> videoconvert -> x264enc -> appsink
>
> Note: videoconvert is required for RGBx to YUV420 conversion.
>
> The code still use the VNC server framebuffer change detection,
> and only encodes and sends video frames if there are changes.
>
> Signed-off-by: Dietmar Maurer <diet...@proxmox.com>
> ---
> ui/meson.build | 1 +
> ui/vnc-enc-h264.c | 282 ++++++++++++++++++++++++++++++++++++++++++++++
> ui/vnc-jobs.c | 49 +++++---
> ui/vnc.c | 21 ++++
> ui/vnc.h | 21 ++++
> 5 files changed, 359 insertions(+), 15 deletions(-)
> create mode 100644 ui/vnc-enc-h264.c
>
> diff --git a/ui/meson.build b/ui/meson.build
> index 35fb04cadf..34f1f33699 100644
> --- a/ui/meson.build
> +++ b/ui/meson.build
> @@ -46,6 +46,7 @@ vnc_ss.add(files(
> ))
> vnc_ss.add(zlib, jpeg)
> vnc_ss.add(when: sasl, if_true: files('vnc-auth-sasl.c'))
> +vnc_ss.add(when: gstreamer, if_true: files('vnc-enc-h264.c'))
> system_ss.add_all(when: [vnc, pixman], if_true: vnc_ss)
> system_ss.add(when: vnc, if_false: files('vnc-stubs.c'))
>
> diff --git a/ui/vnc-enc-h264.c b/ui/vnc-enc-h264.c
> new file mode 100644
> index 0000000000..3abe6a1528
> --- /dev/null
> +++ b/ui/vnc-enc-h264.c
> @@ -0,0 +1,282 @@
> +/*
> + * QEMU VNC display driver: hextile encoding
> + *
> + * Copyright (C) 2025 Proxmox Server Solutions GmbH
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> copy
> + * of this software and associated documentation files (the "Software"), to
> deal
> + * in the Software without restriction, including without limitation the
> rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "vnc.h"
> +
> +#include <gst/gst.h>
> +
> +static void destroy_encoder_context(VncState *vs)
> +{
> + gst_clear_object(&vs->h264->source);
> + gst_clear_object(&vs->h264->convert);
> + gst_clear_object(&vs->h264->gst_encoder);
> + gst_clear_object(&vs->h264->sink);
> + gst_clear_object(&vs->h264->pipeline);
> +}
> +
> +static bool create_encoder_context(VncState *vs, int w, int h)
> +{
> + g_autoptr(GstCaps) source_caps = NULL;
> + GstStateChangeReturn state_change_ret;
> +
> + g_assert(vs->h264 != NULL);
> +
> + if (vs->h264->sink) {
> + if (w != vs->h264->width || h != vs->h264->height) {
> + destroy_encoder_context(vs);
> + }
> + }
> +
> + if (vs->h264->sink) {
> + return TRUE;
> + }
I suggest to move that condition in the previous block (.. else {
return TRUE; }) for readibility
> +
> + vs->h264->width = w;
> + vs->h264->height = h;
> +
> + vs->h264->source = gst_element_factory_make("appsrc", "source");
> + if (!vs->h264->source) {
> + VNC_DEBUG("Could not create gst source\n");
> + goto error;
> + }
> +
> + vs->h264->convert = gst_element_factory_make("videoconvert", "convert");
> + if (!vs->h264->convert) {
> + VNC_DEBUG("Could not create gst convert element\n");
> + goto error;
> + }
> +
> + vs->h264->gst_encoder = gst_element_factory_make("x264enc",
> "gst-encoder");
> + if (!vs->h264->gst_encoder) {
> + VNC_DEBUG("Could not create gst x264 encoder\n");
> + goto error;
> + }
> +
> + g_object_set(
> + vs->h264->gst_encoder,
> + "tune", 4, /* zerolatency */
> + /*
> + * fix for zerolatency with novnc (without, noVNC displays
> + * green stripes)
> + */
> + "threads", 1,
> + "pass", 5, /* Constant Quality */
> + "quantizer", 26,
> + /* avoid access unit delimiters (Nal Unit Type 9) - not required */
> + "aud", false,
> + NULL);
> +
> + vs->h264->sink = gst_element_factory_make("appsink", "sink");
> + if (!vs->h264->sink) {
> + VNC_DEBUG("Could not create gst sink\n");
> + goto error;
> + }
> +
> + vs->h264->pipeline = gst_pipeline_new("vnc-h264-pipeline");
> + if (!vs->h264->pipeline) {
> + VNC_DEBUG("Could not create gst pipeline\n");
> + goto error;
> + }
> +
> + gst_object_ref(vs->h264->source);
> + if (!gst_bin_add(GST_BIN(vs->h264->pipeline), vs->h264->source)) {
> + gst_object_unref(vs->h264->source);
I think it's a bit unnecessary to ref/unref each element, this is not
typically what the gst API recommends. See for ex
https://gstreamer.freedesktop.org/documentation/tutorials/basic/dynamic-pipelines.html?gi-language=c.
They rely on weak pointers.
> + VNC_DEBUG("Could not add source to gst pipeline\n");
> + goto error;
> + }
> +
> + gst_object_ref(vs->h264->convert);
> + if (!gst_bin_add(GST_BIN(vs->h264->pipeline), vs->h264->convert)) {
Can you use gst_bin_add_many() ?
> + gst_object_unref(vs->h264->convert);
> + VNC_DEBUG("Could not add convert to gst pipeline\n");
> + goto error;
> + }
> +
> + gst_object_ref(vs->h264->gst_encoder);
> + if (!gst_bin_add(GST_BIN(vs->h264->pipeline), vs->h264->gst_encoder)) {
> + gst_object_unref(vs->h264->gst_encoder);
> + VNC_DEBUG("Could not add encoder to gst pipeline\n");
> + goto error;
> + }
> +
> + gst_object_ref(vs->h264->sink);
> + if (!gst_bin_add(GST_BIN(vs->h264->pipeline), vs->h264->sink)) {
> + gst_object_unref(vs->h264->sink);
> + VNC_DEBUG("Could not add sink to gst pipeline\n");
> + goto error;
> + }
> +
> + source_caps = gst_caps_new_simple(
> + "video/x-raw",
> + "format", G_TYPE_STRING, "BGRx",
> + "framerate", GST_TYPE_FRACTION, 33, 1,
> + "width", G_TYPE_INT, w,
> + "height", G_TYPE_INT, h,
> + NULL);
> +
> + if (!source_caps) {
> + VNC_DEBUG("Could not create source caps filter\n");
> + goto error;
> + }
> +
> + g_object_set(vs->h264->source, "caps", source_caps, NULL);
> +
> + if (gst_element_link_many(
> + vs->h264->source,
> + vs->h264->convert,
> + vs->h264->gst_encoder,
> + vs->h264->sink,
> + NULL
> + ) != TRUE) {
> + VNC_DEBUG("Elements could not be linked.\n");
> + goto error;
> + }
> +
> + /* Start playing */
> + state_change_ret = gst_element_set_state(
> + vs->h264->pipeline, GST_STATE_PLAYING);
> +
> + if (state_change_ret == GST_STATE_CHANGE_FAILURE) {
> + VNC_DEBUG("Unable to set the pipeline to the playing state.\n");
> + goto error;
> + }
> +
> + return TRUE;
> +
> + error:
> + destroy_encoder_context(vs);
> + return FALSE;
> +}
> +
> +bool vnc_h264_encoder_init(VncState *vs)
> +{
> + g_assert(vs->h264 == NULL);
> +
> + vs->h264 = g_new0(VncH264, 1);
> +
> + return true;
> +}
> +
> +/*
> + * Returns the number of generated framebuffer updates,
> + * or -1 in case of errors
> + */
> +int vnc_h264_send_framebuffer_update(
> + VncState *vs,
> + int _x,
> + int _y,
> + int _w,
> + int _h
> +) {
> + int n = 0;
> + int rdb_h264_flags = 0;
> + int width, height;
> + uint8_t *src_data_ptr = NULL;
> + size_t src_data_size;
> + GstFlowReturn flow_ret = GST_FLOW_ERROR;
> + GstBuffer *src_buffer = NULL;
> +
> + g_assert(vs->h264 != NULL);
> + g_assert(vs->vd != NULL);
> + g_assert(vs->vd->server != NULL);
> +
> + width = pixman_image_get_width(vs->vd->server);
> + height = pixman_image_get_height(vs->vd->server);
> +
> + g_assert(width == vs->client_width);
> + g_assert(height == vs->client_height);
> +
> + if (vs->h264->sink) {
> + if (width != vs->h264->width || height != vs->h264->height) {
> + rdb_h264_flags = 2;
> + }
> + } else {
> + rdb_h264_flags = 2;
> + }
> +
> + if (!create_encoder_context(vs, width, height)) {
> + VNC_DEBUG("Create encoder context failed\n");
> + return -1;
> + }
> +
> + g_assert(vs->h264->sink != NULL);
> +
> + src_data_ptr = vnc_server_fb_ptr(vs->vd, 0, 0);
> + src_data_size = width * height * VNC_SERVER_FB_BYTES;
> +
> + src_buffer = gst_buffer_new_wrapped_full(
> + 0, src_data_ptr, src_data_size, 0, src_data_size, NULL, NULL);
> +
> + g_signal_emit_by_name(
> + vs->h264->source, "push-buffer", src_buffer, &flow_ret);
> +
> + if (flow_ret != GST_FLOW_OK) {
> + VNC_DEBUG("gst appsrc push buffer failed\n");
> + return -1;
> + }
> +
> + do {
> + GstSample *sample = NULL;
> + GstMapInfo map;
> + GstBuffer *out_buffer;
> +
> + /* Retrieve the buffer */
> + g_signal_emit_by_name(vs->h264->sink, "try-pull-sample", 0, &sample);
> + if (!sample) {
> + break;
> + }
> + out_buffer = gst_sample_get_buffer(sample);
> + if (gst_buffer_map(out_buffer, &map, 0)) {
> + vnc_framebuffer_update(vs, 0, 0, width, height,
> VNC_ENCODING_H264);
> + vnc_write_s32(vs, map.size); /* write data length */
> + vnc_write_s32(vs, rdb_h264_flags); /* write flags */
> + rdb_h264_flags = 0;
> +
> + VNC_DEBUG("GST vnc_h264_update send %ld\n", map.size);
> +
> + vnc_write(vs, map.data, map.size);
> +
> + gst_buffer_unmap(out_buffer, &map);
> +
> + n += 1;
> + } else {
> + VNC_DEBUG("unable to map sample\n");
> + }
> + gst_sample_unref(sample);
> + } while (true);
> +
> + return n;
> +}
> +
> +void vnc_h264_clear(VncState *vs)
> +{
> + if (!vs->h264) {
> + return;
> + }
unnecessary
> +
> + destroy_encoder_context(vs);
> +
> + g_clear_pointer(&vs->h264, g_free);
> +}
> diff --git a/ui/vnc-jobs.c b/ui/vnc-jobs.c
> index fcca7ec632..853a547d9a 100644
> --- a/ui/vnc-jobs.c
> +++ b/ui/vnc-jobs.c
> @@ -193,6 +193,7 @@ static void vnc_async_encoding_start(VncState *orig,
> VncState *local)
> local->zlib = orig->zlib;
> local->hextile = orig->hextile;
> local->zrle = orig->zrle;
> + local->h264 = orig->h264;
> local->client_width = orig->client_width;
> local->client_height = orig->client_height;
> }
> @@ -204,6 +205,7 @@ static void vnc_async_encoding_end(VncState *orig,
> VncState *local)
> orig->zlib = local->zlib;
> orig->hextile = local->hextile;
> orig->zrle = local->zrle;
> + orig->h264 = local->h264;
> orig->lossy_rect = local->lossy_rect;
> }
>
> @@ -284,25 +286,42 @@ static int vnc_worker_thread_loop(VncJobQueue *queue)
> vnc_write_u16(&vs, 0);
>
> vnc_lock_display(job->vs->vd);
> - QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
> - int n;
> -
> - if (job->vs->ioc == NULL) {
> - vnc_unlock_display(job->vs->vd);
> - /* Copy persistent encoding data */
> - vnc_async_encoding_end(job->vs, &vs);
> - goto disconnected;
> - }
>
> - if (vnc_worker_clamp_rect(&vs, job, &entry->rect)) {
> - n = vnc_send_framebuffer_update(&vs, entry->rect.x,
> entry->rect.y,
> - entry->rect.w, entry->rect.h);
> + if (vs.vnc_encoding == VNC_ENCODING_H264) {
> + int width = pixman_image_get_width(vs.vd->server);
> + int height = pixman_image_get_height(vs.vd->server);
> + int n = vnc_send_framebuffer_update(&vs, 0, 0, width, height);
> + if (n >= 0) {
> + n_rectangles += n;
> + }
> + QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
> + g_free(entry);
> + }
> + } else {
> + QLIST_FOREACH_SAFE(entry, &job->rectangles, next, tmp) {
> + int n;
> +
> + if (job->vs->ioc == NULL) {
> + vnc_unlock_display(job->vs->vd);
> + /* Copy persistent encoding data */
> + vnc_async_encoding_end(job->vs, &vs);
> + goto disconnected;
> + }
>
> - if (n >= 0) {
> - n_rectangles += n;
> + if (vnc_worker_clamp_rect(&vs, job, &entry->rect)) {
> + n = vnc_send_framebuffer_update(
> + &vs,
> + entry->rect.x,
> + entry->rect.y,
> + entry->rect.w,
> + entry->rect.h);
> +
> + if (n >= 0) {
> + n_rectangles += n;
> + }
> }
> + g_free(entry);
> }
> - g_free(entry);
> }
> trace_vnc_job_nrects(&vs, job, n_rectangles);
> vnc_unlock_display(job->vs->vd);
> diff --git a/ui/vnc.c b/ui/vnc.c
> index 9241caaad9..aed25b0183 100644
> --- a/ui/vnc.c
> +++ b/ui/vnc.c
> @@ -972,6 +972,9 @@ int vnc_send_framebuffer_update(VncState *vs, int x, int
> y, int w, int h)
> case VNC_ENCODING_ZYWRLE:
> n = vnc_zywrle_send_framebuffer_update(vs, x, y, w, h);
> break;
> + case VNC_ENCODING_H264:
> + n = vnc_h264_send_framebuffer_update(vs, x, y, w, h);
> + break;
> default:
> vnc_framebuffer_update(vs, x, y, w, h, VNC_ENCODING_RAW);
> n = vnc_raw_send_framebuffer_update(vs, x, y, w, h);
> @@ -1326,6 +1329,10 @@ void vnc_disconnect_finish(VncState *vs)
> vnc_tight_clear(vs);
> vnc_zrle_clear(vs);
>
> +#ifdef CONFIG_GSTREAMER
> + vnc_h264_clear(vs);
> +#endif
> +
> #ifdef CONFIG_VNC_SASL
> vnc_sasl_client_cleanup(vs);
> #endif /* CONFIG_VNC_SASL */
> @@ -2181,6 +2188,16 @@ static void set_encodings(VncState *vs, int32_t
> *encodings, size_t n_encodings)
> vnc_set_feature(vs, VNC_FEATURE_ZYWRLE);
> vs->vnc_encoding = enc;
> break;
> +#ifdef CONFIG_GSTREAMER
> + case VNC_ENCODING_H264:
> + if (vnc_h264_encoder_init(vs)) {
> + vnc_set_feature(vs, VNC_FEATURE_H264);
> + vs->vnc_encoding = enc;
> + } else {
> + VNC_DEBUG("vnc_h264_encoder_init failed\n");
> + }
> + break;
> +#endif
> case VNC_ENCODING_DESKTOPRESIZE:
> vnc_set_feature(vs, VNC_FEATURE_RESIZE);
> break;
> @@ -4291,6 +4308,10 @@ int vnc_init_func(void *opaque, QemuOpts *opts, Error
> **errp)
> Error *local_err = NULL;
> char *id = (char *)qemu_opts_id(opts);
>
> +#ifdef CONFIG_GSTREAMER
> + gst_init(NULL, NULL);
> +#endif
> +
> assert(id);
> vnc_display_init(id, &local_err);
> if (local_err) {
> diff --git a/ui/vnc.h b/ui/vnc.h
> index acc53a2cc1..a0d336738d 100644
> --- a/ui/vnc.h
> +++ b/ui/vnc.h
> @@ -46,6 +46,10 @@
> #include "vnc-enc-zrle.h"
> #include "ui/kbd-state.h"
>
> +#ifdef CONFIG_GSTREAMER
> +#include <gst/gst.h>
> +#endif
> +
> // #define _VNC_DEBUG 1
>
> #ifdef _VNC_DEBUG
> @@ -231,6 +235,14 @@ typedef struct VncZywrle {
> int buf[VNC_ZRLE_TILE_WIDTH * VNC_ZRLE_TILE_HEIGHT];
> } VncZywrle;
>
> +#ifdef CONFIG_GSTREAMER
> +typedef struct VncH264 {
> + GstElement *pipeline, *source, *gst_encoder, *sink, *convert;
> + size_t width;
> + size_t height;
> +} VncH264;
> +#endif
> +
> struct VncRect
> {
> int x;
> @@ -344,6 +356,9 @@ struct VncState
> VncHextile hextile;
> VncZrle *zrle;
> VncZywrle zywrle;
> +#ifdef CONFIG_GSTREAMER
> + VncH264 *h264;
> +#endif
>
> Notifier mouse_mode_notifier;
>
> @@ -404,6 +419,7 @@ enum {
> #define VNC_ENCODING_TRLE 0x0000000f
> #define VNC_ENCODING_ZRLE 0x00000010
> #define VNC_ENCODING_ZYWRLE 0x00000011
> +#define VNC_ENCODING_H264 0x00000032 /* 50 */
> #define VNC_ENCODING_COMPRESSLEVEL0 0xFFFFFF00 /* -256 */
> #define VNC_ENCODING_QUALITYLEVEL0 0xFFFFFFE0 /* -32 */
> #define VNC_ENCODING_XCURSOR 0xFFFFFF10 /* -240 */
> @@ -464,6 +480,7 @@ enum VncFeatures {
> VNC_FEATURE_XVP,
> VNC_FEATURE_CLIPBOARD_EXT,
> VNC_FEATURE_AUDIO,
> + VNC_FEATURE_H264,
> };
>
>
> @@ -625,6 +642,10 @@ int vnc_zrle_send_framebuffer_update(VncState *vs, int
> x, int y, int w, int h);
> int vnc_zywrle_send_framebuffer_update(VncState *vs, int x, int y, int w,
> int h);
> void vnc_zrle_clear(VncState *vs);
>
> +bool vnc_h264_encoder_init(VncState *vs);
> +int vnc_h264_send_framebuffer_update(VncState *vs, int x, int y, int w, int
> h);
> +void vnc_h264_clear(VncState *vs);
> +
> /* vnc-clipboard.c */
> void vnc_server_cut_text_caps(VncState *vs);
> void vnc_client_cut_text(VncState *vs, size_t len, uint8_t *text);
> --
> 2.39.5
>
>
--
Marc-André Lureau
