Re: [PATCH v1 1/7] ui/spice: Add an option for users to provide a preferred codec

[Marc-André Lureau]

Hi

On Sat, Jan 20, 2024 at 4:54 AM Vivek Kasireddy
<vivek.kasireddy@intel.com> wrote:
>
> Giving users an option to choose a particular codec will enable
> them to make an appropriate decision based on their hardware and
> use-case.
>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
> Cc: Frediano Ziglio <freddy77@gmail.com>
> Cc: Dongwon Kim <dongwon.kim@intel.com>
> Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
>
> ---
> v2:
> - Don't override the default Spice codec if preferred-codec is not
>   provided (Frediano)
> ---
>  qemu-options.hx |  5 +++++
>  ui/spice-core.c | 12 ++++++++++++
>  2 files changed, 17 insertions(+)
>
> diff --git a/qemu-options.hx b/qemu-options.hx
> index b66570ae00..caaafe01d5 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -2260,6 +2260,7 @@ DEF("spice", HAS_ARG, QEMU_OPTION_spice,
>      "       
> [,streaming-video=[off|all|filter]][,disable-copy-paste=on|off]\n"
>      "       [,disable-agent-file-xfer=on|off][,agent-mouse=[on|off]]\n"
>      "       [,playback-compression=[on|off]][,seamless-migration=[on|off]]\n"
> +    "       [,preferred-codec=<encoder>:<codec>\n"

The SPICE API is "spice_server_set_video_codecs()", let's name the
option: "video-codecs" to avoid confusions.

>      "       [,gl=[on|off]][,rendernode=<file>]\n"
>      "                enable spice\n"
>      "                at least one of {port, tls-port} is mandatory\n",
> @@ -2348,6 +2349,10 @@ SRST
>      ``seamless-migration=[on|off]``
>          Enable/disable spice seamless migration. Default is off.
>
> +    ``preferred-codec=<encoder>:<codec>``
> +        Provide the preferred codec the Spice server should use.
> +        Default would be spice:mjpeg.

The SPICE API says:
 * @codecs: a codec string in the following format: encoder:codec;encoder:codec

But the doc doesn't say whether the order is important, and doesn't
give more details on the "encoder:codec" format.

Also reading the code, it seems "auto" has a special meaning for
default video codecs.

> +
>      ``gl=[on|off]``
>          Enable/disable OpenGL context. Default is off.
>
> diff --git a/ui/spice-core.c b/ui/spice-core.c
> index db21db2c94..13bfbe4e89 100644
> --- a/ui/spice-core.c
> +++ b/ui/spice-core.c
> @@ -488,6 +488,9 @@ static QemuOptsList qemu_spice_opts = {
>          },{
>              .name = "streaming-video",
>              .type = QEMU_OPT_STRING,
> +        },{
> +            .name = "preferred-codec",
> +            .type = QEMU_OPT_STRING,
>          },{
>              .name = "agent-mouse",
>              .type = QEMU_OPT_BOOL,
> @@ -663,6 +666,7 @@ static void qemu_spice_init(void)
>      char *x509_key_file = NULL,
>          *x509_cert_file = NULL,
>          *x509_cacert_file = NULL;
> +    const char *preferred_codec = NULL;
>      int port, tls_port, addr_flags;
>      spice_image_compression_t compression;
>      spice_wan_compression_t wan_compr;
> @@ -802,6 +806,14 @@ static void qemu_spice_init(void)
>          spice_server_set_streaming_video(spice_server, 
> SPICE_STREAM_VIDEO_OFF);
>      }
>
> +    preferred_codec = qemu_opt_get(opts, "preferred-codec");
> +    if (preferred_codec) {
> +        if (spice_server_set_video_codecs(spice_server, preferred_codec)) {

Sadly, the API just returns 0 if one of the codec was accepted, not
great if you want a specific set of codecs.

otherwise, lgtm


> +            error_report("Preferred codec name is not valid");
> +            exit(1);
> +        }
> +    }
> +
>      spice_server_set_agent_mouse
>          (spice_server, qemu_opt_get_bool(opts, "agent-mouse", 1));
>      spice_server_set_playback_compression
> --
> 2.39.2
>
>


--
Marc-André Lureau