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

[Kasireddy, Vivek]

Hi Marc-Andre,

> 
> 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.
I am ok with "video-codes" instead of "preferred-codec".

> 
> >      "       [,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.
Although, I am using spice_server_set_video_codecs() API, my initial goal
with this option is for the user to specify one <encoder>:<codec> entry
only. I guess it might be OK to have the user specify a list as long as Spice 
picks
the first entry (aka preferred) and falls back to the next if it cannot create 
or
use the encoder associated with the first entry.

> 
> > +
> >      ``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.
IIUC, although a user can specify a set of codecs, only one can by actively 
used at
any given time (at-least with Gstreamer ones, not Spice codecs) with my 
use-case (gl=on).

Thanks,
Vivek

> 
> 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