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bla bla... some new stuff
Original commit message from CVS: bla bla... some new stuff
This commit is contained in:
Ronald S. Bultje
parent
e63c0a9aa2
commit
7af246f2ef
1 changed files with 81 additions and 26 deletions
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@ -100,12 +100,21 @@ I'll give two examples.
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===========
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typedef struct _GstInterface {
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/* dummy */
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/* note: this struct indeed has no parent. That's normal. */
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/* since we will mostly need a pointer to the element,
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* we put it here! */
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GstElement *element;
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} GstInterface;
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/* This small extra virtual function is here to provide an
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* interface functionality on a per-instance basis rather
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* than a per-class basis, which is the case for glib.
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*/
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typedef struct _GstInterfaceClass {
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GTypeInterface parent;
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/* virtual functions */
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gboolean (* supported) (GstInterface *iface);
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} GstInterfaceClass;
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@ -135,6 +144,28 @@ gst_element_implements_interface (GstElement *element,
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return FALSE;
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}
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We could use this in the GST_IS_... () macros. For example, the
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macro GST_IS_MIXER () would then look like this:
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#define GST_IS_MIXER(obj) \
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(G_TYPE_CHECK_INSTANCE_TYPE ((obj), GST_TYPE_MIXER) && \
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gst_element_implements_interface (GST_ELEMENT (obj), \
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GST_TYPE_MIXER))
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So the application would just tread it with the known macro, and
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everything would look extremely simple to the end user.
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Also some convenience function to set the element:
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void
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gst_interface_set_element (GstInterface *iface,
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GstElement *element)
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{
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g_return_if_fail (GST_IS_INTERFACE (iface));
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iface->element = element;
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}
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4a) mixer
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---------
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A mixer is a way of controlling volume and input/output channels.
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@ -147,18 +178,25 @@ input. Indeed, I want both osssrc *and* osssink to export the
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same mixer interface! Or at least a very similar one. Volume
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control works the same for both. You could say that osssrc should
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enumerate the input channels (such as microphone, line-in). Of
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course, osssink should not. Or maybe it should, not sure...
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And alsasink would surely implement the same interface.
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course, osssink should not. Or maybe it should, not sure... Maybe,
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we'd need a parent osselement which implements all mixer channels.
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And alsa* would surely implement the same interface.
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/* This is confusing naming... (i.e. FIXME)
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* A channel is referred to both as the number of simultaneous
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* sounds the input can handle as well as the in-/output itself
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*/
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#define GST_MIXER_CHANNEL_INPUT (1<<0)
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#define GST_MIXER_CHANNEL_OUTPUT (1<<1)
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#define GST_MIXER_CHANNEL_MUTE (1<<2)
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#define GST_MIXER_CHANNEL_RECORD (1<<3)
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typedef struct _GstMixerChannel {
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gchar *label;
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gint current_num_channels,
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max_num_channels;
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max_num_channels,
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flags;
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} GstMixerChannel;
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typedef struct _GstMixer {
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@ -170,17 +208,20 @@ typedef struct _GstMixerClass {
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/* virtual functions */
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GList * (* list_channels) (GstMixer *mixer);
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void (* set_volume) (GstMixer *mixer,
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GstMixerChannel *channel,
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gint *volumes);
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void (* get_volume) (GstMixer *mixer,
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GstMixerChannel *channel,
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gint *volumes);
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void (* set_mute) (GstMixer *mixer,
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GstMixerChannel *channel,
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gboolean mute);
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gboolean (* get_mute) (GstMixer *mixer,
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GstMixerChannel *channel);
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void (* set_record) (GstMixer *mixer,
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GstMixerChannel *channel,
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gboolean record);
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} GstMixerClass;
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Name for in the element list: "mixer". Gstaudio provides wrapper
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@ -192,8 +233,6 @@ How to register these? Let's say that we use osssrc as an example.
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typedef struct _GstOssMixer {
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GstMixer mixer;
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GstElement *element;
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[.. more? ..]
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} GstOssMixer;
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@ -208,17 +247,18 @@ gst_osssrc_init (GstOssSrc *osssrc)
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{
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GstOssMixer *mixer = GST_OSS_MIXER (osssrc);
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[..]
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mixer->element = GST_ELEMENT (osssrc);
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gst_interface_set_element (GST_INTERFACE (mixer),
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GST_ELEMENT (osssrc));
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[..]
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}
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The rest is done automatically, as described in the already-
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mentioned glib documentation for GInterface.
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We could add a pointer to the file descriptor in the
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osssrc/osssink, too, and we'd have full access to the device.
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However, that's implementation. Let's first worry about general
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design.
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mentioned glib documentation for GInterface. This includes
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things like the class_init () function of the GstOssMixerClass,
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which fills all the virtual functions for the mixer, and the
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actual function implementations. The mixer, basically, operates
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as an element on its own. It gets the file descriptor from
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the interface->element (every oss... is a osscommon, etc.).
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4b) overlay
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-----------
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@ -234,18 +274,25 @@ overlay? In the end, users will have to link against either FB
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or X anyway, so we might want to create separate interfaces for
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both. On the other hand, we want to be general too... This is a
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decision that we need to make as early as possible in this process.
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For now, I propose making X- and FB-based interfaces.
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Let's assume that we take X as a basis. Then, overlay becomes as
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simple as one function. Possible extendible by providing inputs
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(like in the mixer) and norms, although that only applies to
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input-to-analog, not to-digital... Discussion needed here!
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input-to-analog, not to-digital... Others simply return NULL.
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#define GST_OVERLAY_CHANNEL_INPUT (1<<0)
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#define GST_OVERLAY_CHANNEL_OUTPUT (1<<1)
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#define GST_OVERLAY_CHANNEL_TUNER (1<<2)
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typedef struct _GstOverlayChannel {
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gchar *label;
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gint flags;
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} GstOverlayChannel;
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typedef struct _GstOverlayNorm {
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gchar *label;
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gfloat framerate;
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} GstOverlayNorm;
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typedef struct _GstOverlay {
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@ -256,16 +303,18 @@ typedef struct _GstOverlayClass {
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GstInterfaceClass klass;
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/* virtual functions */
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GList * (* list_channels) (GstOverlay *overlay);
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void (* set_channel) (GstOverlay *overlay,
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GstOverlayChannel *channel);
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const gchar * (* get_channel) (GstOverlay *overlay);
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GList * (* list_norms) (GstOverlay *overlay);
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void (* set_norm) (GstOverlay *overlay,
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GstOverlayNorm *norm);
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const gchar * (* get_norm) (GstOverlay *overlay);
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void (* set_xwindowid) (GstOverlay *overlay,
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XID xid);
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GList * (* list_channels) (GstOverlay *overlay);
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void (* set_channel) (GstOverlay *overlay,
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gint index);
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gint (* get_channel) (GstOverlay *overlay);
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GList * (* list_norms) (GstOverlay *overlay);
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void (* set_norm) (GstOverlay *overlay,
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gint index);
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gint (* get_norm) (GstOverlay *overlay);
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void (* set_xwindowid) (GstOverlay *overlay,
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XID xid);
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} GstOverlayClass;
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That's all!
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@ -278,6 +327,12 @@ should definately be. And wasn't this one of our key issues for
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No code here. Go implement it, lazy ass!
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General ways of thinking: input can come from a plugin, or from
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the application (we don't have modules for joystick input et all).
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However, plugins handling input (such as dvdsrc) need to be able
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to handle each. So we get both input-to-application as well as
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input-from-application APIs.
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5) Status of this document
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==========================
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This is a proposal, nothing more. Nothing is implemented. Target
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