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Diffstat (limited to 'glew/auto/EGL-Registry/extensions/NV/EGL_NV_stream_sync.txt')
| -rw-r--r-- | glew/auto/EGL-Registry/extensions/NV/EGL_NV_stream_sync.txt | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/glew/auto/EGL-Registry/extensions/NV/EGL_NV_stream_sync.txt b/glew/auto/EGL-Registry/extensions/NV/EGL_NV_stream_sync.txt new file mode 100644 index 0000000..5604c4d --- /dev/null +++ b/glew/auto/EGL-Registry/extensions/NV/EGL_NV_stream_sync.txt @@ -0,0 +1,198 @@ +Name + + NV_stream_sync + +Name Strings + + EGL_NV_stream_sync + +Contributors + + Acorn Pooley + Marcus Lorentzon + +Contacts + + Ian Stewart, NVIDIA (istewart 'at' nvidia.com) + +Status + + Complete + +Version + + Version 6, June 5, 2012 + +Number + + EGL Extension #56 + +Dependencies + + Requires EGL 1.2. + Requires EGL_KHR_stream extension + Requires EGL_KHR_reusable_sync + + This extension is written based on the wording of the EGL 1.2 + specification. + +Overview + + This extension defines a new type of reusable sync object. This + sync object will be signaled each time a new image frame becomes + available in an EGLStream for the consumer to consume. + +New functions + + EGLSyncKHR eglCreateStreamSyncNV( + EGLDisplay dpy, + EGLStreamKHR stream, + EGLenum type, + const EGLint *attrib_list); + +New Tokens + + Accepted by the <type> parameter of eglCreateSyncKHR, and returned + in <value> when eglGetSyncAttribKHR is called with <attribute> + EGL_SYNC_TYPE_KHR: + + EGL_SYNC_NEW_FRAME_NV 0x321F + + +Add a new paragraph to section "3.8.1 Sync Objects" in the +EGL_KHR_reusable_sync extension, just before the paragraph that +mentions the eglClientWaitSyncKHR function: + + The command + + EGLSyncKHR eglCreateStreamSyncNV( + EGLDisplay dpy, + EGLStreamKHR stream, + EGLenum type, + const EGLint *attrib_list); + + creates a sync object of the specified <type> associated with the + specified display <dpy> and the specified EGLStream <stream>, and + returns a handle to the new object. <attrib_list> is an + attribute-value list specifying other attributes of the sync + object, terminated by an attribute entry EGL_NONE. Attributes not + specified in the list will be assigned their default values. The + state of <stream> must not be EGL_STREAM_STATE_CREATED_KHR or + EGL_STREAM_STATE_DISCONNECTED_KHR. + + If <type> is EGL_SYNC_NEW_FRAME_NV, a stream-new-frame reusable + sync object is created. In this case <attrib_list> must be NULL or + empty (containing only EGL_NONE). Attributes of the reusable + stream-new-frame sync object are set as follows: + + Attribute Name Initial Attribute Value(s) + --------------- -------------------------- + EGL_SYNC_TYPE_KHR EGL_SYNC_NEW_FRAME_NV + EGL_SYNC_STATUS_KHR EGL_UNSIGNALED_KHR + + Any time the state of <stream> transitions to + EGL_STREAM_STATE_NEW_FRAME_AVAILABLE_KHR (from any other state), + the returned stream-new-frame reusable sync object is signaled. + (This effectively means the sync object will become signaled + whenever the producer inserts a new image frame into the + EGLStream.) + + EGL does not automatically unsignal the stream-new-frame reusable + sync object. Generally applications will want to unsignal the + sync object after it has been signaled so that the availability + of the next frame can + be detected. + + Errors + ------ + + * If <dpy> is not the name of a valid, initialized EGLDisplay, + EGL_NO_SYNC_KHR is returned and an EGL_BAD_DISPLAY error is + generated. + * If <attrib_list> is neither NULL nor empty (containing only + EGL_NONE), EGL_NO_SYNC_KHR is returned and an EGL_BAD_ATTRIBUTE + error is generated. + * If <stream> is not a valid EGLStream created for <dpy>, + EGL_NO_SYNC_KHR is returned and an EGL_BAD_STREAM error is + generated. + * If <stream>'s state is EGL_STREAM_STATE_CREATED_KHR or + EGL_STREAM_STATE_DISCONNECTED_KHR then EGL_NO_SYNC_KHR is + returned and an EGL_BAD_ACCESS error is generated. + * If a sync object of <type> has already been created for + <stream> (and not destroyed), EGL_NO_SYNC_KHR is returned and + an EGL_BAD_ACCESS error is generated. + * If <type> is not a supported type of stream sync object, + EGL_NO_SYNC_KHR is returned and an EGL_BAD_ATTRIBUTE error is + generated. + +Issues + 1. Is this extension useful, or does the built in blocking + behavior of the consumer described by the + EGL_NV_stream_consumer_gltexture extension render this + un-useful? + + RESOLVED: Yes. It is useful to have a thread waiting on the + signal. + + 2. Does EGL automatically unsignal the sync object? + + RESOLVED: No. After the sync object has been signaled, it is + up to the application to unsignal it before waiting on it + again. It is important to check for the availability of + another frame by querying EGL_PRODUCER_FRAME_KHR after + unsignaling the sync object and before waiting on the sync + object to prevent a race condition. This can be done using + the following code: + + void ConsumeFrames(EGLDisplay dpy, EGLStreamKHR stream) + { + EGLuint64KHR last_frame = 0; + EGLuint64KHR new_frame = 0; + EGLSyncKHR sync; + + sync = eglCreateStreamSyncNV(dpy, + stream, + EGL_SYNC_NEW_FRAME_NV, + 0); + + for(;;) { + eglSignalSyncKHR(dpy, sync, EGL_UNSIGNALED_KHR); + eglQueryStreamu64KHR(dpy, + stream, + EGL_PRODUCER_FRAME_KHR, + &new_frame); + if (new_frame != last_frame) { + last_frame = new_frame; + ConsumeNewFrame(stream); + } else { + eglClientWaitSyncKHR(dpy, sync, 0, EGL_FOREVER_KHR); + } + } + } + +Revision History + + #7 (July 10, 2013) Jon Leech + - Fix spelling of 'signalled' -> 'signaled' and assign extension + number for publication. + + #6 (June 5, 2012) Acorn Pooley + - Add error if stream is in state EGL_STREAM_STATE_CREATED_KHR + or EGL_STREAM_STATE_DISCONNECTED_KHR when sync is created. + + #5 (September 30, 2011) Acorn Pooley + - Change eglCreateStreamSyncKHR to eglCreateStreamSyncNV + + #4 (September 28, 2011) Acorn Pooley + - Add issue 2 + - Fix return type of eglCreateStreamSyncNV + + #3 (September 27, 2011) Acorn Pooley + - Assign enum values (bug 8064) + + #2 (July 6, 2011) Acorn Pooley + - Rename EGL_KHR_image_stream to EGL_KHR_stream + + #1 (June 30, 2011) Acorn Pooley + - Initial draft + |