2017-12-16 15:33 GMT+08:00 Xiaolei Yu <dreifachst...@gmail.com>: > On 12/16/2017 02:07 PM, Wang Bin wrote: >> 2017-12-16 2:52 GMT+08:00 wm4 <nfx...@googlemail.com>: >>> On Fri, 15 Dec 2017 15:02:44 +0800 >>> wbse...@gmail.com wrote: >>> >>>> From: wang-bin <wbse...@gmail.com> >>>> >>>> 1. a cvpixelbuffer backed by iosurface can always be converted to an >>>> opengl texture, using CGLTexImageIOSurface2D for macOS, and undocumented >>>> api texImageIOSurface(which is internally used by public api >>>> CVOpenGLESTextureCacheCreateTextureFromImage) for iOS4.0+. >>>> 2. enabling the attribute can slow down decoding speed a lot. I tested >>>> many video clips on my macbook air. for example: ffmpeg -ss 00:00:00 -t >>>> 00:03:00 -hwaccel videotoolbox -an -i big_buck_bunny_1080p_h264.mov -f >>>> null ->/dev/null, result with the attribute >>>> enabled: frame= 2082 fps= 85 q=-0.0 Lsize=N/A time=00:03:00.00 bitrate=N/A >>>> speed=7.34x >>>> disabled: frame= 2031 fps=104 q=-0.0 Lsize=N/A time=00:03:00.00 >>>> bitrate=N/A speed=9.22x >>>> --- >>>> libavcodec/videotoolbox.c | 5 ----- >>>> 1 file changed, 5 deletions(-) >>>> >>>> diff --git a/libavcodec/videotoolbox.c b/libavcodec/videotoolbox.c >>>> index 9d2f0afa20..24631684d7 100644 >>>> --- a/libavcodec/videotoolbox.c >>>> +++ b/libavcodec/videotoolbox.c >>>> @@ -664,11 +664,6 @@ static CFDictionaryRef >>>> videotoolbox_buffer_attributes_create(int width, >>>> CFDictionarySetValue(buffer_attributes, >>>> kCVPixelBufferIOSurfacePropertiesKey, io_surface_properties); >>>> CFDictionarySetValue(buffer_attributes, kCVPixelBufferWidthKey, w); >>>> CFDictionarySetValue(buffer_attributes, kCVPixelBufferHeightKey, h); >>>> -#if TARGET_OS_IPHONE >>>> - CFDictionarySetValue(buffer_attributes, >>>> kCVPixelBufferOpenGLESCompatibilityKey, kCFBooleanTrue); >>>> -#else >>>> - CFDictionarySetValue(buffer_attributes, >>>> kCVPixelBufferIOSurfaceOpenGLTextureCompatibilityKey, kCFBooleanTrue); >>>> -#endif >>>> >>>> CFRelease(io_surface_properties); >>>> CFRelease(cv_pix_fmt); >>> >>> Does this have a negative effect on compatibility or performance? (In >>> both cases I'm asking about the case when actually using GL rendering.) >> >> Disabling the attribute improves performance in my tests. I can not >> find any document about these keys. What i know is the decoded >> cvpixelbuffer is backed by iosurface, and the api to create texture >> from iosurface is available since macOS10.6 > > Maybe you can add a flag to make them optional? > They are documented at: > https://developer.apple.com/documentation/corevideo/kcvpixelbufferopenglescompatibilitykey > https://developer.apple.com/documentation/corevideo/kcvpixelbufferiosurfaceopengltexturecompatibilitykey > > Things may still work without them but I would like to follow the > documentation whenever possible. And I think iOS DOES require the flag for > those buffers to be consumed through GLES. >
Your links explain nothing. iOS does not need it as mentioned in the patch. I tested on iphone4s+iOS9 and some new devices. > Pure speculation here. GPU texture units usually require special memory > layouts that may be suboptimal for the decoder. When these constraints are > not met either the driver has to perform the conversion or you pay the > penalty at access time. Not sure about memory layout. The fact is on mac the performance is much better without it. No difference on ios. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
