[FFmpeg-devel] [PATCH 14/14] videotoolbox: remove opengl compatibility attribute

[Wang Bin]

2017-12-16 2:52 GMT+08:00 wm4 <nfxjfg at googlemail.com>:
> On Fri, 15 Dec 2017 15:02:44 +0800
> wbsecg1 at gmail.com wrote:
>
>> From: wang-bin <wbsecg1 at 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