On Wed, 2020-09-02 at 14:04 +0000, Soft Works wrote: > > -----Original Message----- > > From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of > > Rogozhkin, Dmitry V > > Sent: Wednesday, September 2, 2020 3:54 PM > > To: ffmpeg-devel@ffmpeg.org > > Subject: Re: [FFmpeg-devel] [PATCH] ffmpeg_qsv: use -hwaccel_device to > > specify a device for VAAPI backend > > > > On Wed, 2020-09-02 at 07:31 +0000, Soft Works wrote: > > > > -----Original Message----- > > > > From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On Behalf Of > > > > Rogozhkin, Dmitry V > > > > Sent: Wednesday, September 2, 2020 9:00 AM > > > > To: ffmpeg-devel@ffmpeg.org > > > > Subject: Re: [FFmpeg-devel] [PATCH] ffmpeg_qsv: use -hwaccel_device > > > > to specify a device for VAAPI backend > > > > > > > > On Wed, 2020-09-02 at 04:28 +0000, Xiang, Haihao wrote: > > > > > On Wed, 2020-09-02 at 04:20 +0000, Soft Works wrote: > > > > > > > -----Original Message----- > > > > > > > From: ffmpeg-devel <ffmpeg-devel-boun...@ffmpeg.org> On > > > > Behalf > > > > > > > > Of > > > > > > > Haihao Xiang > > > > > > > Sent: Wednesday, September 2, 2020 6:01 AM > > > > > > > To: ffmpeg-devel@ffmpeg.org > > > > > > > Cc: Haihao Xiang <haihao.xi...@intel.com> > > > > > > > Subject: [FFmpeg-devel] [PATCH] ffmpeg_qsv: use > > > > > > > -hwaccel_device to specify a device for VAAPI backend > > > > > > > > > > > > > > According to the FFmpeg documentation, -hwaccel_device can be > > > > > > > used to select a device for hardware acceleration > > > > > > > > > > > > > > Example: > > > > > > > ffmpeg -hwaccel qsv -hwaccel_device /dev/dri/renderD129 -c:v > > > > > > > h264_qsv \ -i > > > > > > > in.h264 -c:v hevc_qsv out.h265 > > > > > > > > > > > > No. The docs say about hwaccel_device > > > > > > > > > > > > It can either refer to an existing device created with > > > > > > -init_hw_device by name, > > > > > > > > > > > > => /dev/dri/renderD129 is not an existing device name > > > > > > > > > > > > or it can create a new device as if ‘-init_hw_device’ > > > > > > type:hwaccel_device were called immediately before. > > > > > > > > > > > > => /dev/dri/renderD129 is not a valid string for init_hw_device > > > > > > > > Well, it seems that's where documentation does not reflect the > > > > reality since (as pointed by Haihao below) > > > > https://trac.ffmpeg.org/wiki/Hardware/VAAPI > > > > is full of contradictory examples. > > > > > > > > > > > > > > > > > > > > > > Hence, the patch doesn't make sense. > > > > > > > > > > in https://trac.ffmpeg.org/wiki/Hardware/VAAPI, > > > > > > > > > > If only one stream is being used, -hwaccel_device can also accept > > > > > a device path directly > > > > > > > > > > ffmpeg -hwaccel vaapi -hwaccel_device /dev/dri/renderD128 -i ... > > > > > > > > > > I think it can be applied to qsv too. > > > > > > > > > > > > > I agree. Part of ffmpeg help: > > > > -hwaccel hwaccel name use HW accelerated decoding > > > > -hwaccel_device devicename select a device for HW acceleration > > > > > > > > To me specifying device via -hwaccel_device in the way it is being > > > > suggest in commit is pretty intuitive and is better than explain > > > > people that there is - qsv_device for that purpose. Niceness of > > > > -hwaccel_device is that it is not tight to particular acceleration, > > > > hence easier to work with for end users. > > > > > > In case of QSV, the usage of hwaccel_device is already defined: > > > > > > device selects a value in ‘MFX_IMPL_*’. Allowed values are: > > > auto sw hw auto_any hw_any hw2 hw3 hw4 > > > > > > I agree that it would be more intuitive, but you can't just give it a > > > different meaning from one day to another and break functionality. > > > > Adding new values does not break functionality! No one suggests to drop > > existing set of values (sw, hw, etc.) - these are remaining. But basically > > suggestion is to extend allowed set to accept drm device specification on > > Linux, that's it. Honestly, I don't see problem here. > > Some background story: hw,hw2,hw3 allows to select adapter for msdk > > library on Windows, but they don't allow to do that on Linux. On Linux all > > these hw options are basically the same for the reason that device is being > > specified externally via SetHandle call. On Linux only sw/hw makes a > > difference (other story that sw msdk library is not actually released > > currently > > on Linux). That's the origin of the request: we need a good way to specify > > adapter on Linux. > > As mentioned, there are cases where both needs to be specified on Windows: > hw, hw2, hw3,.. plus adapter number. > > 'qsv_device' is for specifying adapter number on Windows and DRI on Linux > 'hwaccel_device' is for specifying hw, hw2, hw3 (everywhere)
According to https://trac.ffmpeg.org/ticket/7649, -qsv_device was added to workaround device selection on Linux. On Windows, we should not use another option to specify the adapter number, the adapter is 1:1 mapped to the hw impl. I think we should fix it if the current QSV depends on -qsv_device on Window. https://github.com/Intel-Media-SDK/MediaSDK/blob/master/samples/sample_decode/src/pipeline_decode.cpp#L245-L264 > > I see no reason to start mixing that and allowing to specify DRI via > 'hwaccel_device' parameter. > > That would make things just worse instead of improving anything. From user's perspective, we may use the same device selection for both QSV and VAAPI on Linux. It is easy for user to move from QSV to VAAPI or inverse. > > That's how I see it. I would be really interested what others think... > > Kind regards, > softworkz > > The adapter number is specified via 'qsv_device' a > _______________________________________________ > ffmpeg-devel mailing list > ffmpeg-devel@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
