Hi Ricardo, On Mon, Oct 7, 2019 at 6:22 PM Ricardo Ribalda Delgado <ricardo.riba...@gmail.com> wrote: > > HI Nicolas > > Sorry to hijack the thread. Do you know if anyone at AMD is working on > making a v4l driver for the encoder? Or they want to continue with > their mesa approach? > > Converting a mesa-vappi to v4l is something doable by the mortals? > Just changing the API or is a complete rewrite of the code?
Do you know what kind of hardware that is? Is it a fully integrated smart encoder that manages everything internally or a "simplified" one like Rockchip or Intel, which need a lot of assistance from the software, like bitrate control and bitstream assembly? Also, is the encoder an integral part of the GPU or a distinct block that can operate independently of the GPU driver? While it should be possible to chain a V4L2 driver of the AMDGPU DRM driver, the VAAPI model is kind of established for encoders that are closely tied with the GPU. Best regards, Tomasz > > Best regards! > > On Mon, Oct 7, 2019 at 2:05 AM Nicolas Dufresne <nico...@ndufresne.ca> wrote: > > > > Le jeudi 26 septembre 2019 à 19:21 +0900, Tomasz Figa a écrit : > > > On Mon, Sep 23, 2019 at 11:13 PM Hans Verkuil <hverk...@xs4all.nl> wrote: > > > > Hi all, > > > > > > > > Since we have three separate half-day sessions for different topics I > > > > decided > > > > to split the announcement for this in three emails as well, so these > > > > things > > > > can be discussed in separate threads. > > > > > > > > All sessions are in room Terreaux VIP Lounge - Level 0. > > > > There is a maximum of 15 people. > > > > > > > > The first session deals with the codec API and is on Tuesday morning > > > > from > > > > 8:30 (tentative, might change) to 12:00 (we have to vacate the room at > > > > that > > > > time). > > > > > > > > Confirmed attendees for this session: > > > > > > > > Boris Brezillon <boris.brezil...@collabora.com> > > > > Alexandre Courbot <acour...@chromium.org> > > > > Nicolas Dufresne <nico...@ndufresne.ca> > > > > Tomasz Figa <tf...@chromium.org> > > > > Ezequiel Garcia <ezequ...@collabora.com> > > > > Daniel Gomez <dan...@qtec.com> > > > > Dafna Hirschfeld <dafna.hirschf...@collabora.com> > > > > Eugen Hristev <eugen.hris...@microchip.com> > > > > Paul Kocialkowski <paul.kocialkow...@bootlin.com> > > > > Helen Koike <helen.ko...@collabora.com> > > > > Michael Tretter <m.tret...@pengutronix.de> > > > > Hans Verkuil <hverk...@xs4all.nl> > > > > > > > > Tentative: > > > > > > > > Laurent Pinchart <laurent.pinch...@ideasonboard.com> > > > > Jacopo Mondi <jac...@jmondi.org> > > > > > > > > Jacopo, please confirm if you want to attend this session. I didn't find > > > > an email with explicit confirmation, so it was probably done via irc. > > > > But since > > > > this session is getting close to capacity I would prefer to keep > > > > attendance to > > > > those are actually working with codecs (or will work with it in the > > > > near future). > > > > > > > > If I missed someone, or you are on the list but won't attend after all, > > > > then > > > > please let me know. > > > > > > > > > > > > > > > > Agenda: > > > > > > > > - Status of any pending patches related to codec support. > > > > > > > > - Requirements of moving codec drivers out of staging. > > > > > > > > - Finalize the stateful encoder API. There are two pieces that need > > > > to be defined: > > > > > > > > 1) Setting the frame rate so bitrate control can make sense, since > > > > they need to know this information. This is also relevant for the > > > > stateless codec (and this may have to change on a per-frame basis > > > > for stateless codecs!). > > > > > > > > This can either be implemented via ENUM_FRAMEINTERVALS for the coded > > > > pixelformats and S_PARM support, or we just add a new control for > > > > this. > > > > E.g. V4L2_CID_MPEG_VIDEO_FRAME_INTERVAL (or perhaps FRAME_RATE). If > > > > we > > > > go for a control, then we need to consider the unit. We can use a > > > > fraction as well. See this series that puts in the foundation for > > > > that: > > > > https://patchwork.linuxtv.org/cover/58857/ > > > > > > > > I am inclined to go with a control, since the semantics don't really > > > > match ENUM_FRAMEINTERVALS/S_PARM. These ioctls still need to be > > > > supported > > > > for legacy drivers. Open question: some drivers (mediatek, hva, coda) > > > > require S_PARM(OUTPUT), some (venus) allow both S_PARM(CAPTURE) and > > > > S_PARM(OUTPUT). I am inclined to allow both since this is not a > > > > CAPTURE > > > > vs OUTPUT thing, it is global to both queues. > > > > > > > > 2) Interactions between OUTPUT and CAPTURE formats. > > > > > > > > The main problem is what to do if the capture sizeimage is too small > > > > for the OUTPUT resolution when streaming starts. > > > > > > > > Proposal: width and height of S_FMT(OUTPUT) are used to > > > > calculate a minimum sizeimage (app may request more). This is > > > > driver-specific. (Is it? Or is this codec-specific?) > > > > > > > > V4L2_FMT_FLAG_FIXED_RESOLUTION is always set for codec formats > > > > for the encoder (i.e. we don't support mid-stream resolution > > > > changes for now) and V4L2_EVENT_SOURCE_CHANGE is not > > > > supported. See https://patchwork.linuxtv.org/patch/56478/ for > > > > the patch adding this flag. > > > > > > > > Of course, if we start to support mid-stream resolution > > > > changes (or other changes that require a source change event), > > > > then this flag should be dropped by the encoder driver and > > > > documentation on how to handle the source change event should > > > > be documented in the encoder spec. I prefer to postpone this > > > > until we have an encoder than can actually do mid-stream > > > > resolution changes. > > > > > > > > If sizeimage of the OUTPUT is too small for the CAPTURE > > > > resolution and V4L2_EVENT_SOURCE_CHANGE is not supported, > > > > then the second STREAMON (either CAPTURE or OUTPUT) will > > > > return -ENOMEM since there is not enough memory to do the > > > > encode. > > > > > > > > If V4L2_FMT_FLAG_FIXED_RESOLUTION is set (i.e. that should > > > > be the case for all current encoders), then any bitrate controls > > > > will be limited in range to what the current state (CAPTURE and > > > > OUTPUT formats and frame rate) supports. > > > > > > > > - Stateless encoders? > > > > > > This could indeed be a good topic. The hantro driver currently only > > > supports JPEG encoding, but the hardware also supports H.264 and VP8 > > > at least. It, however, handles only the core parts of the encoding, > > > i.e. generating the actual encoded frames (slices) without headers. It > > > also doesn't do any bitrate control or scene change detection on its > > > own and expects quality parameters (QP) or keyframe requests to come > > > from the software. > > > > > > I'm not sure if there is any other hardware with similar constraints > > > that could use V4L2, but I believe the Intel video encoder supported > > > by VAAPI has a similar design. > > > > I'll try to gather some information next week about that to prepare a > > little. As of now, we have the Rockchip mpp library and the ChromeOS > > version (which is reusing the previous one code). Then the Intel and > > AMD VAAPI drivers (which is implemented in FFMPEG and GStreamer). > > > > Maybe Paul can provide some known information about the CEDRUS (if > > any), even though this is probably harder to gather. We can also study > > software encoders like OpenH264, x264, libvpx etc. to see if there is a > > trend of parameters between the state manager and the low level > > encoders. > > > > Overall goal are, I believe (draft): > > - Find out if there is a common set of per frame encoding parameter > > - Find out if bitrate control can be reused for multiple HW > > - Decide if we do in-kernel bitrate control or not > > - Decide if we keep bitstream header crafting external (unlike Hantro > > JPEG encoder. but like VAAPI) > > - Decide if we provide (and maintain) a libv4l2 plugin like ChromeOS > > folks opted for. > > > > > > > > Best regards, > > > Tomasz > > > > > > > - Anything else? (I have a feeling I missed a codec-related topic, but > > > > I can't find it in my mailbox) > > > > > > > > Regards, > > > > > > > > Hans > > > > > -- > Ricardo Ribalda
