| Message ID | 1452686611-145620-2-git-send-email-wuchengli@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, > From: Wu-Cheng Li [mailto:wuchengli@chromium.org] > Sent: Wednesday, January 13, 2016 1:04 PM > To: pawel@osciak.com; mchehab@osg.samsung.com; hverkuil@xs4all.nl; > k.debski@samsung.com; crope@iki.fi; standby24x7@gmail.com; > wuchengli@chromium.org; nicolas.dufresne@collabora.com; > ricardo.ribalda@gmail.com; ao2@ao2.it; bparrot@ti.com > Cc: linux-media@vger.kernel.org; linux-kernel@vger.kernel.org; linux- > api@vger.kernel.org > Subject: [PATCH] v4l: add V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE. > > Some drivers also need a control like > V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE to force an encoder > frame type. Add a general V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE > so the new drivers and applications can use it. Good to hear that there are new codecs to use the V4L2 codec API :) My two cents are following - when you add a control that does the same work as a driver specific control then it would be great if you modified the driver that uses the specific control to also support the newly added control. This way future applications could use the control you added for both new and old drivers. In future versions of this patch set please include modification of the s5p-mfc diver, this shouldn't be much work. Regarding the changes in the API I would like to hear also Hans Verkuil's opinion, as he was a great help when I introduced the changes in the codec API. Any comments Hans? Best wishes,
Hi Kamil, Le mercredi 13 janvier 2016 à 17:43 +0100, Kamil Debski a écrit : > Good to hear that there are new codecs to use the V4L2 codec API :) > > My two cents are following - when you add a control that does the same work > as a driver specific control then it would be great if you modified the > driver that > uses the specific control to also support the newly added control. > This way future applications could use the control you added for both new > and > old drivers. When i first notice this MFC specific control, I believed it was use to produce I-Frame only streams (rather then a toggle, to produce one key- frame on demand). So I wanted to verify the implementation to make sure what Wu-Cheng is doing make sense. Though, I found that we set: ctx->force_frame_type = ctrl->val; And never use that value anywhere else in the driver code. Hopefully I'm just missing something, but if it's not implemented, maybe it's better not to expose it. Otherwise, this may lead to hard to find streaming issues. I do hope we can add this feature though, as it's very useful feature for real time encoding. cheers, Nicolas
Hi, > From: Nicolas Dufresne [mailto:nicolas.dufresne@collabora.com] > Sent: Thursday, January 14, 2016 4:02 PM > To: Kamil Debski; 'Wu-Cheng Li'; pawel@osciak.com; > mchehab@osg.samsung.com; hverkuil@xs4all.nl; crope@iki.fi; > standby24x7@gmail.com; ricardo.ribalda@gmail.com; ao2@ao2.it; > bparrot@ti.com > Cc: linux-media@vger.kernel.org; linux-kernel@vger.kernel.org; linux- > api@vger.kernel.org > Subject: Re: [PATCH] v4l: add > V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE. > > Hi Kamil, > > Le mercredi 13 janvier 2016 à 17:43 +0100, Kamil Debski a écrit : > > Good to hear that there are new codecs to use the V4L2 codec API :) > > > > My two cents are following - when you add a control that does the same > > work as a driver specific control then it would be great if you > > modified the driver that uses the specific control to also support the > > newly added control. > > This way future applications could use the control you added for both > > new and old drivers. > > When i first notice this MFC specific control, I believed it was use to produce > I-Frame only streams (rather then a toggle, to produce one key- frame on > demand). So I wanted to verify the implementation to make sure what Wu- > Cheng is doing make sense. Though, I found that we set: > > ctx->force_frame_type = ctrl->val; > > And never use that value anywhere else in the driver code. Hopefully I'm just > missing something, but if it's not implemented, maybe it's better not to > expose it. Otherwise, this may lead to hard to find streaming issues. I do > hope we can add this feature though, as it's very useful feature for real time > encoding. Ooops, you're right. It's not implemented. I am adding Andrzej Hajda to the CC loop, he may know more about this. I think it may have been implemented in some of our development branches, but somehow did not make it into the mainline kernel. That's one thing. The other one is about your previous comment. I will quote it below, as it is in another email. > I don't like the way it's implemented. I don't know any decoder that have > a frame type forcing feature other they I-Frame. It would be much more > natural to use a toggle button control (and add more controls for other > types when needed) then trying to merge hypothetical toggles into >something that manually need to be set and disabled. I had a look into the documentation of MFC. It is possible to force two types of a frame to be coded. The one is a keyframe, the other is a not coded frame. As I understand this is a type of frame that means that image did not change from previous frame. I am sure I seen it in an MPEG4 stream in a movie trailer. The initial board with the age rating is displayed for a couple of seconds and remains static. Thus there is one I-frame and a number of non-coded frames. That is the reason why the control was implemented in MFC as a menu and not a button. Thus the question remains - is it better to leave it as a menu, or should there be two (maybe more in the future) buttons? Wu-Cheng, does your hardware also supports inserting such a non-coded frame? I can imagine that there could be hardware (in the future or some current hardware that I am not aware of other than MFC) that could support this. Best wishes,
Le jeudi 14 janvier 2016 à 18:21 +0100, Kamil Debski a écrit : > I had a look into the documentation of MFC. It is possible to force > two types of a frame to be coded. > The one is a keyframe, the other is a not coded frame. As I > understand this is a type of frame that means that image did not > change from previous frame. I am sure I seen it in an MPEG4 stream in > a movie trailer. The initial board with the age rating is displayed > for a couple of seconds and remains static. Thus there is one I-frame > and a number of non-coded frames. > > That is the reason why the control was implemented in MFC as a menu > and not a button. Thus the question remains - is it better to leave > it as a menu, or should there be two (maybe more in the future) > buttons? Then I believe we need both. Because with the menu, setting I-Frame, I would expect to only receive keyframes from now-on. While the useful feature we are looking for here, is to get the next buffer (or nearby) to be a keyframe. It's the difference between creating an I-Frame only stream and requesting a key-frame manually for recovery (RTP use case). In this end, we should probably take that time to review the features we have as we need: - A way to trigger a key frame to be produce - A way to produce a I-Frame only stream - A way to set the key-frame distance (in frames) even though this could possibly be emulated using the trigger. cheers, Nicolas
Hi, > From: Nicolas Dufresne [mailto:nicolas.dufresne@collabora.com] > Sent: Thursday, January 14, 2016 8:02 PM > To: Kamil Debski; 'Wu-Cheng Li'; pawel@osciak.com; > mchehab@osg.samsung.com; hverkuil@xs4all.nl; crope@iki.fi; > standby24x7@gmail.com; ricardo.ribalda@gmail.com; ao2@ao2.it; > bparrot@ti.com; 'Andrzej Hajda' > Cc: linux-media@vger.kernel.org; linux-kernel@vger.kernel.org; linux- > api@vger.kernel.org > Subject: Re: [PATCH] v4l: add > V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE. > > Le jeudi 14 janvier 2016 à 18:21 +0100, Kamil Debski a écrit : > > I had a look into the documentation of MFC. It is possible to force > > two types of a frame to be coded. > > The one is a keyframe, the other is a not coded frame. As I understand > > this is a type of frame that means that image did not change from > > previous frame. I am sure I seen it in an MPEG4 stream in a movie > > trailer. The initial board with the age rating is displayed for a > > couple of seconds and remains static. Thus there is one I-frame and a > > number of non-coded frames. > > > > That is the reason why the control was implemented in MFC as a menu > > and not a button. Thus the question remains - is it better to leave it > > as a menu, or should there be two (maybe more in the future) buttons? > > Then I believe we need both. Because with the menu, setting I-Frame, I > would expect to only receive keyframes from now-on. While the useful > feature we are looking for here, is to get the next buffer (or nearby) to be a > keyframe. It's the difference between creating an I-Frame only stream and > requesting a key-frame manually for recovery (RTP use case). > In this end, we should probably take that time to review the features we > have as we need: I think we had a discussion about this long, long time ago. Should it be deterministic which frame Is encoded as a key frame? Should it be the next queued frame, or the next processed frame? How to achieve this? I vaguely remember that we discussed per buffer controls on the mailing list, but I am not sure where the discussion went from there. > > - A way to trigger a key frame to be produce > - A way to produce a I-Frame only stream This control can be used to do this: - V4L2_CID_MPEG_VIDEO_GOP_SIZE (It is not well documented as I can see ;) ) + If set to 0 the encoder produces a stream with P only frames + if set to 1 the encoder produces a stream with I only frames + other values indicate the GOP size (I-frame interval) > - A way to set the key-frame distance (in frames) even though this could > possibly be emulated using the trigger. As described above V4L2_CID_MPEG_VIDEO_GOP_SIZE can be used to achieve this. > > cheers, >Nicolas Best wishes,
Le vendredi 15 janvier 2016 à 18:01 +0100, Kamil Debski a écrit : > I think we had a discussion about this long, long time ago. Should it > be > deterministic which frame Is encoded as a key frame? Should it be the > next queued frame, or the next processed frame? How to achieve this? > I vaguely remember that we discussed per buffer controls on the > mailing > list, but I am not sure where the discussion went from there. In RTP use cases (and most streaming cases), all we care is that we have a key-frame produced somewhere nearby after the request. In those cases we use P frame only stream to reduce the bandwidth and only request a key frame for recovery. This I believe that most common case. Many decoders though also offer what they called an "automatic" key frame mode. In the case of x264, there is also hints you can give to the encoder about what type of video (film, anime, etc.) so it can optimize all this. I believe this is very advance and there is no particular need for it. > > > > > - A way to trigger a key frame to be produce > > - A way to produce a I-Frame only stream > > This control can be used to do this: > - V4L2_CID_MPEG_VIDEO_GOP_SIZE (It is not well documented as I can > see ;) ) > + If set to 0 the encoder produces a stream with P only > frames > + if set to 1 the encoder produces a stream with I only > frames > + other values indicate the GOP size (I-frame interval) > > > - A way to set the key-frame distance (in frames) even though this > could > > possibly be emulated using the trigger. > > As described above V4L2_CID_MPEG_VIDEO_GOP_SIZE can be used to > achieve this. Great, my memory failed on me, should have checked. This is exactly what I was thinking. So Wu-Cheng Li patch is really what we need in the immediate. regards, Nicolas
diff --git a/Documentation/DocBook/media/v4l/controls.xml b/Documentation/DocBook/media/v4l/controls.xml index f13a429..326947c 100644 --- a/Documentation/DocBook/media/v4l/controls.xml +++ b/Documentation/DocBook/media/v4l/controls.xml @@ -2330,6 +2330,29 @@ vertical search range for motion estimation module in video encoder.</entry> </row> <row><entry></entry></row> + <row id="v4l2-mpeg-video-force-frame-type"> + <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE</constant> </entry> + <entry>enum v4l2_mpeg_video_force_frame_type</entry> + </row> + <row><entry spanname="descr">Force a frame type for the next queued buffer. Applicable to encoders. +This is a general, codec-agnostic keyframe control. This is a write-only and execute-on-write control. Possible values are:</entry> + </row> + <row> + <entrytbl spanname="descr" cols="2"> + <tbody valign="top"> + <row> + <entry><constant>V4L2_MPEG_FORCE_FRAME_TYPE_DISABLED</constant> </entry> + <entry>Force a specific frame type disabled.</entry> + </row> + <row> + <entry><constant>V4L2_MPEG_FORCE_FRAME_TYPE_I_FRAME</constant> </entry> + <entry>Force an I-frame.</entry> + </row> + </tbody> + </entrytbl> + </row> + + <row><entry></entry></row> <row> <entry spanname="id"><constant>V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE</constant> </entry> <entry>integer</entry> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c index c9d5537..53a8f72 100644 --- a/drivers/media/v4l2-core/v4l2-ctrls.c +++ b/drivers/media/v4l2-core/v4l2-ctrls.c @@ -315,6 +315,11 @@ const char * const *v4l2_ctrl_get_menu(u32 id) "Max Bytes", NULL, }; + static const char * const force_frame_type[] = { + "Disabled", + "I Frame", + NULL, + }; static const char * const entropy_mode[] = { "CAVLC", "CABAC", @@ -533,6 +538,8 @@ const char * const *v4l2_ctrl_get_menu(u32 id) return header_mode; case V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE: return multi_slice; + case V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE: + return force_frame_type; case V4L2_CID_MPEG_VIDEO_H264_ENTROPY_MODE: return entropy_mode; case V4L2_CID_MPEG_VIDEO_H264_LEVEL: @@ -747,6 +754,7 @@ const char *v4l2_ctrl_get_name(u32 id) case V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE: return "Horizontal MV Search Range"; case V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE: return "Vertical MV Search Range"; case V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER: return "Repeat Sequence Header"; + case V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE: return "Force an encoded frame type"; /* VPX controls */ case V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS: return "VPX Number of Partitions"; @@ -1045,6 +1053,11 @@ void v4l2_ctrl_fill(u32 id, const char **name, enum v4l2_ctrl_type *type, case V4L2_CID_DETECT_MD_MODE: *type = V4L2_CTRL_TYPE_MENU; break; + case V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE: + *type = V4L2_CTRL_TYPE_MENU; + *flags |= V4L2_CTRL_FLAG_WRITE_ONLY | + V4L2_CTRL_FLAG_EXECUTE_ON_WRITE; + break; case V4L2_CID_LINK_FREQ: *type = V4L2_CTRL_TYPE_INTEGER_MENU; break; diff --git a/include/uapi/linux/v4l2-controls.h b/include/uapi/linux/v4l2-controls.h index 2d225bc..c2be60c 100644 --- a/include/uapi/linux/v4l2-controls.h +++ b/include/uapi/linux/v4l2-controls.h @@ -390,6 +390,11 @@ enum v4l2_mpeg_video_multi_slice_mode { #define V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER (V4L2_CID_MPEG_BASE+226) #define V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (V4L2_CID_MPEG_BASE+227) #define V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (V4L2_CID_MPEG_BASE+228) +#define V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE (V4L2_CID_MPEG_BASE+229) +enum v4l2_mpeg_video_force_frame_type { + V4L2_MPEG_VIDEO_FORCE_FRAME_TYPE_DISABLED = 0, + V4L2_MPEG_VIDEO_FORCE_FRAME_TYPE_I_FRAME = 1, +}; #define V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP (V4L2_CID_MPEG_BASE+300) #define V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP (V4L2_CID_MPEG_BASE+301)
Some drivers also need a control like V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE to force an encoder frame type. Add a general V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE so the new drivers and applications can use it. Signed-off-by: Wu-Cheng Li <wuchengli@chromium.org> --- Documentation/DocBook/media/v4l/controls.xml | 23 +++++++++++++++++++++++ drivers/media/v4l2-core/v4l2-ctrls.c | 13 +++++++++++++ include/uapi/linux/v4l2-controls.h | 5 +++++ 3 files changed, 41 insertions(+)