Hi Kiran, > From: Kiran Avnd [mailto:[email protected]] > Sent: Tuesday, September 16, 2014 10:10 AM > > Hi Kamil, > > > On Mon, Sep 15, 2014 at 8:12 PM, Kamil Debski <[email protected]> > wrote: > > > Hi, > > > From: Kiran AVND [mailto:[email protected]] > > Sent: Monday, September 15, 2014 8:43 AM > > > > set default number of B-frames as 2 while encoding for better > > compression. This User can however change this setting using > > V4L2_CID_MPEG_VIDEO_B_FRAMES. > > The last sentence should be rephrased, as it is not clear. > > > > Sure. Will do. > > > The tougher question is what should be the default? > In my opinion the default should produce a stream that is as > simple as it gets. It should be playable on most hardware, > some of which may not support B frames. > > Anyway - this setting can be changed by the user to 2 using > V4L2_CID_MPEG_VIDEO_B_FRAMES ;) > > > > > Its empirical, and this setting has better compression quality and bit > rate than otherwise, in our testing.
It doesn't surprise me - introducing B frames should increase both quality and compression efficiency at the cost of computation complexity and limiting compatibility. The thing I am against is changing the driver so that it forces such value of the encoding parameter on the user. Default number of B frames should remain 0. The application should consciously choose to use B frames. Best wishes, -- Kamil Debski Samsung R&D Institute Poland > > Regards, > Kiran > > > > > > > > Signed-off-by: Kiran AVND <[email protected]> > > --- > > drivers/media/platform/s5p-mfc/s5p_mfc_enc.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > b/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > index cd1b2a2..f7a6f68 100644 > > --- a/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > +++ b/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > @@ -280,7 +280,7 @@ static struct mfc_control controls[] = { > > .minimum = 0, > > .maximum = 2, > > .step = 1, > > - .default_value = 0, > > + .default_value = 2, > > }, > > { > > .id = V4L2_CID_MPEG_VIDEO_H264_PROFILE, > > -- > > 1.7.3.rc2 > > -- > To unsubscribe from this list: send the line "unsubscribe linux- > media" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo- > info.html > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
