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SubjectRe: [PATCH 3/7] media: cedrus: Fix decoding for some H264 videos
Date
Dne ponedeljek, 03. junij 2019 ob 13:55:36 CEST je Maxime Ripard napisal(a):
> Hi,
>
> On Thu, May 30, 2019 at 11:15:12PM +0200, Jernej Skrabec wrote:
> > It seems that for some H264 videos at least one bitstream parsing
> > trigger must be called in order to be decoded correctly. There is no
> > explanation why this helps, but it was observed that two sample videos
> > with this fix are now decoded correctly and there is no regression with
> > others.
> >
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> > ---
> > I have two samples which are fixed by this:
> > http://jernej.libreelec.tv/videos/h264/test.mkv
> > http://jernej.libreelec.tv/videos/h264/Dredd%20%E2%80%93%20DTS%20Sound%20C
> > heck%20DTS-HD%20MA%207.1.m2ts
> >
> > Although second one also needs support for multi-slice frames, which is
> > not yet implemented here.>
> > .../staging/media/sunxi/cedrus/cedrus_h264.c | 22 ++++++++++++++++---
> > 1 file changed, 19 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c index
> > cc8d17f211a1..d0ee3f90ff46 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h264.c
> > @@ -6,6 +6,7 @@
> >
> > * Copyright (c) 2018 Bootlin
> > */
> >
> > +#include <linux/delay.h>
> >
> > #include <linux/types.h>
> >
> > #include <media/videobuf2-dma-contig.h>
> >
> > @@ -289,6 +290,20 @@ static void cedrus_write_pred_weight_table(struct
> > cedrus_ctx *ctx,>
> > }
> >
> > }
>
> We should have a comment here explaining why that is needed

ok.

>
> > +static void cedrus_skip_bits(struct cedrus_dev *dev, int num)
> > +{
> > + for (; num > 32; num -= 32) {
> > + cedrus_write(dev, VE_H264_TRIGGER_TYPE, 0x3 | (32 <<
8));
>
> Using defines here would be great

Yes, sorry about that.

>
> > + while (cedrus_read(dev, VE_H264_STATUS) & (1 << 8))
> > + udelay(1);
> > + }
>
> A new line here would be great
>
> > + if (num > 0) {
> > + cedrus_write(dev, VE_H264_TRIGGER_TYPE, 0x3 | (num <<
8));
> > + while (cedrus_read(dev, VE_H264_STATUS) & (1 << 8))
> > + udelay(1);
> > + }
>
> Can't we make that a bit simpler by not duplicating the loop?
>
> Something like:
>
> int current = 0;
>
> while (current < num) {
> int tmp = min(num - current, 32);
>
> cedrus_write(dev, VE_H264_TRIGGER_TYPE, 0x3 | (current << 8))
> while (...)
> ...
>
> current += tmp;
> }

Yes, that looks better, I'll change it in next version.

Best regards,
Jernej



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