[FFmpeg-devel] [PATCH] lavf/vf_deinterlace_vaapi: flush queued frame in field mode

[Fu, Linjie]

> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Mark Thompson
> Sent: Wednesday, August 21, 2019 04:49
> To: ffmpeg-devel at ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH] lavf/vf_deinterlace_vaapi: flush
> queued frame in field mode
> 
> On 02/08/2019 10:53, Linjie Fu wrote:
> > Add deint_vaapi_request_frame for deinterlace_vaapi, send NULL frame
> > to flush the queued frame.
> >
> > Fix the frame drop issue in field mode:
> >
> > ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -v verbose -c:v
> > h264 -i ./input.h264 -vf 'format=nv12|vaapi,hwupload,
> >         deinterlace_vaapi=mode=bob:rate=field,hwdownload,format=nv12'
> > -pix_fmt yuv420p -f rawvideo -vsync passthrough -y dump.yuv
> >
> > Signed-off-by: Linjie Fu <linjie.fu at intel.com>
> > ---
> >  libavfilter/vf_deinterlace_vaapi.c | 46
> ++++++++++++++++++++++++++++++++------
> >  1 file changed, 39 insertions(+), 7 deletions(-)
> 
> Can you explain in more detail what the problem is here?  What frame is
> being dropped?


Would you please try this clips to see whether it could be reproduced on your side?
https://drive.google.com/open?id=11FZlT0vl_GoGjlEuihpZHgbwgVA7yGUV


$ ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -hwaccel_output_format vaapi -v verbose -c:v h264 -i ./input.h264 -vf 'hwupload,deinterlace_vaapi=mode=bob:rate=frame' -f null -

2 frames

$ ffmpeg -hwaccel vaapi -vaapi_device /dev/dri/renderD128 -hwaccel_output_format vaapi -v verbose -c:v h264 -i ./input.h264 -vf 'hwupload,deinterlace_vaapi=mode=bob:rate=field' -f null -

Before applying:
2 frames

After applying:
4 frames 

> With this patch applied, the filter always segfaults for me at the end of the
> stream when set to field rate:

This patch just sends a NULL frame to deint_vaapi_request_frame() at the end.
Since the input_frame is not NULL in the log, it's kind of weird if it triggers a segfault.

Is it possible to share the clips to reproduce this?

> $ gdb --args ./ffmpeg_g -hwaccel vaapi -hwaccel_device
> /dev/dri/renderD129 -hwaccel_output_format vaapi -i f100.mp4 -an -vf
> deinterlace_vaapi=rate=field -f null -
> ...
> Thread 1 "ffmpeg_g" received signal SIGSEGV, Segmentation fault.
> 0x0000555555755fb1 in deint_vaapi_filter_frame (inlink=0x555559092300,
> input_frame=0x555558d42000) at src/libavfilter/vf_deinterlace_vaapi.c:227
> 227                 ctx->frame_queue[current_frame_index + i + 1]->data[3];
> (gdb) bt
> #0  0x0000555555755fb1 in deint_vaapi_filter_frame (inlink=0x555559092300,
> input_frame=0x555558d42000) at src/libavfilter/vf_deinterlace_vaapi.c:227


Thanks for the response.

- linjie