[FFmpeg-devel] The log level of "co located POCs unavailable" should not be ERROR

[Michael Niedermayer]

On Sat, Mar 02, 2019 at 01:23:17PM +0800, Yukun Guo wrote:
> On Fri, 1 Mar 2019 at 05:30, Michael Niedermayer wrote:
> > When data is missing (in live streaming or otherwise) it under
> > almost all cases cannot be losslessly recovered. So this use matches
> > the definition
> 
> Yes, this is reasonable. But then "Frame num gap" should be of ERROR
> level too. H.264 standard states if there is a frame num gap, the
> decoder should infer an unintentional loss of pictures, assuming
> gaps_in_frame_num_value_allowed_flag = 0. But it is possible that
> FFmpeg encounters a frame loss but does not print any error messages,
> because the error concealment procedure
> (https://github.com/FFmpeg/FFmpeg/blob/n4.1.1/libavcodec/h264_slice.c#L1577)
> will clone the previous frame in place of the missing one.

Yes, if this ends up not printing anything then that would be unexpected


> 
> Also, regarding to the error concealment, why isn't
> `short_ref[0].field_poc` copied for cloned frames? The unset field_poc
> causes "co located POCs unavailable" error, despite
> `ref_list[1][0].poc` is valid when doing spatial direct predition.

If the frame is copied, its copy would be at a different point in time
so it may need a different poc and simply copying it might cause issues

thanks

[...]
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