[mythtv] Is AvFormatDecoder::GetFrame(-1) broken?

Boleslaw Ciesielski bolek-mythtv at curl.com
Tue Jan 10 02:43:24 UTC 2006

Boleslaw Ciesielski wrote:
> It seems that AvFormatDecoder::GetFrame(-1) is not returning after the 
> next frame but only after the entire file is read. This isn't the right 
> behavior, is it? This affects for example 
> NuppelVideoPlayer::RebuildSeekTable which does not display any progress 
> messages because of it.
> Assuming that this is wrong, I tried the following patch:
> --- libs/libmythtv/avformatdecoder.cpp  (revision 8519)
> +++ libs/libmythtv/avformatdecoder.cpp  (working copy)
> @@ -2483,6 +2483,7 @@
>                      }
>                      if (onlyvideo < 0)
>                      {
> +                        gotvideo = 1;
>                          framesPlayed++;
>                          ptr += pkt->size;
>                          len -= pkt->size;
> This fixes the problem, but I am not sure if it's right.

Does any one have comments about this? I do think this is a real bug.

AFAICT, it affects two things:

1. "mythcommflag --rebuild" does not show progress (and it does with the 
patch above). Ironically, NuppelVideoPlayer::RebuildSeekTable still 
works because all it has to do is read the entire file (which the first 
call to GetFrame(-1) does).

2. FF beyond the end of the position map seems to be affected but I am 
not sure how to provoke it. It seems that it may not work because of the 
early return:

         if (ateof)
             // Re-enable rawframe state if it was enabled before FF
             getrawframes = oldrawstate;
             return false;

ateof would be true because GetFrame(-1) read the whole file.

I could create a ticket for this but it's just a one liner and more 
importantly I am still not sure if the proposed patch is the right fix. 
Should I do it anyway?


More information about the mythtv-dev mailing list