[FFmpeg-devel] [RFC] interlace flagging and detecting.

[Michael Niedermayer]

On Tue, Oct 09, 2012 at 03:52:50PM +0100, Tim Nicholson wrote:
> I am trying to tie up some loose ends in the interlace flagging within
> ffmpeg brought to light by attempting to sort out the missing, but
> mandatory 'fiel' atom in uncompressed quicktimes.
> 
> I could do with some confirmation from those more familiar that I am on
> the right track.
> 
> From what I have gleaned by poring over the code, ffmpeg and libraries
> principally use the AVFrame struct 'interlaced_frame' and
> 'top_field_first' flags, although there is also AVCodecContext's
> field_order enum which seems to exist in order to cover the flag
> permutations required by the qt fiel atom. AFAIK currently these two are
> completely independent. I can find no code to link them or use one if
> the other is blank.
>

> For example, a sample uncompressed 2vuy .mov when inspected by 'ffprobe
> -show_frames' has interlaced_frame and top_field_first = 0 whilst the
> 'fiel' atom indicates interlaced/bottom field first.

thats a bug, the decoder should read the field_order from the context
and fill it in the AVFrames it returns


[...]
> I notice also that although many codecs seems to access the AVFrame
> 'interlaced_frame' for making decisions about interlace handling the

yes


> Avid Meridien coder (avuienc.c) specifically uses AVCodecContext's
> field_order, so there does seem to be some inconsistency.

are there other raw encoders that need interlaced info at init time ?
if not then its not really inconsistent.
non raw encoders take the interlaced info from user specified
parameters normally ...


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If you think the mosad wants you dead since a long time then you are either
wrong or dead since a long time.
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