[Libav-user] using avpicture_deinterlace

[Hendrik Leppkes]

On Mon, Sep 22, 2014 at 9:00 AM, YIRAN LI <mrfun.china at gmail.com> wrote:

> Hi there,
>
> I have some questions for the deprecated  avpicture_deinterlace function
> in ffmpeg.
>
> Our program is using avpicture_deinterlace to deinterlace frames. For
> every video packet, avcodec_decode_video2 is called to get a complete
> frame, and if it's interlaced_frame field is true, we can
> avpicture_deinterlace to deinterlace it.
>
> I'm not very familiar with frame interlacing/deinterlacing. But I double
> will it be possible that even for an interlaced streams, some frames read
> out are not interlaced and some others are. And for those interlaced
> frames, they may contain first field only, second field only or both
> fields.
>
> I mean avpicture_deinterlace is simple, it just reads an interlaced frame
> and outputs a deinterlaced one. I checked the code, seems its
> implementation doesn't handle those different cases I mentioned.
>
> So does avpicture_deinterlace always assume that input frame for example
> always contains 2 fields and avcodec_decode_video2 internally guarantees it
> (so that every frame decoded always contains 2 fields)
>
>
Anything in ffmpeg assumes that a frame contains both interlaced fields,
and all decoders will always output decoded video like this.

- Hendrik
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