[FFmpeg-devel] Does FFplay support HEVC interlaced bitstream display?

[Hendrik Leppkes]

On Tue, Dec 1, 2015 at 1:36 PM, wm4 <nfxjfg at googlemail.com> wrote:
> On Tue, 1 Dec 2015 12:12:13 +0000
> Andy Furniss <adf.lists at gmail.com> wrote:
>
>> Fan Yingming wrote:
>> > Hi, everyone.
>> >
>> > I noticed that HEVC support interlaced field encoding, but FFplay
>> > didn't support HEVC interlaced bitstream display.
>> >
>> > We know FFplay play h264 interlaced bitstream perfectly.
>> >
>> > I'd like to know if FFplay support HEVC interlaced bitstream
>> > display. And will FFmpeg support that?
>>
>> I don't think so.
>>
>> It is possible to play hevc interlaced with ffmpeg via mpv but you'll
>> have to set up your own filter chain and possibly adjust for field order.
>>
>> I've done it on a homemade (libx265) test. libx265 only takes a certain
>> field order and expects fields, plus interlaced support is (was) flagged
>> as experimental. It did seem to work though, it was a while ago so this
>> is just a paste from notes on the playback side - basically you need to
>> weave the fields that the decoder outputs as weaved frames is what other
>> decoders output.
>>
>> mpv -fs --vf=lavfi=[tinterlace=merge,setsar=1/1,yadif=1] hevc-interl-5M.mkv
>
> Exactly the same (without the lavfi wrapper of course) should work on
> ffplay.
>
> So does this mean the HEVC decoder outputs separate fields only? This
> is really odd, although I can understand why.

The reason for that is that HEVC doesn't actually have any interlaced
coding tools, just some metadata to flag a stream as interlaced.
So an interlaced stream is just a stream of half-height frames at twice the fps.

I thought there was a patch to assemble them back into frames, though.
Maybe it was never applied.

- Hendrik