Deinterlacing problems

[Ozzapoo]

Hi. I have some interlaced video that I captured from my VCR. After doing some simple joining/splitting in Premiere and exporting as an interlaced video, Windows Media Player won't automatically deinterlace it, whereas it did with the original uncompressed AVI. VLC, however, is able to deinterlace the new file. What is causing this, and how can I fix it?

[enim]

I do have a similar problem, I am on Linux and I use VLC like anything. I have a deinterlaced AVI file which I want to convert it to interlaced to be viewed on stand-alone. Any idea?

In your case direct show decoder like ffdshow with built-in deinterlacer will help for sure.

May be all gurus ZZZZzzzzzz already!

[hello_hello]

I don't have a definitive answer to the first question. Video must be flagged as interlaced in order for it to be de-interlaced during the playback process. Your video card would probably do it normally. However video can be de-interlaced using software. VLC's de-interlacer may be permanently enabled, although it appears to be disabled by default. Maybe upload a small video sample.

enim,
Why convert it to interlaced? AVI capable players such as DVD players should be fine playing progressive video. Even DVD video can be progressive. The x264 encoder has a fake interlaced setting to make PAL/NTSC encodes Bluray compliant. http://mewiki.project357.com/wiki/X264_Settings#fake-interlaced

[Ozzapoo]

I've attached a 1 second sample of the exported video from Premiere. This is what MediaInfo says about it:

General
Complete name                            : Sequence 03.mp4
Format                                   : MPEG-4
Format profile                           : Base Media / Version 2
Codec ID                                 : mp42
File size                                : 499 KiB
Duration                                 : 1s 0ms
Overall bit rate mode                    : Variable
Overall bit rate                         : 4 084 Kbps
Encoded date                             : UTC 2014-01-28 11:34:54
Tagged date                              : UTC 2014-01-28 11:34:54
©TIM                                     : 00:00:00:00
©TSC                                     : 25
©TSZ                                     : 1

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : Main@L3.1
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 3 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 1s 0ms
Bit rate mode                            : Variable
Bit rate                                 : 3 814 Kbps
Maximum bit rate                         : 6 000 Kbps
Width                                    : 720 pixels
Height                                   : 576 pixels
Display aspect ratio                     : 4:3
Original display aspect ratio            : 4:3
Frame rate mode                          : Constant
Frame rate                               : 25.000 fps
Standard                                 : PAL
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Interlaced
Scan order                               : Bottom Field First
Bits/(Pixel*Frame)                       : 0.368
Stream size                              : 466 KiB (93%)
Language                                 : English
Encoded date                             : UTC 2014-01-28 11:34:54
Tagged date                              : UTC 2014-01-28 11:34:54

Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 1s 0ms
Source duration                          : 1s 45ms
Bit rate mode                            : Variable
Bit rate                                 : 192 Kbps
Maximum bit rate                         : 196 Kbps
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 48.0 KHz
Compression mode                         : Lossy
Stream size                              : 23.2 KiB (5%)
Source stream size                       : 24.2 KiB (5%)
Language                                 : English
Encoded date                             : UTC 2014-01-28 11:34:54
Tagged date                              : UTC 2014-01-28 11:34:54

Note that it is flagged as interlaced and you can quite clearly see that it is. If you turn enable deinterlacing in VLC it deinterlaces as expected, but Windows Media Player does not do this, whereas it did do this with the original. I'm trying to figure out why WMP isn't deinterlacing automatically. Here is the MediaInfo output for the original which, by the way, doesn't mention its scan type:

General
Complete name                            : D:\Recorded Media\2_0.avi
Format                                   : AVI
Format/Info                              : Audio Video Interleave
Format profile                           : OpenDML
File size                                : 16.4 GiB
Duration                                 : 13mn 52s
Overall bit rate                         : 169 Mbps

Video
ID                                       : 0
Format                                   : YUV
Codec ID                                 : YUY2
Codec ID/Info                            : YUV 4:2:2 as for UYVY but with different component ordering within the u_int32 macropixel
Duration                                 : 13mn 52s
Bit rate                                 : 166 Mbps
Width                                    : 720 pixels
Height                                   : 576 pixels
Display aspect ratio                     : 5:4
Frame rate                               : 25.000 fps
Standard                                 : PAL
Color space                              : YUV
Chroma subsampling                       : 4:2:2
Compression mode                         : Lossless
Bits/(Pixel*Frame)                       : 15.990
Stream size                              : 16.1 GiB (98%)

Audio
ID                                       : 1
Format                                   : PCM
Format settings, Endianness              : Little
Format settings, Sign                    : Signed
Codec ID                                 : 1
Duration                                 : 13mn 52s
Bit rate mode                            : Constant
Bit rate                                 : 3 072 Kbps
Channel(s)                               : 2 channels
Sampling rate                            : 96.0 KHz
Bit depth                                : 16 bits
Stream size                              : 305 MiB (2%)
Alignment                                : Aligned on interleaves
Interleave, duration                     : 42 ms (1.04 video frame)

[hello_hello]

I don't have the answer. Maybe someone more experienced with interlaced h264 video may come along. I never encode interlaced myself.

I can tell you I tried the sample with MPC-HC. When it's internal filters where used for decoding (LAV filters) the video was de-interlaced. When I switched to ffdshow it wasn't.
Both LAV and ffdshow have de-interlacing set to auto. I don't think they de-interlace themselves (ffdshow definitely doesn't unless it's own de-interlacing is enabled). "Auto" for them just means the interlaced flag gets passed on to the next filter. If I set ffdshow to force an interlaced flag the video is de-interlaced, but not when using auto.

VLC 2.06 (reset to default settings so it's software de-interlacing is disabled) displayed the video without it being de-interlaced. As I had an older version of VLC, I upgraded VLC to 2.1.2 and tried again. It still wasn't de-interlaced.

I didn't bother trying WMP as the version I have is so old it wouldn't be relevant.

My "theory" is this. Normally for the video to be automatically de-interlaced, the interlaced flag needs to be passed along to the renderer or video card.... wherever the de-interlacing is done. Mostly, for your sample that doesn't seem to be happening. I'm not sure why.
When you enable de-interlacing in VLC is uses it's own de-interlacing, but I still couldn't get it to de-interlace your sample with de-interlacing set to "auto" (where it should only de-interlace frames flagged as interlaced). In order to get VLC to de-interlace it, you have to set de-interlacing to "on" which I assume just forces de-interlacing for everything. It's probably not a good idea to set it to "on" as a general rule as it'd de-interlace progressive video too, which will probably blur fine detail. WMP probably doesn't have it's own de-interlacer and relies on the frames being flagged as interlaced and de-interlaced by the hardware etc. So it's probably a lot harder to "force" de-interlacing when using WMP.

I did a little research and I'm running out of time to keep playing around now, but it seems there's two ways to encode interlaced h264 video.
http://www.afterdawn.com/glossary/term.cfm/picture-level_frame-field_coding
http://www.afterdawn.com/glossary/term.cfm/macroblock-adaptive_frame-field_coding

The x264 encoder only supports the latter. When I ran a little test interlaced encode (my first interlaced encode ever, I think) instead of reporting the Scan Type as interlaced, MediaInfo reported it as Scan type : MBAFF.
The resulting encode was de-interlaced properly when I used MPC-HC with the LAV decoder, and also when I used MPC-HC with ffdshow.
VLC with it's internal de-interlacer disabled, displayed the video without it being de-interlaced. Seems like VLC doesn't pass the interlaced flag on to the next filter in the chain. The "auto" de-interlacing setting got VLC to de-interlace it. There was no need to set de-interlacing to "on" and force the video to be de-interlaced.

I'll go out on a limb and assume if MediaInfo reports the scan type as being interlaced, then PicAFF encoding is used (not MBAFF). If that's the case, I don't know why most decoders don't seem to understand your video is interlaced. For me, ffdshow and VLC don't. You have to force the interlaced flag in ffdshow's case, or set de-interlacing to "on" for VLC to force it. In either case "auto" treats it as progressive.

The x264 encoder doesn't support PicAFF encoding so I'd have to research encoding that way..... to see if it's the encoding method or something else causing the problem.

There's a list of encoders here and the type of interlaced encoding they support. Does Premier use one of those? Maybe you could even choose the interlaced encoding method?
(Edit. Fixed the link) http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC#Software_encoder_feature_comparison

Sorry I still haven't answered your question, re why your video isn't automatically being de-interlaced. My little MBAFF interlaced encode seems to behave ("auto" de-interlacing de-interlaces it). That's as far as I got at the moment. Hopefully the info above at least makes sense. I was typing stuff as I was reading and playing around.

PS Give this sample a spin with WMP. Or with VLC's de-interlacing set to auto.

[Ozzapoo]

Thanks for that response! I've now been able to fix my problem. As you said, it was to do with the fact that Premiere's H.264 encoder does not support interlaced encoding properly. The sample video you posted deinterlaced automatically as expected. Now, instead of encoding directly to H.264 through Premiere, I first export it and then encode using x264 with MBAFF, solving the problem. It's a shame that Premiere can't do this properly, but at least I now know the reason.

[hello_hello]

It seems odd Premiere can export it as interlaced but not encode it properly. And I'd still like to know why LAV Filters seem to understand your sample was interlaced, even if it was treated as progressive by everything else. As long as you've got it sorted though.....

Personally I'd be de-interlacing it before encoding, as then there's no issue as to whether it'll be de-interlaced on playback. If you de-interlace to "full frame rate" (ie 50fps for PAL or 59.94fps for NTSC) you won't lose any smoothness of motion.
Yadif at full frame rate seems to do just as good as job at de-interlacing as my hardware does, while QTGMC does a better job than anything else.

Just some thoughts..... each to their own, but I can't bring myself not to de-interlace with QTGMC these days as it does it so well. If you're interested, there's a little sample of interlaced video here along with encoded versions de-interlaced to 25fps and 50fps with Yadif and QTGMC. When playing the interlaced version using my PC hooked up to my TV, the de-interlacing looks pretty much the same as Yadif at 50fps.