1080i50 to 1080p25

[FLX90]

Hello everybody,

I have ripped a BluRay (TV-production) which is 1080i50 and I want it to be 1080p25.

It was MBAFF encoded.

Is this losslessly possible?
And can someone please confirm that it is actually interlaced?

Example: https://ufile.io/fkphs



Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.1
Format settings : CABAC / 4 Ref Frames
Format settings, CABAC : Yes
Format settings, RefFrames : 4 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 1 min 0 s
Bit rate mode : Variable
Maximum bit rate : 33.0 Mb/s
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : MBAFF
Scan type, store method : Interleaved fields
Scan order : Top Field First
Default : Yes
Forced : No


Thank you very much.

Best
Felix

[Atak_Snajpera]

Why do you have to get rid half of the frames?

[sneaker_ger]

The sample, albeit MBAFF encoded, is progressive, not interlaced.

[Atak_Snajpera]

Indeed. Both fields refer to the same frame. No idea why they keep doing this. After all 1920x1080@25 is blu-ray compatible.
https://en.wikipedia.org/wiki/Blu-ray

[sneaker_ger]

"Real" 1080p25 encoding is only allowed on UltraHD Blu-Ray with HEVC codec. On "normal" Blu-Ray only 1080i25 is allowed but you can e.g. encode all frames/blocks as progressive (x264 has "fake interlaced" mode for that).

https://forum.doom9.org/showthread.php?t=154533

[FLX90]

The sample, albeit MBAFF encoded, is progressive, not interlaced.
Thank you.


Indeed. Both fields refer to the same frame. No idea why they keep doing this. After all 1920x1080@25 is blu-ray compatible.
https://en.wikipedia.org/wiki/Blu-ray
I don't know.
But maybe because it is originally a TV production.

Is it possible to get 1080p25 without the need of a re-encode?

[Atak_Snajpera]

Is it possible to get 1080p25 without the need of a re-encode?
But Why do you need this? Your source is in practice progressive 25fps.

[FLX90]

But Why do you need this? Your source is in practice progressive 25fps.


The playing device I'm using is a bit buggy.
It doesn't play this source.

[FLX90]

"Real" 1080p25 encoding is only allowed on UltraHD Blu-Ray with HEVC codec. On "normal" Blu-Ray only 1080i25 is allowed but you can e.g. encode all frames/blocks as progressive (x264 has "fake interlaced" mode for that).

https://forum.doom9.org/showthread.php?t=154533

Don't saw your post.

Okay thanks, so I will re-encode with x264.

[FLX90]

I get this warning
x264 [warning]: input appears to be interlaced, enabling tff interlaced mode. If you want otherwise, use --no-interlaced or --bff
x264 [warning]: interlace + weightp is not implemented

Is this the correct way?
x264-r2935-545de2f.exe --fps 25 --force-cfr --bitrate 22956 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 25 --open-gop --slices 4 --fake-interlaced --no-interlaced --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 1 -o temp.mkv output.mkv
x264-r2935-545de2f.exe --fps 25 --force-cfr --bitrate 22956 --preset veryslow --tune film --bluray-compat --vbv-maxrate 40000 --vbv-bufsize 30000 --level 4.1 --keyint 25 --open-gop --slices 4 --fake-interlaced --no-interlaced --colorprim "bt709" --transfer "bt709" --colormatrix "bt709" --sar 1:1 --pass 2 -o temp.mkv output.mkv

[sneaker_ger]

If you wanted to author a "professional" Blu-Ray (and used .264 output) that would be the correct way.

Will this solve the problem with your picky player? I don't know. The source was probably already Blu-Ray compliant (since it was a commercial Blu-Ray, right?) so maybe your player has a different problem. E.g. the sound or something with the muxing.

[benwaggoner]

I suspect that an adequately bored and knowledgeable engineer could do this as a sort of low-level remux. Using MBAFF, each frame should be fully progressive macroblocks. All the predictions will also be progressive. If the data got copied over, leaving out all the "this could be interlaced" flags, I think it would work. CABAC would need to be regenerated. I've not heard of any tools like this, however.

[FranceBB]

If you wanted to author a "professional" Blu-Ray (and used .264 output) that would be the correct way.

Yep. And FLX90 is actually lucky to have an MBAFF with only progressive frames inside. I too generally encode progressive contents as progressive flagged as interlaced, however some of my colleagues duplicate 25fps progressive to 50 progressive, divide in fields and make a "truly" interlaced content 25i.
It's not very likely to find official releases encoded that way, but it can happen...

[kolak]

... however some of my colleagues duplicate 25fps progressive to 50 progressive, divide in fields and make a "truly" interlaced content 25i.

Why would you do this? Ih has only bad side effects and basically none positive one. At least for me.

[SeeMoreDigital]

....however some of my colleagues duplicate 25fps progressive to 50 progressive...Why would you do this? Ih has only bad side effects and basically none positive one. At least for me.I seem to remember that the early Panasonic (1920x)1080p50 AVCHD camcorders generated encoded 'repeat' (or duplicate) frames instead of actual unique frames. Other manufacturers created p50 encodes using repeat flags...

[Sharc]

Why would you do this? Ih has only bad side effects and basically none positive one. At least for me.
I think the only reason is to fool picky HW players which would reject anything which is not blu-ray compliant.

[SeeMoreDigital]

Why would you do this? Ih has only bad side effects and basically none positive one. At least for me.I think the only reason is to fool picky HW players which would reject anything which is not blu-ray compliant.This is why it was better to buy a Blu-ray player that supported AVCHD media as well...

[mkver]

I think the only reason is to fool picky HW players which would reject anything which is not blu-ray compliant.
But even in this case, encoding like --face-interlaced (i.e. not to set the frame_mbs_only and mb_adaptive_frame_field_flag flags in the SPS and to encode every picture as a frame) would be the better option. But probably there was no software to do this and/or the people authoring the Blurays didn't know about this.

[kolak]

I think the only reason is to fool picky HW players which would reject anything which is not blu-ray compliant.

For that you just encode with interlace flagging. There is no need to make content really interlaced.

[kolak]

But even in this case, encoding like --face-interlaced (i.e. not to set the frame_mbs_only and mb_adaptive_frame_field_flag flags in the SPS and to encode every picture as a frame) would be the better option. But probably there was no software to do this and/or the people authoring the Blurays didn't know about this.

Good BD encoders allow for it. I done 100+ projects this way.

[Sharc]

For that you just encode with interlace flagging. There is no need to make content really interlaced.
Sure. I just remember cases from the early days of DVD where "pseudo-interlaced" was created by phase shifting fields, means taking the top field from the current frame and the bottom field from the next frame of a progressive source. It didn't look nice when throwing a deinterlacer at such footage instead of matching the fields to restore the original progressive frames. Interestingly, such material was even proposed for testing deinterlacers.