Anything wrong with encoding to 1920x1080 rather than 1920x1088?

[Ronaldinho]

I know that 1920x1080 is not a proper mod16 resolution, and I've read that 1080p is actually 1088, but I have a file that mediainfo tells me is 1920x1080i, and I just want to convert it to 1920x1080p, however handbrake changes the resolution to 1920x1088 when I import the source file...

Is there anything wrong with me just manually typing in 1920x1080 and then encoding it like that? handbrake won't let me select 1080 lines by clicking the "up/down' buttons, I have to manually type it in...

I'm just so confused by this whole "1080p is actually 1088" business...

Can someone please tell me if there is anything wrong with manually choosing 1080 over handbrake's preferred 1088?

Thanks in advance.

[jagabo]

1080 is fine. Just change the Modulus setting in Handbrake to 8.

[Ronaldinho]

Thanks Jagabo.

I know I should have asked this question a long time ago, because I've already encoded a lot of files in handbrake as 1920x1080, but I've always just left the Modulus setting at 16...


Is this bad, and if so, why?

[Ronaldinho]

In case you're wondering, here is the mediainfo for one of my encodes, and for the source file...

SOURCE FILE

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4.0
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Format settings, GOP : M=4, N=12
Codec ID : V_MPEG4/ISO/AVC
Duration : 54mn 30s
Bit rate : 11.2 Mbps
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 : Interlaced
Scan order : Top Field First
Bits/(Pixel*Frame) : 0.216
Stream size : 4.26 GiB (95%)
Default : Yes
Forced : No
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709


Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Format settings, Endianness : Big
Codec ID : A_AC3
Duration : 54mn 30s
Bit rate mode : Constant
Bit rate : 384 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Compression mode : Lossy
Delay relative to video : 24ms
Stream size : 150 MiB (3%)
Language : English
Default : Yes
Forced : No




ENCODED FILE

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : High@L4.2
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Codec ID : V_MPEG4/ISO/AVC
Duration : 54mn 30s
Bit rate : 16.0 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 50.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.154
Stream size : 5.92 GiB (96%)
Writing library : x264 core 130 r2273 b3065e6
Encoding settings : cabac=1 / ref=1 / deblock=1:0:0 / analyse=0x3:0x113 / me=hex / subme=2 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=6 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=1 / keyint=500 / keyint_min=50 / scenecut=40 / intra_refresh=0 / rc_lookahead=10 / rc=abr / mbtree=1 / bitrate=16000 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / vbv_maxrate=62500 / vbv_bufsize=78125 / nal_hrd=none / ip_ratio=1.40 / aq=1:1.00
Language : English
Default : Yes
Forced : No
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709


Audio
ID : 2
Format : AC-3
Format/Info : Audio Coding 3
Mode extension : CM (complete main)
Format settings, Endianness : Big
Codec ID : A_AC3
Duration : 54mn 30s
Bit rate mode : Constant
Bit rate : 384 Kbps
Channel(s) : 6 channels
Channel positions : Front: L C R, Side: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 16 bits
Compression mode : Lossy
Stream size : 150 MiB (2%)
Language : English
Default : Yes
Forced : No

[jagabo]

I didn't think Handbrake would let you specify a mod8 size with the Modulus set to 16. In any case, 1920x1080 is fine for h.264 video.

[Ronaldinho]

This is how I have it set for an encode that is running right now...

[Ronaldinho]

Not sure if you're interested in the above image, but, thought I'd include it anyway...

Thanks for your help

[Mephesto]

OH WOW, I didn't realize until now that 1080 is not mod16. Took me like 5 years to realize this hahahaha. It doesn't seem right though. How can 1280x720 be perfectly divisible by 16 yet 1920x1080 which is 50% larger in both directions can't?

[Ronaldinho]

OH WOW, I didn't realize until now that 1080 is not mod16. Took me like 5 years to realize this hahahaha. It doesn't seem right though. How can 1280x720 be perfectly divisible by 16 yet 1920x1080 which is 50% larger in both directions can't?

Yeah, every time I try to learn more about video editing and encoding, I end up getting more and more confused...


Why can't 1080p just simply be 1920x1080, or why couldn't they just make 1088p TVs and advertise everything as 1088p instead 1080p, if 1088 is actually 1080p...


I'm also confused as to why I've heard people say that it's better to convert 1080i to 720p, rather than 1080p. I mean, I know it wouldn't look like true 1080p, but surely it would still look better than 720p.


Maybe someone could explain?

[jagabo]

Why can't 1080p just simply be 1920x1080, or why couldn't they just make 1088p TVs and advertise everything as 1088p instead 1080p, if 1088 is actually 1080p...

MPEG family codecs work on 16x16 blocks of pixels. When a video isn't mod 16 the blocks at the edges may be padded to fill out the 16x16 blocks before compression -- so the compression routines don't have to have special cases for blocks of different sizes. At playback the codec crops away the extra padding once the frame has been decompressed. So sticking with mod16 frame sizes gives slightly more efficient compression and decompression. Since 1920x1080 is a standard frame size for broadcast TV, Blu-ray, HD-DVD, etc. all current software and hardware can deal with it.

[Ronaldinho]

Why can't 1080p just simply be 1920x1080, or why couldn't they just make 1088p TVs and advertise everything as 1088p instead 1080p, if 1088 is actually 1080p...

MPEG family codecs work on 16x16 blocks of pixels. When a video isn't mod 16 the blocks at the edges may be padded to fill out the 16x16 blocks before compression -- so the compression routines don't have to have special cases for blocks of different sizes. At playback the codec crops away the extra padding once the frame has been decompressed. So sticking with mod16 frame sizes gives slightly more efficient compression and decompression. Since 1920x1080 is a standard frame size for broadcast TV, Blu-ray, HD-DVD, etc. all current software and hardware can deal with it.

Thanks Jagabo, I'm still a little confused though...


So does that mean that even though mediainfo is telling me my source file is 1920x1080, it is actually 1920x1088? Is Mediainfo just telling me the display resolution? And when movies are encoded for blu-ray discs, are they actually encoding them to 1920x1088?


And do you think my 1920x1080 at 50fps encodes will be future-proof? This is what I'm most concerned about...

EDIT: The main reason I started this thread is because I was wondering if there was anything wrong with my 1080p50 encodes, because I often watch my encoded files on a friend's TV via USB, but they were usually 720p50 or 720p25. These encodes all played fine, but yesterday I tried playing a 1080p50 encode on his TV for the first time, and it would not play it... I'm pretty sure is TV is 1080p, but I could be wrong... I should have checked while I was there yesterday, but I didn't because I was fairly certain that it was 1080p anyway.


I'll have to double check with him next time.

[jagabo]

I'm still a little confused though...

So does that mean that even though mediainfo is telling me my source file is 1920x1080, it is actually 1920x1088?

The codec may be using 1920x1088 internally, but as far as the outside world is concerned it is 1920x1080. MedianInfo will report them as 1920x1080. Any program that plays them will see 1920x1080.

And do you think my 1920x1080 at 50fps encodes will be future-proof? This is what I'm most concerned about...

Since 1920x1080 is the standard for HDTV your videos will be future proof in terms of the frame size. 1920x1080p50 wasn't originally part of the broadcast HDTV or Blu-ray standards but more and more players are supporting it. I wouldn't worry.

[Ronaldinho]

I'm still a little confused though...

So does that mean that even though mediainfo is telling me my source file is 1920x1080, it is actually 1920x1088?

The codec may be using 1920x1088 internally, but as far as the outside world is concerned it is 1920x1080. MedianInfo will report them as 1920x1080. Any program that plays them will see 1920x1080.

And do you think my 1920x1080 at 50fps encodes will be future-proof? This is what I'm most concerned about...

Since 1920x1080 is the standard for HDTV your videos will be future proof in terms of the frame size. 1920x1080p50 wasn't originally part of the broadcast HDTV or Blu-ray standards but more and more players are supporting it. I wouldn't worry.

Okay, that makes me feel much better.


Thanks again

[Cornucopia]

1920x1080 is 16:9. 1920x1088 is NOT (if all the pixels were fully utilized on-screen). Remember, that's just under-the-hood encoding stuff. Kind of like how SAR (storage aspect ratio) is worthless as resultant spec (who gives a shit what the SAR is if the # of pixels are correct and it displays with the correct DAR). As jagabo said, 1080 encodes should be fine for h.264.

But what I don't understand is why you changed a 1080i30 (aka 1080i60) to a 1080p60? Why not leave it as is?

Scott

[Ronaldinho]

But what I don't understand is why you changed a 1080i30 (aka 1080i60) to a 1080p60? Why not leave it as is?

Scott

I prefer all my video files to be progressive, because I play them on my computer. I know there are plenty of media players that can de-interlace, but I find that converting them to progressive with a program such as handbrake, before playing them on my PC is better than getting a media player to de-interlace on playback. Just my personal preference.

[Ronaldinho]

1920x1080 is 16:9. 1920x1088 is NOT (if all the pixels were fully utilized on-screen). Remember, that's just under-the-hood encoding stuff. Kind of like how SAR (storage aspect ratio) is worthless as resultant spec (who gives a shit what the SAR is if the # of pixels are correct and it displays with the correct DAR). As jagabo said, 1080 encodes should be fine for h.264.

And thanks for that bit of information, by the way. That helps

[Brad]

How can 1280x720 be perfectly divisible by 16 yet 1920x1080 which is 50% larger in both directions can't?

How about this explanation: 1.5*16 isn't mod16. 1280 happens to be mod32 as well, and 1.5*32 is mod16, so 1.5*1280 is mod16. 720 isn't mod32.

If it were 100% larger in both directions all would be well.

[El Heggunte]

Ideally, 2048x1152 would have been better and "perfect"
The reasons why 1920x1080 was preferred must have been purely economic (reduce production costs, satisfy lazy engineers , and so on). It has everything to do with the existence of the 5:4 aspect ratio (1280x1024).