Dolby Vision now possible through MP4 Mux.

[sw5163]

I'll try your ffmpeg cmd and flac.
ffmpeg -i 00003.m2ts -map 0:2 -c pcm_s32le pcm.mov

i tried:
-map 0:AUDIO_STREAM_ID -c pcm_s24be -ar 48000 -rf64 auto \path\to\audio.mov
and
-map 0:AUDIO_STREAM_ID -c pcm_s24le -ar 48000 -rf64 auto \path\to\audio.mov

On my iPad, pcm_f/s/u_16/32/64_be/le all worked.
But I don't know what -ar 48000 -rf64 auto means.
You could just test those samples, they totally work on my iPad, so should do the same on ATV.

I have some samples produced through my usually workflow. These could probably be the highest standards video on iOS devices for now. Feel free to test them:
https://drive.google.com/drive/folders/ ... sp=sharing

I'll spend some time to try lossless and atmos audio.
Does anyone know where to find a decrypted Apple lossless atmos music file?

[RESET_9999]

nop, " pcm_s32le " did not work.
@ragico will try your sample tomorrow probably.

[sofakng]

Are there any ELI5 (explain like I'm five) guides for Dolby Vision?

I've tried searching but I can't find anything really straightforward to explain RPU, MEL, FEL, etc.

[sw5163]

I'll spend some time to try lossless and atmos audio.
Does anyone know where to find a decrypted Apple lossless atmos music file?

Never mind, it turns out Apple Music can only play 2 channel lossless or Atmos one at a time.
But, I would still be happy to know where I can download Apple atmos music, thx.

The attachment 屏幕截图 2022-07-18 003804.png is no longer available

I'll keep my opinion limitation for ATV is loseless 7.1 atmos.
If there is a public way to generate this "Dolby MAT PCM Atmos"

屏幕截图 2022-07-18 003804.png (86.25 KiB) Viewed 16835 times

[sw5163]

Are there any ELI5 (explain like I'm five) guides for Dolby Vision?

I've tried searching but I can't find anything really straightforward to explain RPU, MEL, FEL, etc.

I'm very amateur, this is for reference only, it may contain mistakes.

Once upon a time, cats only use 0-255 to represent brightness of themselves. Black cat is 0 and white cat is 255. This is called SDR.

And then there is a 5-year-old cat Tom, who is a grey cat with a little blue. His color is somewhere around 255/2 in the middle. Tom likes to take selfie with his friends on his 300 nit iPhone. Since the display brightness back then were close to each other, with no more than 400 nit, it seems fine for Tom to tell himself from other cat.

But one day, Tom bought a 1000 nit Samsung tv home and started to enjoy his good old selfies. He immediately noticed he is whiter(500 nit) in the TV than himself in the mirror(250 nit). He also noticed his good old selfies are slightly darker(150 nit) in his iPhone. He became a white cat in his Samsung tv and a dark blue cat on his iPhone. What's worse, he found himself a 5000-nit glowing cat on a 10000-nit experimental monitor.

"This can't be good." he thought. So he gathered all other cats to make a new standard. They use 0 to represent 0 nit completely dark black hole cat, somewhere between 700-750 to represent 1000-nit snow-white cat, and 1023 to represent 10000-nit dazzling Apollo cat who lives on the sun. And now Tom can finally be the same grey blue cat. This is called PQ curve HDR bl(base layer).

PQ_curve_code_value_vs._luminance.jpg

As time went by, Tom gradually grows fond of those >1000 nit snow-white cats. However they all appear to be idendical white on his 1000 nit tv. He doesn't want to mess up with the Apollo cat. Thankfully, Dolby provides RPU(reference processing unit) to indicate how cats above 1000 nit should exactly display on Tom's tv and phone. (tone mapping). It also provides EL(enhancement layer) to generate even more accurate 12-bit color depth. And now Tom can know exactly which cat is which. Yet there are so many profiles and unknown specifics, Tom has to post and ask about Dolby Vision here.

In human words:
BL(base layer): an HDR10 2160p YCbCr 4:2:0 10-bit video.
Dolby Vision fall back to this when not supported.

EL(enhancement layer): an HDR10 1080p YCbCr 4:2:0 10-bit video.
Supported device use BL and EL to mux a final 4:2:2 12-bit video.

RPU(reference processing unit): To indicate how filmmaker would like the video to be separately shown on 100nitSDR/600nit/1000nit/10000nit display. (despite the actual brightness record in BL)

There are basically 4 types of Dolby Vision video:
Profile 5(streaming): ICtCp 4:2:0(?) 10-bit video + RPU.
It uses a more efficient color coding, but appear green and purple on non support device.

Profile 8.1: BL+RPU
Profile 8.4: Dolby Vision shot on iPhone, HLG BL+RPU

FEL(Full Enhancement Layer)
Profile 7 DT_DL FEL: BL in one video track, EL+RPU in another video track.
Profile 7 ST_DL FEL: BL+EL+RPU in one same video track.

MEL(Minimum Enhancement Layer)
Profile 7 MEL: BL+RPU same as 8.1 just in bluray container.

Please don't hesitate to point out my mistake!

[ragico]

I have some samples produced through my usually workflow. These could probably be the highest standards video on iOS devices for now. Feel free to test them:
https://drive.google.com/drive/folders/ ... 1qTe?usp=s

Tested your files in Atv via the native player:
Alac and Flac play in pcm 5.1
Pcm plays in pcm 7.1 and to me has the best sound quality.
My sound system is Sonos Arc + 2 surround + sub
There is no indication of atmos but the sound generated is immersive and engaging.

[RESET_9999]

ah, I know why my lpcm track didn't work on the ATV (video and lossy audio were ok).

My mp4 headers depending on my command line were:

Code: Select all

Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom)

or

Code: Select all

Format                                   : mp43
Codec ID                                 : mp43 (isom/mp43/dby1)

and only this work

Code: Select all

Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : iso4 (iso4/iso6)

I didnt know mp4box could mux a raw hevc track with the wrong profile by default (strange that it does that). I thought the mp4muxer was needed for that so I was muxing a DV mp4 with mp4box and not an HEVC file.
The only problem I see with this method is that the static MDL metadata seems messed up now.
Mastering display luminance : min: 19.6608 cd/m2, max: 4000 cd/m2
MasteringDisplay_Luminance_Original : min: 0.0050 cd/m2, max: 4000 cd/m2

Code: Select all

Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : iso4 (iso4/iso6)
File size                                : 971 MiB
Duration                                 : 2 min 0 s
Overall bit rate                         : 67.6 Mb/s
Encoded date                             : UTC 2022-07-18 13:09:41
Tagged date                              : UTC 2022-07-18 13:09:41
Writing application                      : GPAC-2.0-rev0-g418db414-master

Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : Dolby Vision, Version 1.0, dvhe.05.06, BL+RPU, HDR10 compatible / SMPTE ST 2086, HDR10 compatible / SMPTE ST 2086
Codec ID                                 : dvh1
Duration                                 : 2 min 0 s
Bit rate                                 : 55.4 Mb/s
Maximum bit rate                         : 104 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0 (Type 2)
Bit depth                                : 10 bits
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.278
Stream size                              : 795 MiB (82%)
Title                                    : hevc@GPAC2.0-rev0-g418db414-master
Encoded date                             : UTC 2022-07-18 13:09:41
Tagged date                              : UTC 2022-07-18 13:09:42
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 19.6608 cd/m2, max: 4000 cd/m2
MasteringDisplay_Luminance_Original      : min: 0.0050 cd/m2, max: 4000 cd/m2
Maximum Content Light Level              : 1203 cd/m2
Maximum Frame-Average Light Level        : 281 cd/m2
mdhd_Duration                            : 120412
Codec configuration box                  : hvcC+dvcC

[quietvoid]

The only problem I see with this method is that the static MDL metadata seems messed up now.
Mastering display luminance : min: 19.6608 cd/m2, max: 4000 cd/m2
MasteringDisplay_Luminance_Original : min: 0.0050 cd/m2, max: 4000 cd/m2

Use hdr=none when muxing.
Example:

MP4Box -add video.hevc:dv-profile=f8.hdr10:hdr=none

[RESET_9999]

thanks that worked!

I see that we can keep DVH1 with profile 8 file using mp4box... maybe we dont have to use profile 5 on the ATV ???

Code: Select all

ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : Dolby Vision, Version 1.0, dvhe.08.06, BL+RPU, HDR10 compatible / SMPTE ST 2086, HDR10 compatible
Codec ID                                 : dvh1
Duration                                 : 4 min 59 s
Bit rate                                 : 68.4 Mb/s
Maximum bit rate                         : 121 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0 (Type 2)
Bit depth                                : 10 bits
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.344
Stream size                              : 2.39 GiB (85%)
Title                                    : hevc:dv-profile=f8.hdr10:hdr=none@GPAC2.0-rev0-g418db414-master
Encoded date                             : UTC 2022-07-18 14:41:27
Tagged date                              : UTC 2022-07-18 14:41:31
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0050 cd/m2, max: 1000 cd/m2
Maximum Content Light Level              : 1000 cd/m2
Maximum Frame-Average Light Level        : 986 cd/m2
mdhd_Duration                            : 300008
Codec configuration box                  : hvcC+dvvC

[Manixx2020beyound]

thanks that worked!

I see that we can keep DVH1 with profile 8 file using mp4box... maybe we dont have to use profile 5 on the ATV ???

Code: Select all

ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5.1@High
HDR format                               : Dolby Vision, Version 1.0, dvhe.08.06, BL+RPU, HDR10 compatible / SMPTE ST 2086, HDR10 compatible
Codec ID                                 : dvh1
Duration                                 : 4 min 59 s
Bit rate                                 : 68.4 Mb/s
Maximum bit rate                         : 121 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0 (Type 2)
Bit depth                                : 10 bits
Compression mode                         : Lossy
Bits/(Pixel*Frame)                       : 0.344
Stream size                              : 2.39 GiB (85%)
Title                                    : hevc:dv-profile=f8.hdr10:hdr=none@GPAC2.0-rev0-g418db414-master
Encoded date                             : UTC 2022-07-18 14:41:27
Tagged date                              : UTC 2022-07-18 14:41:31
Color range                              : Limited
Color primaries                          : BT.2020
Transfer characteristics                 : PQ
Matrix coefficients                      : BT.2020 non-constant
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0050 cd/m2, max: 1000 cd/m2
Maximum Content Light Level              : 1000 cd/m2
Maximum Frame-Average Light Level        : 986 cd/m2
mdhd_Duration                            : 300008
Codec configuration box                  : hvcC+dvvC

Tried the 8.1 dvh1
Produced from resolve no go.
Tried that a while ago apple won’t do 8.1
Reguardless of dvh1.
But other folks should still try it just to verify.

[RESET_9999]

@ragico just tested and it's working in MP4 P8 DVH1 + LPCM audio.

sample: https://drive.google.com/file/d/1lsSQUU ... sp=sharing

so we dont have to use fake P5 on the ATV, this is great news.

Apple native player = DV with rpu working
PLEX = DV but rpu not working
Infuse = HDR10

[sw5163]

There is no indication of atmos but the sound generated is immersive and engaging.

That's expected, conversion from TrueHD/atmos to PCM lose atmos data. That's why I'm trying to find a way to get Dolby MAT PCM with object coding.

[sw5163]

ah, I know why my lpcm track didn't work on the ATV (video and lossy audio were ok).

My mp4 headers depending on my command line were:

I don't know what the mp4 headers should be, so I just let those tools to decide.

The only problem I see with this method is that the static MDL metadata seems messed up now.

What's that? Will that cause a problem in DV play? If it doesn't affect final image, I wouldn't bother to change it.

[sw5163]

@ragico just tested and it's working in MP4 P8 DVH1 + LPCM audio.

Like I posted last month

mp4box with following command can also get dolby vision to work:
mp4box -add BL_RPU.hevc -new p5.dvh1.mp4
mp4box -add BL_RPU.hevc:dv-profile=8.1 -new p8.hvc1.mp4(this doesn't work, it's a SMB bug)
mp4box -add BL_RPU.hevc:dv-profile=f8.1 -new p8.dvh1.mp4

But fake p5.dvh1 is the most stable way, it guarantee DV play.
Besides there are official release use fake p5.dvh1(those Apple TV screensaver).
And I've never seen p8 with dvh1 except from my experiment result.
So I think it's better for us to just stick to fake p5.dvh1 for now.
Also p8.dvh1 seems to let Apple think it's an HLG, video significantly darker than normal on my iPad.
p7.dvh1 play properly. Let's not make this even more complicated.

[sw5163]

Do you know a way to generate "PCM joint object coding"?
You are the professional here.
Or is there indeed no public way except in Dolby Lab they can generate that?

I think this is possible because there are sound systems can receive "PCM/atmos".
And Apple tv actually decode EAC3/atmos and re-encode to PCM/atmos to pass to sound system.
So I figure if I provide PCM/atmos that is already decoded to ATV, it will "passthrough" that, and we get lossless/atmos.