Transcoding HEVC 4K HDR using ffmpeg and vaapi

Question

I am trying to transcode a 4K HEVC HDR video to a lower bitrate using ffmpeg and VAAPI hardware acceleration for my LG OLED television.

I use the following file: Video

Using the following command:

ffmpeg -init_hw_device vaapi=va:/dev/dri/renderD128 -hwaccel vaapi -hwaccel_output_format vaapi -hwaccel_device va -filter_hw_device va -i LG\ 4K\ HDR\ Demo\ -\ Daylight.mkv -map 0:0 -t 00:00:20 -c:v hevc_vaapi -sei hdr -qp:v 21 lg_vaapi.mkv

But this file is not recognized as HDR on my TV.

When using the libx265 encoder (which is off course much slower) it works fine:

ffmpeg -i LG\ 4K\ HDR\ Demo\ -\ Daylight.mkv -t 00:00:20 -map 0:0 -c:v libx265 -preset medium -crf 18 -x265-params "colorprim=bt2020:colormatrix=bt2020nc:transfer=smpte2084:colormatrix=bt2020nc:hdr=1:info=1:repeat-headers=1:master-display=G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(11000000,40)" lg_libx265.mkv

When comparing the output of mediainfo on both files I can see the following properties are not set for the video track:

• Color range
• Color primaries
• Transfer characteristics

mediainfo for vaapi encode:

General
Unique ID                                : 168011494166392912924249315217763643529 
(0x7E65D636029A5354FE73998A5ED6B089)
Complete name                            : lg_vaapi.mkv
Format                                   : Matroska
Format version                           : Version 4
File size                                : 118 MiB
Duration                                 : 20 s 4 ms
Overall bit rate                         : 49.6 Mb/s
Writing application                      : Lavf58.20.100
Writing library                          : Lavf58.20.100
ErrorDetectionType                       : Per level 1

Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5@Main
HDR format                               : SMPTE ST 2086, HDR10 compatible
Codec ID                                 : V_MPEGH/ISO/HEVC
Duration                                 : 20 s 4 ms
Bit rate                                 : 48.6 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 59.940 (60000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Bits/(Pixel*Frame)                       : 0.098
Stream size                              : 116 MiB (98%)
Writing library                          : Lavc58.35.100 hevc_vaapi
Default                                  : Yes
Forced                                   : No
Mastering display color primaries        : Display P3
Mastering display luminance              : min: 0.0040 cd/m2, max: 1100 cd/m2

mediainfo for the libx265 encode:

General
Unique ID                                : 261605749278874425324960669956061374077 (0xC4CF6F42FE952004772A02D5819DA67D)
Complete name                            : lg_libx265.mkv
Format                                   : Matroska
Format version                           : Version 4
File size                                : 155 MiB
Duration                                 : 47 s 715 ms
Overall bit rate                         : 27.3 Mb/s
Writing application                      : Lavf58.20.100
Writing library                          : Lavf58.20.100
ErrorDetectionType                       : Per level 1

Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main [email protected]@Main
HDR format                               : SMPTE ST 2086, HDR10 compatible
Codec ID                                 : V_MPEGH/ISO/HEVC
Duration                                 : 47 s 715 ms
Bit rate                                 : 26.8 Mb/s
Width                                    : 3 840 pixels
Height                                   : 2 160 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 59.940 (60000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 10 bits
Bits/(Pixel*Frame)                       : 0.054
Stream size                              : 152 MiB (98%)
Writing library                          : x265 2.8:[Linux][GCC 9.1.0][64 bit] 10bit
Encoding settings                        : cpuid=1111039 / frame-threads=3 / wpp / no-pmode / no-pme / no-psnr / no-ssim / log-level=2 / input-csp=1 / input-res=3840x2160 / interlace=0 / total-frames=0 / level-idc=0 / high-tier=1 / uhd-bd=0 / ref=3 / no-allow-non-conformance / repeat-headers / annexb / no-aud / no-hrd / info / hash=0 / no-temporal-layers / open-gop / min-keyint=25 / keyint=250 / gop-lookahead=0 / bframes=4 / b-adapt=2 / b-pyramid / bframe-bias=0 / rc-lookahead=20 / lookahead-slices=8 / scenecut=40 / radl=0 / no-intra-refresh / ctu=64 / min-cu-size=8 / no-rect / no-amp / max-tu-size=32 / tu-inter-depth=1 / tu-intra-depth=1 / limit-tu=0 / rdoq-level=0 / dynamic-rd=0.00 / no-ssim-rd / signhide / no-tskip / nr-intra=0 / nr-inter=0 / no-constrained-intra / strong-intra-smoothing / max-merge=2 / limit-refs=3 / no-limit-modes / me=1 / subme=2 / merange=57 / temporal-mvp / weightp / no-weightb / no-analyze-src-pics / deblock=0:0 / sao / no-sao-non-deblock / rd=3 / no-early-skip / rskip / no-fast-intra / no-tskip-fast / no-cu-lossless / no-b-intra / no-splitrd-skip / rdpenalty=0 / psy-rd=2.00 / psy-rdoq=0.00 / no-rd-refine / no-lossless / cbqpoffs=0 / crqpoffs=0 / rc=crf / crf=18.0 / qcomp=0.60 / qpstep=4 / stats-write=0 / stats-read=0 / ipratio=1.40 / pbratio=1.30 / aq-mode=1 / aq-strength=1.00 / cutree / zone-count=0 / no-strict-cbr / qg-size=32 / no-rc-grain / qpmax=69 / qpmin=0 / no-const-vbv / sar=1 / overscan=0 / videoformat=5 / range=0 / colorprim=9 / transfer=16 / colormatrix=9 / chromaloc=0 / display-window=0 / master-display=G(13250,34500)B(7500,3000)R(34000,16000)WP(15635,16450)L(10000000,50) / max-cll=0,0 / min-luma=0 / max-luma=1023 / log2-max-poc-lsb=8 / vui-timing-info / vui-hrd-info / slices=1 / no-opt-qp-pps / no-opt-ref-list-length-pps / no-multi-pass-opt-rps / scenecut-bias=0.05 / no-opt-cu-delta-qp / no-aq-motion / hdr / no-hdr-opt / no-dhdr10-opt / no-idr-recovery-sei / analysis-reuse-level=5 / scale-factor=0 / refine-intra=0 / refine-inter=0 / refine-mv=0 / no-limit-sao / ctu-info=0 / no-lowpass-dct / refine-mv-type=0 / copy-pic=1 / max-ausize-factor=1.0 / no-dynamic-refine / no-single-sei
Default                                  : Yes
Forced                                   : No
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: 0.0040 cd/m2, max: 1100 cd/m2

I suspect Color range, Color primaries and Transfer characteristics are necessary to make the file recognized as HDR by my TV. How can I add these properties to the VAAPI encoded file?

Edit: This patch fixes the problem: Patch

Answer 1

Color range, Color primaries and Transfer characteristics are necessary to make the file recognized as HDR by my TV

No, only Transfer of PQ. File can be 8 bit, or use BT.709 primaries it will still trigger HDR.

How can I add these properties to the VAAPI encoded file?

Before that patch you needed to tag the file with -color_trc smpte2084 -color_primaries bt2020 -colorspace bt2020nc (first is transfer, a.k.a. tone response curve, second is primaries of linear RGB and third is matrix used for YCbCr encoding).