ffmpeg hardware encoding H264

[marcorocchini]

Hi cats

I try to understand if there is a way to do an h264 hardware encoding with my notebook HP i7 J113EL

that have a Intel HD4600 + NVidia GT750M graphic cards

If I don't mistake using ffmpeg with -vcodec h264_nvenc is used the GT750M

but maybe it's usable also the quicksync function? or other hardware encoding method?

and if I use the NVidia encoding can I set to use -crf XY to do a Costant Rate Factor encoding?

thanks

[poisondeathray]

It' s in the help
ffmpeg -h full 1>ffmpeg_fullhelp.txt
quicksync
-c:v h264_qsv

nvenc doesn't have eqivalent "crf", but has cqp mode. For nvenc rate control options

  -rc                <int>        E..V.... Override the preset rate-control (from -1 to INT_MAX) (default -1)
     constqp                      E..V.... Constant QP mode
     vbr                          E..V.... Variable bitrate mode
     cbr                          E..V.... Constant bitrate mode
     vbr_minqp                    E..V.... Variable bitrate mode with MinQP (deprecated)
     ll_2pass_quality              E..V.... Multi-pass optimized for image quality (deprecated)
     ll_2pass_size                E..V.... Multi-pass optimized for constant frame size (deprecated)
     vbr_2pass                    E..V.... Multi-pass variable bitrate mode (deprecated)
     cbr_ld_hq                    E..V.... Constant bitrate low delay high quality mode
     cbr_hq                       E..V.... Constant bitrate high quality mode
     vbr_hq                       E..V.... Variable bitrate high quality mode

[marcorocchini]

mmm

I have try

ffmpeg.exe -threads 12 -y -i c0113.mxf -vf scale=interl=1 -c:v h264_qsv -profile:v high -g 33 -bf 2 -an -aspect 16:9 out.mp4

but strangely ffmpeg freeze and don't continue

C0113.mxf is a 4:2:2 video clip

[poisondeathray]

Try convert it to 420 , qsv doesn't support 422 encoding . If that doesn't work, try update driver

[marcorocchini]

and alternalitevly using the nvenc what parameter is more close to the CRF 22?
"-rc constqp" but in what way the quality value?

[poisondeathray]

"crf 22" is from a different encoder , different quality, different method of rate control. There won't be anything completely comparable

You have try some values and check if you like it

[marcorocchini]

ok but it there a practical example of use of - for example - the -rc constqp?

[pandy]

ok but it there a practical example of use of - for example - the -rc constqp?

fast encoding where output is pure VBR.

[raffriff42]

I could not get it to work until I found this thread

-c:v h264_nvenc -rc:v constqp -global_quality 20

Option "-q" etc does not work, defaults to very low quality.

[marcorocchini]

exactlly I don't why but yesteday the -c:v h264_nvenc works, and today I get this error


[Attachment 42287 - Click to enlarge]

using:

ffmpeg.exe -y -i c0113.mxf -vf scale=interl=1 -c:v h264_nvenc out.mp4

[sneaker]

Copy&paste the complete ffmpeg log. Is the source not 4:2:0 while ffmpeg's Nvidia encoder only supports 4:2:0 or something like that?

[raffriff42]

You have a notebook, don't you - and doesn't the nVidia notebook GPU shut down (reverting to CPU graphics) sometimes to save power? If so, you might want to force the GPU to stay active when connected to AC power, using power profiles.

[marcorocchini]

Copy&paste the complete ffmpeg log. Is the source not 4:2:0 while ffmpeg's Nvidia encoder only supports 4:2:0 or something like that?

ffmpeg version N-81646-gc19da0c Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
libavutil 55. 29.100 / 55. 29.100
libavcodec 57. 55.101 / 57. 55.101
libavformat 57. 48.103 / 57. 48.103
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 62.100 / 6. 62.100
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100
Guessed Channel Layout for Input Stream #0.1 : mono
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Guessed Channel Layout for Input Stream #0.4 : mono
Guessed Channel Layout for Input Stream #0.5 : mono
Guessed Channel Layout for Input Stream #0.6 : mono
Guessed Channel Layout for Input Stream #0.7 : mono
Guessed Channel Layout for Input Stream #0.8 : mono
Input #0, mxf, from 'c0113.mxf':
Metadata:
uid : d9611000-5277-05c1-0270-08004602023b
generation_uid : d9611000-5277-05c2-0270-08004602023b
company_name : SONY
product_name : Opt
product_version : 1.22
product_uid : 060e2b34-0401-0103-0e06-012002010300
modification_date: 2016-12-30T11:55:30.000000Z
material_package_umid: 0x060A2B340101010501010D4313000000549A160016780580 08004602023B0270
timecode : 00:29:35:14
Duration: 00:00:12.72, start: 0.000000, bitrate: 60347 kb/s
Stream #0:0: Video: mpeg2video (4:2:2), yuv422p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:1: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:2: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:3: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:4: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:5: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:6: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:7: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:8: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
[h264_nvenc @ 0000000002368b80] No NVENC capable devices found
Output #0, mp4, to 'out.mp4':
Metadata:
uid : d9611000-5277-05c1-0270-08004602023b
generation_uid : d9611000-5277-05c2-0270-08004602023b
company_name : SONY
product_name : Opt
product_version : 1.22
product_uid : 060e2b34-0401-0103-0e06-012002010300
modification_date: 2016-12-30T11:55:30.000000Z
material_package_umid: 0x060A2B340101010501010D4313000000549A160016780580 08004602023B0270
timecode : 00:29:35:14
Stream #0:0: Unknown: none, SAR 1:1 DAR 0:0
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
encoder : Lavc57.55.101 h264_nvenc
Stream #0:1: Unknown: none
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
encoder : Lavc57.55.101 aac
Stream mapping:
Stream #0:0 -> #0:0 (mpeg2video (native) -> h264 (h264_nvenc))
Stream #0:1 -> #0:1 (pcm_s24le (native) -> aac (native))
Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

[marcorocchini]

You have a notebook, don't you - and doesn't the nVidia notebook GPU shut down (reverting to CPU graphics) sometimes to save power? If so, you might want to force the GPU to stay active when connected to AC power, using power profiles.

I dont' know but not sure is a problem of the power profile however I keep alwais the maximum power in the pc using

powercfg.exe /setactive 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c

[marcorocchini]

Is the source not 4:2:0 while ffmpeg's Nvidia encoder only supports 4:2:0 or something like that?

oh I think you are right cat

[marcorocchini]

Please consider this 422 source:

https://www.dropbox.com/s/829iziwuetpdqm4/source422.MXF?dl=0

I have try to encode with libx264 using:

ffmpeg64bitmar2017.exe -threads 12 -y -i source422.MXF -pix_fmt yuv420p -vf scale=interl=1,format=pix_fmts=yuv420p -c:v libx264 -profile:v high -level:v 4.1 -g 33 -bf 2 -crf 21.6 -flags +ildct+ilme -top 1 -aspect 16:9 -an x264_420.MP4

and with NVENC using:

v:\automazioneclip\core\ffmpeg64bitmar2017.exe -threads 12 -y -i source422.mxf -pix_fmt yuv420p -vf scale=interl=1,format=pix_fmts=yuv420p -c:v h264_nvenc -rc:v constqp -global_quality 26 -level:v 4.1 -flags +ildct+ilme -top 1 -aspect 16:9 -an outNVENC.MP4

Here I have attach x264_420.MP4 and outNVENC.MP4

the x264 have more quality : the nvenc have a little "croma ghost" or an out of color in details... it's not the same quality of the x264.

Is there a way to have or to seems the "same" quality?

[poisondeathray]

The chroma notching errors look like not sending NV12 (NVEnc expects "NV12" , not yuv420p ) .

It is encoded with I-frame only . Try a slower preset -preset slow , which is an internal 2pass HQ mode for NVEnc, and includes bframes (unless constqp overrrides it, not sure)

[poisondeathray]

[h264_nvenc @ 0000000001cf7360] Using global_quality with nvenc is deprecated. Use qp instead.

-qp or -global_quality seem to override control and place I-frame only . Adding -bf 2 or some number doesn't overrride.

So I recommend using VBR RC instead with -preset slow, that's NVEnc's best mode . You're not going to get something analogous to "CRF"

[marcorocchini]

mmmm

v:\automazioneclip\core\ffmpeg64bitmar2017.exe -threads 12 -y -i source422.mxf -pix_fmt yuv420p -vf scale=interl=1,format=pix_fmts=yuv420p -c:v h264_nvenc -rc vbr_2pass -cq 30 -qmin 28 -qmax 30 -preset slow -bf 0 -global_quality 26 -level:v 4.1 -flags +ildct+ilme -top 1 -aspect 16:9 -an outNVENC.MP4

in this moment I cannot verify at CRT monitor the output however -BF 2 causes a wrong green color for 1/2 seconds at the beginning of the output, I'm forced to set to 0.

In the meantime I have try also the QSV encoder that seems resolve the problem of the "out of color"

ffmpeg64bitsett2016.exe -threads 12 -y -i c0113.mxf -filter_complex "[0:1] [0:2] amerge" -pix_fmt yuv420p -vf scale=interl=1,format=pix_fmts=yuv420p -c:v h264_qsv -global_quality 27 -level:v 4.1 -flags +ildct+ilme -top 1 -c:a ac3 -b:a 320k -ar 48000 -aspect 16:9 out56.MP4

but randomly I get this error


[Attachment 42308 - Click to enlarge]

ffmpeg version N-81646-gc19da0c Copyright (c) 2000-2016 the FFmpeg developers
built with gcc 5.4.0 (GCC)
configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-dxva2 --enable-libmfx --enable-nvenc --enable-avisynth --enable-bzlib --enable-libebur128 --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenh264 --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma --enable-decklink --enable-zlib
libavutil 55. 29.100 / 55. 29.100
libavcodec 57. 55.101 / 57. 55.101
libavformat 57. 48.103 / 57. 48.103
libavdevice 57. 0.102 / 57. 0.102
libavfilter 6. 62.100 / 6. 62.100
libswscale 4. 1.100 / 4. 1.100
libswresample 2. 1.100 / 2. 1.100
libpostproc 54. 0.100 / 54. 0.100
Guessed Channel Layout for Input Stream #0.1 : mono
Guessed Channel Layout for Input Stream #0.2 : mono
Guessed Channel Layout for Input Stream #0.3 : mono
Guessed Channel Layout for Input Stream #0.4 : mono
Guessed Channel Layout for Input Stream #0.5 : mono
Guessed Channel Layout for Input Stream #0.6 : mono
Guessed Channel Layout for Input Stream #0.7 : mono
Guessed Channel Layout for Input Stream #0.8 : mono
Input #0, mxf, from 'c0113.mxf':
Metadata:
uid : d9611000-5277-05c1-0270-08004602023b
generation_uid : d9611000-5277-05c2-0270-08004602023b
company_name : SONY
product_name : Opt
product_version : 1.22
product_uid : 060e2b34-0401-0103-0e06-012002010300
modification_date: 2016-12-30T11:55:30.000000Z
material_package_umid: 0x060A2B340101010501010D4313000000549A160016780580 08004602023B0270
timecode : 00:29:35:14
Duration: 00:00:12.72, start: 0.000000, bitrate: 60347 kb/s
Stream #0:0: Video: mpeg2video (4:2:2), yuv422p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:1: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:2: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:3: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:4: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:5: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:6: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:7: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
Stream #0:8: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
[Parsed_amerge_0 @ 00000000022c5480] No channel layout for input 1
[Parsed_amerge_0 @ 00000000022c5480] Input channel layouts overlap: output layout will be determined by the number of distinct input channels
Incompatible pixel format 'yuv420p' for codec 'h264_qsv', auto-selecting format 'nv12'
[mp4 @ 00000000022e3b00] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
Last message repeated 1 times
Output #0, mp4, to 'out56.MP4':
Metadata:
uid : d9611000-5277-05c1-0270-08004602023b
generation_uid : d9611000-5277-05c2-0270-08004602023b
company_name : SONY
product_name : Opt
product_version : 1.22
product_uid : 060e2b34-0401-0103-0e06-012002010300
modification_date: 2016-12-30T11:55:30.000000Z
material_package_umid: 0x060A2B340101010501010D4313000000549A160016780580 08004602023B0270
timecode : 00:29:35:14
encoder : Lavf57.48.103
Stream #0:0: Audio: ac3 ([165][0][0][0] / 0x00A5), 48000 Hz, stereo, fltp, 320 kb/s (default)
Metadata:
encoder : Lavc57.55.101 ac3
Stream #0:1: Video: h264 (h264_qsv) ([33][0][0][0] / 0x0021), nv12, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 1000 kb/s, 0.04 fps, 12800 tbn, 25 tbc
Metadata:
file_package_umid: 0x060A2B340101010501010D431301D8874960100052770580 08004602023B0270
encoder : Lavc57.55.101 h264_qsv
Side data:
cpb: bitrate max/min/avg: 0/0/1000000 buffer size: 0 vbv_delay: -1
Stream mapping:
Stream #0:1 (pcm_s24le) -> amerge:in0 (graph 0)
Stream #0:2 (pcm_s24le) -> amerge:in1 (graph 0)
amerge (graph 0) -> Stream #0:0 (ac3)
Stream #0:0 -> #0:1 (mpeg2video (native) -> h264 (h264_qsv))
Press [q] to stop, [?] for help
[h264_qsv @ 00000000025a3560] EncodeFrameAsync returned -17
Video encoding failed
Conversion failed!

[poisondeathray]

This is wrong for ffmpeg NVEnc

-pix_fmt yuv420p -vf scale=interl=1,format=pix_fmts=yuv420p

This is right for ffmpeg NVEnc (NV12)

-vf scale=interl=1,format=pix_fmts=nv12

Did you try update intel driver for QSV ? Are you using other application that is accessing QSV at same time ?

Have you ever been able to successfully encode using ffmepg QSV ? Did you try rigaya's QSVENCC? If you can encode with that you know it's not a hardware/driver issue

[poisondeathray]

Do you see difference?

Here is 1:1 cropped

Left is yuv420p , right is nv12

[gregalan]

ffmpeg -h encoder=h264_nvenc
ffmpeg version 3.3.2 Copyright (c) 2000-2017 the FFmpeg developers
built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.4) 20160609

libavutil 55. 58.100 / 55. 58.100
libavcodec 57. 89.100 / 57. 89.100
libavformat 57. 71.100 / 57. 71.100
libavdevice 57. 6.100 / 57. 6.100
libavfilter 6. 82.100 / 6. 82.100
libswscale 4. 6.100 / 4. 6.100
libswresample 2. 7.100 / 2. 7.100
libpostproc 54. 5.100 / 54. 5.100
Encoder h264_nvenc [NVIDIA NVENC H.264 encoder]:
General capabilities: delay
Threading capabilities: none
Supported pixel formats: yuv420p nv12 p010le yuv444p yuv444p16le bgr0 rgb0 cuda
h264_nvenc AVOptions:
-preset <int> E..V.... Set the encoding preset (from 0 to 11) (default medium)
default E..V....
slow E..V.... hq 2 passes
medium E..V.... hq 1 pass
fast E..V.... hp 1 pass
hp E..V....
hq E..V....
bd E..V....
ll E..V.... low latency
llhq E..V.... low latency hq
llhp E..V.... low latency hp
lossless E..V....
losslesshp E..V....
-profile <int> E..V.... Set the encoding profile (from 0 to 3) (default main)
baseline E..V....
main E..V....
high E..V....
high444p E..V....
-level <int> E..V.... Set the encoding level restriction (from 0 to 51) (default auto)
auto E..V....
1 E..V....
1.0 E..V....
1b E..V....
1.0b E..V....
1.1 E..V....
1.2 E..V....
1.3 E..V....
2 E..V....
2.0 E..V....
2.1 E..V....
2.2 E..V....
3 E..V....
3.0 E..V....
3.1 E..V....
3.2 E..V....
4 E..V....
4.0 E..V....
4.1 E..V....
4.2 E..V....
5 E..V....
5.0 E..V....
5.1 E..V....
-rc <int> E..V.... Override the preset rate-control (from -1 to INT_MAX) (default -1)
constqp E..V.... Constant QP mode
vbr E..V.... Variable bitrate mode
cbr E..V.... Constant bitrate mode
vbr_minqp E..V.... Variable bitrate mode with MinQP
ll_2pass_quality E..V.... Multi-pass optimized for image quality (only for low-latency presets)
ll_2pass_size E..V.... Multi-pass optimized for constant frame size (only for low-latency presets)
vbr_2pass E..V.... Multi-pass variable bitrate mode
-rc-lookahead <int> E..V.... Number of frames to look ahead for rate-control (from -1 to INT_MAX) (default -1)
-surfaces <int> E..V.... Number of concurrent surfaces (from 0 to 64) (default 32)
-cbr <boolean> E..V.... Use cbr encoding mode (default false)
-2pass <boolean> E..V.... Use 2pass encoding mode (default auto)
-gpu <int> E..V.... Selects which NVENC capable GPU to use. First GPU is 0, second is 1, and so on. (from -2 to INT_MAX) (default any)
any E..V.... Pick the first device available
list E..V.... List the available devices
-delay <int> E..V.... Delay frame output by the given amount of frames (from 0 to INT_MAX) (default INT_MAX)
-no-scenecut <boolean> E..V.... When lookahead is enabled, set this to 1 to disable adaptive I-frame insertion at scene cuts (default false)
-forced-idr <boolean> E..V.... If forcing keyframes, force them as IDR frames. (default false)
-b_adapt <boolean> E..V.... When lookahead is enabled, set this to 0 to disable adaptive B-frame decision (default true)
-spatial-aq <boolean> E..V.... set to 1 to enable Spatial AQ (default false)
-temporal-aq <boolean> E..V.... set to 1 to enable Temporal AQ (default false)
-zerolatency <boolean> E..V.... Set 1 to indicate zero latency operation (no reordering delay) (default false)
-nonref_p <boolean> E..V.... Set this to 1 to enable automatic insertion of non-reference P-frames (default false)
-strict_gop <boolean> E..V.... Set 1 to minimize GOP-to-GOP rate fluctuations (default false)
-aq-strength <int> E..V.... When Spatial AQ is enabled, this field is used to specify AQ strength. AQ strength scale is from 1 (low) - 15 (aggressive) (from 1 to 15) (default 8)
-cq <int> E..V.... Set target quality level (0 to 51, 0 means automatic) for constant quality mode in VBR rate control (from 0 to 51) (default 0)
-aud <boolean> E..V.... Use access unit delimiters (default false)
-bluray-compat <boolean> E..V.... Bluray compatibility workarounds (default false)
-init_qpP <int> E..V.... Initial QP value for P frame (from -1 to 51) (default -1)
-init_qpB <int> E..V.... Initial QP value for B frame (from -1 to 51) (default -1)
-init_qpI <int> E..V.... Initial QP value for I frame (from -1 to 51) (default -1)
-qp <int> E..V.... Constant quantization parameter rate control method (from -1 to 51) (default -1)


As you can see there is the "-cq" command to set target quality.

[poisondeathray]

As you can see there is the "-cq" command to set target quality.

I don't think it works, maybe not implemented properly yet. Or do you have to set some other settings as well ?

-cq 0 => 1.9Mb/s
-cq 18 => 1.9Mb/s
-cq 26 => 1.9Mb/s
-cq 40 => 1.6Mb/s

There is a change at 40 , but it's unwatchable at that bitrate

[gregalan]

I used

-c:v h264_nvenc -preset slow -cq 16 -rc-lookahead 16 -qmin 10 -qmax 23 -refs 4

and

-c:v h264_nvenc -preset slow -cq 20 -rc-lookahead 16 -qmin 10 -qmax 23 -refs 4

I got very different bitrates on a very small test video.

-cq 16 => 848.2kbits/s and q=9.0
-cq 20 => 592.8kbits/s and q=13.0

I might be wrong but I think -cq option only works with FFmpeg 3.3 or newer.

[poisondeathray]

Yes, that works - setting qmin, qmax is required

[marcorocchini]

Where source is this 422 video file:

https://www.dropbox.com/s/829iziwuetpdqm4/source422.MXF?dl=0

I get this x264.MP4 (attached) using:

ffmpeg64bitjuly2017.exe -threads 12 -y -i source422.mxf -pix_fmt yuv420p -vf scale=interl=1 -c:v libx264 -profile:v high -level:v 4.1 -g 33 -bf 2 -crf 22 -flags +ildct+ilme -top 1 -aspect 16:9 -an x264.MP4

quality is good: encoder is x264, file size 22 MB.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Try to encode using QSV (attached):

ffmpeg64bitjuly2017.exe -threads 12 -y -i source422.mxf -pix_fmt nv12 -vf scale=interl=1,format=pix_fmts=nv12 -c:v h264_qsv -global_quality 27.5 -level:v 4.1 -flags +ildct+ilme -top 1 -aspect 16:9 -an QSV.MP4

quality is good: encoder is Quick Sync, file size almost 22 MB

But: using the same untouched commandline sometimes work, sometimes freeze during encoding, sometimes return error (error during encoding: device failed (-17)) also changing the Intel HD4600 graphic drivers on my pc

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Try to encode using NVENC (attached):

ffmpeg64bitjuly2017.exe -threads 12 -y  -i source422.mxf -pix_fmt nv12 -vf scale=interl=1,format=pix_fmts=nv12 -c:v h264_nvenc -preset slow -cq 20 -qmin 10 -qmax 26 -refs 4 -profile:v high -level:v 4.1 -flags +ildct+ilme -top 1 -aspect 16:9 -an NVENC.MP4

file size is alwais 22MB. Quality is not bed but in the frame by frame comparison, seems that there is too many loss of details.

If I try to add -rc-lookahead 16 in the commandline I get [h264_nvenc @ 00000000023ac520] No NVENC capable devices found

However the problem is the loss of details

So is there a way to improove the quality of this NVENC encoding? thanks

[marcorocchini]

I try -cq at different value but does not change the final size: seems that the bitrate change changing the -qmax value

[marcorocchini]

And there is a strange things in the NVENC output:

General
Complete name : V:\C0122\NVENC.MP4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom
File size : 22.1 MiB
Duration : 14s 80ms
Overall bit rate mode : Variable
Overall bit rate : 13.2 Mbps
Writing application : Lavf57.75.100

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Main@L4.1
Format settings, CABAC : Yes
Format settings, ReFrames : 4 frames
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 14s 80ms
Bit rate mode : Variable
Bit rate : 13.2 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate mode : Constant
Frame rate : 25.000 fps
Original frame rate : 50.000 fps
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Bits/(Pixel*Frame) : 0.254
Stream size : 22.1 MiB (100%)


Is there a way to don't see the Original Framerate = 50 ?

[poisondeathray]

Is there a way to don't see the Original Framerate = 50 ?

just don't look at it




I think that's what nvenc does with interlaced video. rigaya's nvencc does that too for the "original frame rate". Maybe you can patch it after

[gregalan]

-rc-lookahead 16[/B] in the commandline I get [h264_nvenc @ 00000000023ac520] No NVENC capable devices found

However the problem is the loss of details

So is there a way to improove the quality of this NVENC encoding? thanks

Your GT 750M is first gen nvenc so it may not support some options, also quality wasn't very good with Kepler GPUs.