Tune encoder for encode dynamic video scenes with cbr option enabled

[alexcon314]

Hi.
I am developing a general purpose video encoding application. Encoder used with CBR (constant bit rate) option. It’
s important.

But artifacts appear on dynamic video scenes after encoding.
I provide screenshots of the video after encoding that I receive after running the example and the original video.

I followed these steps

# take h264 bitstream from mp4 container
ffmpeg -i design.mp4 -vcodec copy -an -bsf:v h264_mp4toannexb design.h264

# take decoded raw file
tegra_multimedia_api/samples/00_video_decode/video_decode H264 --disable-rendering -o design.raw design.h264

# encode raw file
tegra_multimedia_api/samples/01_video_encode/video_encode design.raw 3840 2160 H264 design_new.h264 -rc cbr --max-perf

What other options can you customize? What can you advise for setting up the encoder to encode such dynamic scenes.

My release version

# R32 (release), REVISION: 2.3, GCID: 17644089, BOARD: t186ref, EABI: aarch64, DATE: Tue Nov 5 21:48:17 UTC 2019

I am also attaching the original video file.

design_.zip (1.2 MB)

[DaneLLL]

Hi,
Be default the bitrate is 4Mbps which looks too small for 4K

        -br <bitrate>         Bitrate [Default = 4000000]

Suggest you try 16Mbps.

[alexcon314]

I am attaching result with original bitrate 23000K

# encode raw file with original bitrate
tegra_multimedia_api/samples/01_video_encode/video_encode design.raw 3840 2160 H264 design_new.h264 -rc cbr --max-perf -br 23000000

[DaneLLL]

Hi,
Please try to configure virtual buffer size:

        -vbs <size>           Virtual buffer size [Default = 0]

Here is a reference link:

H264 vs H265

Hi, For comparing h264 and h265, please use same YUV source and compare PSNR. For example, you may download the source: https://media.xiph.org/video/derf/y4m/park_joy_1080p50.y4m Run $ gst-launch-1.0 filesrc location= park_joy_1080p50.y4m ! y4mdec ! nvvidconv ! nvv4l2h264enc bitrate=14000000 control-rate=1 vbv-size=450000 ! h264parse ! qtmux ! filesink location= park_joy.mov $ gst-launch-1.0 filesrc location= park_joy_1080p50.y4m ! y4mdec ! nvvidconv ! nvv4l2h265enc bitrate=14000000 control…

And hardware preset type:

        -hpt <type>           HW preset type (1 = ultrafast, 2 = fast, 3 = medium,  4 = slow)

Please note hardware preset type improves image quality but affects encoding speed. Slow type may not be able to achieve 4Kp30.

[alexcon314]

unfortunately i got same result (artifacts) with following options

tegra_multimedia_api/samples/01_video_encode/video_encode design.raw 3840 2160 H264 design_new.h264 -rc cbr --max-perf -br 23000000 -vbs 56000000 -hpt 3

[DaneLLL]

Hi,
The setting looks strange. Bitrate is 23Mbps and virtual buffer size is 56Mbps. You may try virtual buffer size = bitrate/framerate. And 23Mbps may be small for 4K. Please try 40Mbps.

[alexcon314]

Ok.

Please show a set of parameters acceptable from your point of view for encoding this example video.

[DaneLLL]

Hi,
The scene looks complex and I think 40Mbps may not be enough. However, there is trade-off between video quality and bitrate. In general, 40Mbps should be good for most ordinary scenes.